ALBERT

Description: We explore a parameterization for mesoscale turbulence, closely related to that of Gent and McWilliams, in which forcing terms proportional to the isopycnal flux of potential vorticity appear in the averaged momentum equations. We show that in the presence of variable bottom topography, the parameterization predicts alongslope mean flow and a corresponding upslope bolus (eddy) flux of tracer that is associated with an alongslope-directed bottom eddy stress. The upslope bolus flux is in qualitative agreement with observations of a cold dome over seamounts. The predicted alongslope flow corresponds to flow fields found in geostrophic turbulence experiments and has some similarity (although conceptually very different, as discussed in the text) to Holloway's prediction based on statistical mechanics. By considering continuous stratification as a limiting case of a multilayer model, we show how to treat the surface and bottom boundaries. Practical application of the parameterization is illustrated using a three-dimensional -coordinate ocean circulation model that is very similar to the Bryan–Cox–Semtner model. The model-computed flow is consistent with observations of anticyclonic flow around a seamount. We show that the bottom eddy stress associated with the parameterization can be large, even compared to the annual mean surface wind stress, and hence could have important implications for the biology and water mass distribution of the coastal ocean as well as for the large-scale ocean circulation. From the climate modelling perspective, the approach adopted here provides a single formalism that combines the advantages of the Gent and McWilliams parameterization with alongslope mean flow similar to that suggested by Holloway.

Description: The process of fluid release from the subducting slab beneath the Izu arc volcanic front (Izu VF) was examined by measuring B concentrations and B isotope ratios in the Neogene fallout tephra (ODP Site 782A). Both were measured by secondary ion mass spectrometry, in a subset of matrix glasses and glassy plagioclase-hosted melt inclusions selected from material previously analyzed for major and trace elements (glasses) and radiogenic isotopes (Sr, Nd, Pb; bulk tephra). These tephra glasses have high B abundances (∼10–60 ppm) and heavy δ11B values (+4.5‰ to +12.0‰), extending the previously reported range for Izu VF rocks (δ11B, +7.0‰ to +7.3‰). The glasses show striking negative correlations of δ11B with large ion lithophile element (LILE)/Nb ratios. These correlations cannot be explained by mixing two separate slab fluids, originating from the subducting sediment and the subducting basaltic crust, respectively (model A). Two alternative models (models B and C) are proposed. Model B proposes that the inverse correlations are inherited from altered oceanic crust (AOC), which shows a systematic decrease of B and LILE with increasing depth (from basaltic layer 2A to layer 3), paralleled by an increase in δ11B (from ∼+1‰ to +10‰ to +24‰). In this model, the contribution of sedimentary B is insignificant (〈4% of B in the Izu VF rocks). Model C explains the correlation as a mixture of a low-δ11B (∼+1‰) ‘composite’ slab fluid (a mixture of metasediment- and metabasalt-derived fluids) with a metasomatized mantle wedge containing elevated B (∼1–2 ppm) and heavy δ11B (∼+14‰). The mantle wedge was likely metasomatized by 11B-rich fluids beneath the outer forearc, and subsequently down dragged to arc front depths by the descending slab. Pb–B isotope systematics indicate that, at arc front depths, ∼53% of the B in the Izu VF is derived from the wedge. This implies that the heavy δ11B values of Izu VF rocks are largely a result of fluid fractionation, and do not reflect variations in slab source provenance (i.e. subducting sediment vs. basaltic crust). Since the B content of the peridotite at the outer forearc (7–58 ppm B, mean 24±16 ppm) is much higher than beneath the arc front (∼1–2 ppm B), the hydrated mantle wedge must have released a B-rich fluid on its downward path. This ‘wedge flux’ can explain (1) the across-arc decrease in B and δ11B (e.g. Izu, Kuriles), without requiring a progressive decrease in fluid flux from the subducting slab, and (2) the thermal structure of volcanic arcs, as reflected in the B and δ11B variations of volcanic arc rocks.

Description: Fluorescence derivatization provides a means of tracing the dynamics of polysaccharides even in the presence of high concentrations of other organic compounds or salts. A method of labeling polysaccharides with fluoresceinamine was extended to polysaccharides of a wide range of chemical composition, and alternative means of preparation were established for polysaccharides not initially amenable to column chromatography. The polysaccharides were activated with cyanogen bromide, coupled to fluoresceinamine, and separated from unreacted fluorophore via gel filtration chromatography or dialysis. Since the resulting derivatized polysaccharides proved to be stable to further physical and chemical manipulation, methods were also developed for re-activation and labeling with a second fluorophore, as well as for tethering the labeled polysaccharides to agarose beads. As an example of the application of this approach, five distinct fluorescently-labeled polysaccharides (pullulan, laminarin, xylan, chondroitin sulfate, and alginic acid) were used to investigate the activities and structural specificities of extracellular enzymes produced in situ by marine microbial communities, providing a means of measuring specifically the activities of endo-acting extracellular enzymes and avoiding use of low molecular mass substrate proxies. These labeled polysaccharides could be used to explore the dynamics of polysaccharides in other types of complex media, as well as to investigate the activities and specificities of endo-acting enzymes in other systems.

Description: The Sarulla graben is a composite Plio-Pleistocene basin developed along the northwest striking, dextral-slip Sumatra fault in a region where the fault coincides with the Sumatra volcanic arc. Offset of the 0.27±0.03 Ma Tor Sibohi rhyodacite dome by an active strand of the Sumatra fault, the Tor Sibohi fault (TSF), indicates a slip rate of about 9 mm/y. This value is lower than previous regional estimates of ∼25–30 mm/y for Holocene slip on the Sumatra fault determined from stream offsets in the Taratung region. This discrepancy may be due to (1) a difference between Holocene and late Quaternary rates of slip and (2) additional slip on other faults in the Sarulla area. Since the magnitude of undated stream offsets along the TSF in the Sarulla area is similar to those in the Taratung area, the discrepancy is likely to be due largely to a change in slip rate over time. Within the Sarulla area, major volcanic centers include the Sibualbuali stratavolcano (∼0.7–0.3 Ma), the Hopong caldera (∼1.5 Ma), and the Namora-I-Langit dacitic dome field (0.8–0.1 Ma). These centers generated the majority of the ash-flow tuffs and tuffaceous sediments filling the Sarulla graben, and appear to have been localized by structural features related to the Sumatra fault zone. Four geothermal systems within the Sarulla area are closely linked to major faults and volcanic centers. In three of the systems, reservoir permeability is clearly dominated by specific structures within the Sumatra fault system. In the fourth geothermal system, Namora-I-Langit geothermal field, permeability may be locally influenced by faults, but highly permeable fractures are widely distributed.

Description: Siderophores are low molecular weight, iron-chelating ligands produced by nearly all microorganisms. Fungi synthesize a wide range of hydroxamate siderophores. This review considers the chemical and biological aspects of these siderophores, their distribution amongst fungal genera and their possible applications. Siderophores function primarily as iron transport compounds. Expression of siderophore biosynthesis and the uptake systems is regulated by internal iron concentrations. Transport of siderophores is an energy-dependent process and is stereoselective, depending on recognition of the metal ion coordination geometry. In addition to transporting iron, siderophores have other functions and effects, including enhancing pathogenicity, acting as intracellular iron storage compounds and suppressing growth of other microorganisms. Siderophores can complex other metals apart from iron, in particular the actinides. Because of their metal-binding ability there are potential applications for siderophores in medicine, reprocessing of nuclear fuel, remediation of metal-contaminated sites and the treatment of industrial waste.

Description: Three methods for calculating the parameters of the Weibull wind speed distribution for wind energy analysis are presented: the maximum likelihood method, the proposed modified maximum likelihood method, and the commonly used graphical method. The application of each method is demonstrated using a sample wind speed data set, and a comparison of the accuracy of each method is also performed. The maximum likelihood method is recommended for use with time series wind data, and the modified maximum likelihood method is recommended for use with wind data in frequency distribution format.

Description: The electric generating capacity of Turkey must be tripled by 2010 to meet Turkey’s electric power consumption, if the annual 8% growth in electric power consumption continues. Turkey has to make use of its renewable energy resources, such as wind and solar, not only to meet the increasing energy demand, but also for environmental reasons. Studies show that Iskenderun (36°35′N; 36°10′E) located on the Mediterranean coast of Turkey is amongst the possible wind energy generation regions. In the present study, the wind energy potential of the region is statistically analyzed based on 1-year measured hourly time-series wind speed data. The probability density distributions are derived from time-series data and distributional parameters are identified. Two probability density functions are fitted to the measured probability distributions on a monthly basis. The wind energy potential of the location is studied based on the Weibull and the Rayleigh models.

Description: Using contemporary CO2 data from the subsurface Weddell Sea, the source/sink function of this region against the changing atmospheric CO2 level has been investigated. As in the central Weddell Sea, surface water is supplied by upwelling of subsurface water, the CO2 content is also forced by it. TCO2 data of four cruises were used to determine a robust value for the subsurface Warm Deep Water (WDW). After accounting for biological activity in the surface layer and salinity differences between the subsurface and surface waters, the forcing CO2 partial pressure (pCO2) was calculated from the TCO2 of the WDW and the conservative alkalinity as taken from the literature. As the WDW contains negligible anthropogenic CO2, the pCO2 forcing by the WDW has been prevalent both in the pre-industrial and modern Weddell Sea. The calculated pCO2 forcing amounts to 300–310 μatm at a minimum in late winter/early spring and possibly 30 μatm more during spring and summer. This figure does not represent the actual pCO2, but rather the value before air–sea exchange gets effective. Hence, in pre-industrial times when the atmospheric pCO2 was about 280 μatm, the Weddell Sea must have been a relatively strong source of atmospheric CO2. Because of the steadily rising atmospheric CO2 levels to more than the pCO2 forcing by the WDW, the Weddell Sea turned into a CO2 sink in recent times. The storage of anthropogenic CO2 in the Weddell Sea surface layer is estimated to be 4.1 mol C m−2. Applying the WDW forcing method to O2, a steady state O2 uptake from the atmosphere of 3.6 mol O2 m−2 year−1 is computed.

Description: We provide an overview of the basic concepts of scaling and dimensional analysis, followed by a review of some of the recent work on applying these concepts to modeling instrumented indentation measurements. Specifically, we examine conical and pyramidal indentation in elastic–plastic solids with power-law work-hardening, in power-law creep solids, and in linear viscoelastic materials. We show that the scaling approach to indentation modeling provides new insights into several basic questions in instrumented indentation, including, what information is contained in the indentation load–displacement curves? How does hardness depend on the mechanical properties and indenter geometry? What are the factors determining piling-up and sinking-in of surface profiles around indents? Can stress–strain relationships be obtained from indentation load–displacement curves? How to measure time dependent mechanical properties from indentation? How to detect or confirm indentation size effects? The scaling approach also helps organize knowledge and provides a framework for bridging micro- and macro-scales. We hope that this review will accomplish two purposes: (1) introducing the basic concepts of scaling and dimensional analysis to materials scientists and engineers, and (2) providing a better understanding of instrumented indentation measurements.

Description: Egg production, egg viability and fecal pellet production were determined for individual Acartia omorii, which were fed diets of two species of diatoms (Skeletonema costatum and Phaeodactylum tricornutum) and three species of dinoflagellates (Scrippsiella trochoidea, Heterocapsa triquetra and Cochlodinium polykrikoides). Diets were analyzed for fatty acid content as an indicator of food quality. Depending on the diet, egg production of A. omorii varied over time, diminishing with some diets (S. trochoidea, C. polykrikoides, P. tricornutum). This rate of reduction was much more rapid for a diet of C. polykrikoides, which caused egg production to decrease to ca. 2.4 eggs f−1 d−1 in only four days. As for all diets, egg viability was high at the beginning but with the C. polykrikoides and P. tricornutum diets, it rapidly decreased with time. Fecal pellet production also varied with time, depending on the diet. Egg production rate was closely correlated with fecal pellet production. There was no direct relationship between egg viability and egg production rate, but both egg production and viability were affected by the nutritional quality of food. Egg viability was also highly dependent on the composition of fatty acids in the eggs. Egg viability showed positive correlation with the ratio of ω3:ω6 groups among egg fatty acids, and negative correlation with the ratio of 20:5 (n−3) : 22:6 (n−3). While comparing several diets, egg production rate was higher on diets (H. triquetra and S. trochoidea) containing ample amounts of essential fatty acids such as 18:4 (n−3) and 22:6 (n−3). The results suggest that fertility of A. omorii was dependent upon the quality of the food, and dinoflagellate diets, with the exception of C. polykrikoides, were preferable to diatom diets.

Description: Recently, researchers have begun to identify the prevalence of trait simplification, loss and reversal across all levels of biological organization. These studies have taken increasingly integrated approaches, incorporating phylogenetic, developmental and molecular methods, in the quest towards understanding the patterns and processes behind evolution in reverse. Here, we highlight the emerging interest in the reversibility of evolution by discussing a spectrum of studies examining both the genotypes and phenotypes of evolution in reverse. These integrative approaches have greatly increased our knowledge of the biological interactions that produce patterns of evolution in reverse and have led to promising new areas of research.

Description: A search for antibacterial activity in different organs/tissues of the horse mussel, Modiolus modiolus, was conducted. Dried samples were extracted with 60% (v/v) acetonitrile, containing 0.1% (v/v) trifluoroacetic acid. Due to high salt content, two liquid phases were obtained; an acetonitrile-rich phase (ACN extract) and an aqueous phase. The aqueous phase was further subjected to solid phase extraction (SPE). Eluates from SPE and ACN extracts were tested for antibacterial, lysozyme, and toxic activity. Antibacterial activity was demonstrated in extracts from several tissues, including plasma, haemocytes, labial palps, byssus, mantle, and gills. Some of the extracts were sensitive to proteinase K treatment, indicating antibacterial peptides and/or proteins. Lysozyme-like activity and toxic activity against Artemia salina nauplii was detected in fractions from the gills, mantle, muscle, and haemocytes. Results from this study indicate that M. modiolus is a promising source for identifying novel drug lead compounds.

Description: Physical and chemical fluid–rock interactions are implicated in controlling earthquake nucleation and recurrence. In particular, interseismic compaction, sealing and healing of fractured fault rocks can lead to strength recovery and stabilisation of fault zones. In contrast, these same processes can also assist increases in pore fluid pressures and consequent destabilisation of faults. Here, we present high-temperature, hydrothermal experiments designed to assess the evolution of strength of fault zones in previously intact rock, and also characterise the associated changes to porosity and permeability. Cores of Fontainebleau sandstone were initially loaded to failure in a high-pressure gas–medium apparatus. The failed specimens were then hydrothermally reacted at 927°C for variable duration under isostatic conditions, and subsequently re-fractured to determine the ‘interseismic’ strength recovery. In the most extreme case, hydrothermally induced gouge compaction, cementation and crack healing resulted in 75% strength recovery after reaction for 6 h. Isostatic hydrothermal treatment also resulted in dramatic reduction in porosity and permeability. Strength of the fault zone following hydrothermal reaction appears to be closely correlated to porosity, consistent with previous studies on brittle failure of porous aggregates. The experimental results show how hydrothermal reactions in fault zones may lead to two competing, time-dependent effects; fault strengthening due to increased cohesion in the fault zone and fault weakening arising from elevated pore pressures within a well cemented, low-permeability gouge layer.

Description: We report results from time-series decay and sequential leaching experiments of laboratory cultured and coastal plankton to elucidate the mechanisms controlling barite formation in seawater. Batch-cultured diatoms (Stephanopyxis palmerina) and coccolithophorids (Emiliania huxleyi) were let to decay in the dark for 8–10 weeks, suspended in aerated seawater. The development of barite crystals was monitored by Scanning Electron Microscopy (SEM). A similar experiment was conducted with plankton collected during the spring-bloom in Vineyard Sound (MA). In addition to SEM, suspended particles were sequentially leached for Ba (distilled water rinse; 10% (v/v) HNO3 rinse at room temperature; 30% (v/v) HCl at 80°C overnight; 50% (v/v) HNO3 at 80°C overnight) immediately after collection, and after 10-week decay in seawater, in seawater poisoned with HgCl2, and in seawater spiked with 135Ba. Both experiments showed an increase in the number of barite crystals during decay. The spring-bloom plankton had initially a large pool of labile Ba, soluble in distilled water and cold dilute HNO3 that was lost from the plankton after 10-week decay in both axenic and nonaxenic conditions. In contrast, Ba in the decayed plankton samples was predominantly in forms extracted by hot HCl and hot HNO3 acids, which were attributed to presence of barite Ba and refractory organic Ba respectively. The increase in barite crystal counts under a Scanning Electron Microscope (SEM), the increase in HCl extractable Ba relative to organic carbon, and the loss of a large fraction of Ba during plankton decay suggest that living plankton consists of a relatively large pool of labile Ba, which is rapidly released during plankton decomposition and acts as the main source of Ba for barite formation in supersaturated microenvironments. Since mass balance indicates that only a small proportion (2 to 4%) of the labile-Ba pool is converted to barite, the availability of microenvironments that could locally concentrate Ba released by plankton decay seems to be the main limiting factor in barite precipitation.

Description: Eclogites from the Earth's mantle found in kimberlites provide important information on craton formation and ancient geodynamic processes because such eclogites are mostly Archean in age. They have equilibrated over a range of temperatures and pressures throughout the subcratonic mantle and some are diamond-bearing. Most mantle eclogites are bimineralic (omphacite and garnet) rarely with accessory rutiles. Contrary to their overall mineralogical simplicity, their broadly basaltic-picritic bulk compositions cover a large range and overlap with (but are not identical to) much younger lower grade eclogites from orogenic massifs. The majority of mantle eclogites have trace element geochemical features that require an origin from plagioclase-bearing protoliths and oxygen isotopic characteristics consistent with seawater alteration of oceanic crust. Therefore, most suites of eclogite xenoliths from kimberlites can be satisfactorily explained as samples of subducted oceanic crust. In contrast, eclogite xenoliths from Kuruman, South Africa and Koidu, Sierra Leone stem from protoliths that were picritic cumulates from intermediate pressures (1–2 Ga) and were subsequently transposed to higher pressures within the subcratonic mantle, consistent with craton growth via island arc collisions. None of the eclogite suites can be satisfactorily explained by an origin as high pressure cumulates from primary melts from garnet peridotite.

Description: Three tephra layers have been identified in the upper 15 m of a 190-m section of peat beneath the Philippi fen. They provide significant lithological and chronological markers throughout the fen and the Aegean region. The upper tephra (PhT1) consists of shards of a transparent calcalkaline felsic glass and fragments of plagioclase, augite, hypersthene, and rare hornblende, magnetite, apatite and quartz. Peat directly beneath PhT1 gave a radiocarbon approximate age of 13,000 yr. The middle tephra layer (PhT2), which resembles PhT1 in chemistry and petrography but contains more crystals and lithic fragments, rests on peat dated ca 18,000 14C yr BP. The lower tephra (PhT3) has colorless to brown glass shards with a trachytic chemistry and a mineral assemblage of sanidine, sodic plagioclase, biotite, aegirine-augite, hornblende, titanite and apatite. Bracketing radiocarbon ages imply that PhT3 accumulated about ∼30,000 14C yr BP. The likely ages of PhT1 and PhT2, together with their mineralogical and chemical characteristics, suggest that these tephras came from the volcanic field of Thera in the Hellenic arc. PhT2 particularly was derived from a major, known explosive eruption ca 18,000 yr BP, the Cape Riva eruption, correlative to the Y-2 tephra layer. Evidence for PhT3 suggests derivation from the Campanian Province of Italy, and correlation with the Campanian Ignimbrite and the Y-5 ash beneath the Mediterranean Sea.

Description: The purpose of this study was to establish a bioassay from isolated digestive gland cells of the cuttlefish Sepia officinalis in order to observe the effect of heavy metals on digestive enzyme activities. Digestive cells were isolated using a pronase enzyme that was removed by several washings of the cell suspension. Cell viability was tested by the MTT assay (3-4,5-dimethylthiazol-2-yl-2,5-diphenyl tetrazolium) and microscopic analysis. The results showed that isolated digestive cells could be maintained 24 h with preservation of whole digestive functionality, measured in terms of MTT test. In fact, the viability was maintained at a high level during 24 h and the intra- and extracellular digestive enzyme activities became stabilised rapidly. Furthermore, suspension cells responded to calcium ionophore and 8-Bromo-cAMP by an unspecific secretion of extracellular digestive enzyme, trypsin, which demonstrated that isolated digestive cells were functional. Using the bioassay, ecotoxicological studies showed that heavy metals could have effects on digestive enzyme activities after 24 h of an incubation time of the metal with the cells. In fact, zinc and silver affected trypsin and/or cathepsins specific activity of the cells. On the contrary, copper had no effect on digestive enzyme activities. Zinc, which is a trace element in all living animals, generated two different responses of cathepsins and cell viability. At a low concentration (0.02 μM), it increased viability and cathepsins specific activity, whereas at a high concentration (0.02 mM), zinc inhibited the cathepsins specific activity with an inhibition of cathepsins. For silver, whatever the tested concentration (0.02 mM or 0.02 μM), it has no impact on digestive gland isolated cell viability. Nevertheless, heavy metal induced high disturbance of enzymatic systems.

Description: Hatchlings cuttlefish were reared in the laboratory from hatching until 30 days old, fed with live shrimp, frozen shrimp or fish oil-enriched frozen shrimp. Survival of cuttlefish fed with oil-enriched frozen shrimp was better than in animals receiving live shrimp. However, there was no difference with cuttlefish fed with frozen shrimp, even if survival of those receiving oil-enriched frozen shrimp was always higher all along the experiment. Lower survival in animals fed with live shrimp represented the problem of using such food and confirms the necessity to elaborate an artificial food. Utilization of artemia was detrimental to growth and induced low values of instantaneous growth rate (IGR) and conversion rate even after feeding cuttlefish with shrimp. Nevertheless, growth parameters evolutions generally corresponded to those observed by other researchers. The profile noticed at the end of the experiment is typically observed when cuttlefish acquire their adult digestive system. Main differences were observed between groups fed with live shrimp or oil-enriched frozen shrimp. Enrichment did not induce same growth as in cuttlefish receiving live prey. However, at 20 and 25 days after hatching (DAH), in cuttlefish fed with oil-enriched frozen shrimp, ration was lower for the same growth than in other groups. These data showed capacity of juvenile cuttlefish to adjust their digestive enzyme activities according to the diet and the stage of development. Indeed, chymotrypsin was strongly influenced by enrichment, while other enzymes showed difference between live and frozen preys. Trypsin exhibited regulation by diet after 20 DAH. Freezing seemed to delay development as acid phosphatases, characteristic of first stages of cuttlefish, had lower activity in cuttlefish fed with live shrimp at 10 DAH. Moreover, influence of the stage of development was strong as activities between 20 and 30 DAH were different in all groups. This was in relation with evolution of the digestive system. These data illustrated the difficulty to elaborate optimal diet as digestive system evolves.

Description: Abundance of the loliginid squid Loligo forbesi in Western and Northern Scottish (UK) waters (ICES fishery subdivisions IVa and VIa) 1989–1998 was estimated using “depletion” methods. Fishery catch and effort data for UK and French fishing vessels were obtained from official government statistics. Biological data were collected during monthly sampling visits to Kinlochbervie (Scotland, UK) fish market. Effects of using different indices for natural mortality and different model fits were evaluated. The results indicate initial (pre-fishing season) annual population sizes in the order of 106 animals. Significant between-year variation in the seasonal pattern of body weight and recruitment indicates that contemporaneous biological data, collected every month (or more frequently) are needed to underpin annual estimates.

Description: The deep pelagic habitat is a vast volume of cold, dark water where food is scarce and bioluminescence is the principal source of light and communication. Understanding the adaptations that allow animals to successfully inhabit this daunting realm has been a difficult challenge because investigators have had to conduct their work remotely. Research in the deep water column is going through an essential transformation from indirect to direct methods as undersea vehicles provide unprecedented access, new capabilities, and new perspectives. Traditional methods have accurately documented the meso- and macro-scale zoogeographic patterns of micronekton and zooplankton, as well as their distribution and migration patterns in the vertical plane. The new in situ technologies have enabled advances in studies of behavior, physiology, and in particular, the role of gelatinous animals in deep pelagic ecology. These discoveries reveal a deep-water fauna that is complex and diverse and still very poorly known.

Description: The ‘ctenoglossans’ are an enigmatic group of transparent, pelagic octopuses that spend their entire life without touching the seafloor. Molecular and morphological evidence shows that the ctenoglossans have arisen via neoteny, the persistence of larval attributes in the adult form. The ctenoglossans have evolved from the planktonic early-dispersal stages of familiar benthic octopuses. Extreme adaptations of this group to their midwater habitat have masked their origins. The general appearance of the ctenoglossans is strikingly similar to that of non-octopod midwater cephalopods, the Glass Squids (family Cranchiidae). The Ctenoglossa include three families: the Glass Octopus (Family Vitreledonellidae, Figure 1A), Telescope Octopus (Family Amphitretidae, Figure 1B), and members of the family Bolitaenidae (Figures 1C,D). These octopuses live in tropical and temperate waters worldwide and possess many adaptations to their pelagic lifestyle, such as a transparent body, reduced organ size, modified eyes and in certain taxa large, simple chromatophores and light-producing organs. These adaptations have complicated morphological analyses and obscured the phylogenetic relationships of this group within the Octopoda 1., 2.. Naef proposed that the Ctenoglossa diverged from all other octopods in the Upper Cretaceous [1]. Voight proposed that the Ctenoglossa were polyphyletic, with the Bolitaenidae placed as the sister group to all remaining incirrate octopuses, while the Amphitretidae and Vitreledonellidae were grouped with the shelled argonauts and their relatives (superfamily Argonautoidea)

Description: The majority of squid families (Teuthoidea: Cephalopoda) exchange sodium for ammonium, creating a low-density fluid that imparts lift for neutral buoyancy. However, previous methods for measuring ammonium did not distinguish between NH4+ and various other amine compounds. The present study, using single column ion chromatography, reassessed the cation concentrations in several midwater cephalopod species. High NH4+ levels were confirmed for histioteuthid, cranchiid, and chiroteuthid and related squids. A strong relationship is reported between ammonium content and body mass in Histioteuthis heteropsis, suggesting a gradual accumulation of ammonium coincident with an ontogenetic migration to greater depths. The bathypelagic squids Bathyteuthis abyssicola and Bathyteuthis berryi, on the other hand, contained very little ammonium but rather contained large quantities of an as yet unidentified cation. The ecological significance of this compound is not yet known. Morphology in Bathyteuthid squids suggests that the unknown cation is contained intracellularly and so, unlike sequestered ammonia, does not diminish the space available for muscle tissue. Accordingly, protein measurements in B. berryi mantle muscle are on par with shallower-living muscular squids, and in situ submersible observations reveal strong locomotory abilities relative to other deep-water squids.

Description: During the present study, we aimed to provide a first look at the amino acid composition of the early stages of cephalopods and follow possible effects of certain dietary treatments. Amino acid profiles of cuttlefish Sepia officinalis, squid Loligo vulgaris and octopus, Octopus vulgaris hatchlings and wild juveniles of L. vulgaris and O. vulgaris were analysed. Cephalopod hatchlings showed high fractions of non-protein nitrogen (NPN), from 25% to 38% of the dry weight. Lysine, leucine and arginine represented half of the total content of essential amino acids (EAA), and glutamate and aspartate represented also nearly half of the non-essential amino acids (NEAA). In O. vulgaris, a general tendency for a decrease in the level of EAA from mature ovary and eggs to hatchlings was observed. Hatchlings after 4 days of fasting lost 28% of their dry weight and the level of EAA and NEAA decreased in both the total content and free forms. Free proline after 2 days of fasting and free tyrosine at 4 days of fasting were not detected. Comparison of the total EAA profiles of preys showed few differences between enriched Artemia nauplii and hatching crab zoeae (Pagurus prideaux and Maja squinado). The enriched Artemia nauplii EAA profiles showed no differences with the EAA profiles of O. vulgaris paralarvae during first 10 days of culture, except for histidine. Present results confirm the positive capacity for amino acid uptake from seawater by early stages of cephalopods. In the three species analysed, radiolabelled phenylalanine was incorporated in inverse relation to body size. After 10 days of culture, O. vulgaris paralarvae showed a tendency to increase the levels of total and free amino acids in the groups receiving a daily amino acids solution. At 20 days of age, the O. vulgaris cultures that received the amino acids solution had survivals that on average were three times that of the control group. However, the supposed beneficial effects of the amino acids solution remained unclear, as the dry weight of these paralarvae was equal or lower to that of paralarvae from the control group. In wild O. vulgaris juveniles, the percentage of protein and total amino acids increased with the dry weight of the individuals. These juvenile biochemical changes were associated with strong morphometric changes in body proportions after settlement with the development of the muscular, protein-rich arm crown.

Description: The potential for aquaculture of the cephalopod species Octopus vulgaris is evaluated, taking into consideration biological and physiological characteristics, as well as some economic and marketing aspects, which may be relevant for the future development of octopus farming. O. vulgaris, a widespread, strictly marine species meets many of the requirements to be considered as a candidate for industrial culture: easy adaptation to captivity conditions, high growth rate, acceptance of low-value natural foods, high reproductive rate and high market price. The life cycle from eclosion of eggs to settlement or beginning of the benthonic adult phase is not commercially viable, but the published results from laboratory and pilot scales are promising. Comments are also made on general research lines needed to improve the use of octopus as farmed species in the future.

Description: This paper presents data on the population structure, maturation patterns, fecundity, reproduction, and length–weight relationships of the European squid, Loligo vulgaris, in the Central Adriatic Sea. This species is one of the most valuable commercial cephalopods in the fishery of the Adriatic Sea, yet the population structure and reproductive biology are poorly known. The data are based on the analysis of 1583 individuals caught between 1998 and 2000 along the Croatian coast. In the major part of the year the sex ratio was close to 1:1, but in certain months males outnumbered females. Males were dominant in the smallest and the largest individuals, but at medium lengths females dominated. The length–weight relationship and dorsal mantle length at first sexual maturity for both sexes is given. Male and female reproductive outputs were counted and measured. Oocytes from the ovaries and oviducts of mature females were at various phases of development. Monthly changes of maturity indices, coefficients and frequency of appearance of advanced maturity stages showed a pattern of seasonal development with low values during summer and very high values during winter and spring. The spawning peaks were between January and May, but mature individuals were caught in all months, indicating that in the Central Adriatic Sea this species spawns throughout the year.

Description: Dissolved organic matter (DOM) is an important constituent of soil solution that plays a role in many chemical and biological processes in soils. Tremendous strides have been made in the past 25 years to more fully describe the composition of DOM and its role in soil. The papers in this special issue contribute to this literature by both summarizing recent research and reporting on new projects. Based on the papers presented here and others in the literature, I suggest that the following three questions would prove fruitful for future research on DOM in soils: (1) How large are various sources and sinks and how are they controlled?; (2) What is the ecological significance of dissolved organic nitrogen (DON) in comparison to dissolved organic carbon (DOC)?; (3) How are fluxes altered in human-dominated environments? In support of answering these questions, I recommend that emphasis be placed on developing new analytical techniques (isotopic, or detailed characterization of DOM constituents), increasing interchanges between aquatic and terrestrial biogeochemists and developing an integrated conceptual approach to the study of DOM in soils that addresses interactions among solid soil organic matter, microorganisms including fungi and mycorrhizal fungi, and DOM.

Description: In 1996, long-term sealed-hole hydrological observatories with subseafloor temperature and pressure sensors were installed in four cased holes drilled by the Ocean Drilling Program into sedimented young oceanic crust east of the Juan de Fuca Ridge. Data recovered over a year later showed that all four holes displayed temperature profiles indicative of vertical fluid flow immediately prior to their being sealed. Warm water was being produced from basement in two cases, and cool ocean bottom water was being drawn into basement at the others. Linear flow rates of ∼60–200 m/h were estimated from the perturbation of the temperature profiles relative to undisturbed geothermal gradients at the sites. The pressure differentials driving the flow were also measured at the time of the observatory installations, allowing estimates of permeabilities of the upper crustal sections penetrated by the holes. Estimated permeabilities vary systematically with age, ranging from about 10−10 m2 in the youngest site (0.9 Ma) to 10−12 m2 in the oldest site (3.6 Ma), confirming an apparent reduction of permeability with age determined with packer experiments at three of the same sites. Combined with other estimates of permeabilities in the same holes using methods with different scales of investigation, the new permeability estimates also provide evidence for a significant scale dependence of permeability in the upper oceanic crust.

Description: Many studies on the deep-sea benthic biota have shown that the most species-rich areas lie on the continental margins between 500 and 2500 m, which coincides with the present oxygen-minimum in the world's oceans. Some species have adapted to hypoxic conditions in oxygen-minimum zones, and some can even fulfil all their energy requirements through anaerobic metabolism for at least short periods of time. It is, however, apparent that the geographic and vertical distribution of many species is restricted by the presence of oxygen-minimum zones. Historically, cycles of global warming and cooling have led to periods of expansion and contraction of oxygen-minimum layers throughout the world's oceans. Such shifts in the global distribution of oxygen-minimum zones have presented many opportunities for allopatric speciation in organisms inhabiting slope habitats associated with continental margins, oceanic islands and seamounts. On a smaller scale, oxygen-minimum zones can be seen today as providing a barrier to gene-flow between allopatric populations. Recent studies of the Arabian Sea and in other regions of upwelling also have shown that the presence of an oxygen-minimum layer creates a strong vertical gradient in physical and biological parameters. The reduced utilisation of the downward flux of organic material in the oxygen-minimum zone results in an abundant supply of food for organisms immediately below it. The occupation of this area by species exploiting abundant food supplies may lead to strong vertical gradients in selective pressures for optimal rates of growth, modes of reproduction and development and in other aspects of species biology. The presence of such strong selective gradients may have led to an increase in habitat specialisation in the lower reaches of oxygen-minimum zones and an increased rate of speciation.

Description: We present the results of a series of experiments that examined the effect of feeding history on the growth and tissue composition of juveniles of two tropical cephalopods; the squid Sepioteuthis lessoniana and the cuttlefish Sepia elliptica. Juveniles were reared in individual containers for between 35 and 42 days at different ration levels, three ration levels for the squid and two levels for the cuttlefish. Although differences in ration were sufficient to cause different growth rates, both in body length and mass, the effects on tissue composition were less definitive. Sepioteuthis juveniles on the highest rations had higher concentrations of water, but no difference in lipid, carbohydrate or protein when compared with their lower ration siblings. In the case of juvenile cuttlefish no difference in tissue composition was detected between the two ration levels. RNA:protein ratios were also determined for the juveniles to provide an estimate of instantaneous growth. A significant correlation was found between body size and RNA:protein ratio in the squid; those juveniles that ate more had higher RNA:protein ratios than lower ration individuals. Significantly, the juvenile cuttlefish showed no relationship between growth rate and RNA:protein ratios, which means that we are unable to use this measure to estimate the growth rates of wild individuals. In conclusion, ration level did affect growth rates and food availability is an important factor in modifying growth rates of wild individuals. However, we could not find, at the individual level, an index or measure that could be used to explain the variability of observed differences in growth rates as a function of nutritional history.

Description: This study describes the age and growth of large specimens of the jumbo squid Dosidicus gigas that supported the fishery in the Gulf of California in 1995–1997. Statoliths of 299 females (10.8–87.5 cm mantle length, ML) and 147 males (17–73.9 cm ML) were read. Assuming a daily rhythm of statolith deposition the smallest female (10.8 cm ML) was 84 days old and the largest (87.5 cm ML) 386 days old. The oldest females were 14–15 months old. The smallest male (17 cm ML) was 135 days old and the oldest male (71.5 cm ML) was 372 days old. The logistic model best described growth in jumbo squid. Growth curves were similar to those reported from other studies on this species using statolith reading. However, they suggest a faster growth than that described by size frequency analysis. No differences in growth were noted between seasons, except that females from Sta. Rosalia weighed more than those caught off Guaymas at the same age. Females grew faster than males, but both sexes grew more than 2 mm/day between 140th and 300th day of life: one of the highest absolute growth rates recorded so far for squids. Large size females mature late, at an age of 1 year and 73 cm ML and males matured at 10 months and 60 cm ML. Females of the medium-sized maturing group mature at 7 months and 37 cm ML and males at 7 months and 34 cm. Thus, this latter group was regarded as an early maturing group, living probably less than a year, and the former as a late maturing group, living a year or slightly more. Hatch dates were distributed throughout the whole year, without reflecting any reproductive pattern. Large jumbo squid in the Gulf of California comprised a population of multiple intra-annual cohorts using alternate upwelling seasonal areas during their growth.

Description: Only five species of sharks have been recorded in the Southern Ocean, where their biology is essentially unknown. We investigated the feeding habits of the three commonest species from stomach content analysis of specimens taken as bycatches of the fishery targeting the Patagonian toothfish (Dissostichus eleginoides) in upper slope waters of the Kerguelen Archipelago. The three species prey upon a diversity of fishes and cephalopods. They segregate by feeding on different species of squids of different sizes. The small lanternsharks (Etmopterus cf. granulosus; 0.3 m on average) feed on small-sized Mastigoteuthis psychrophila, while the large porbeagles (Lamna nasus; 1.9 m) feed on small-sized histioteuthids (Histioteuthis atlantica and H. eltaninae) and on medium-sized juvenile ommastrephids of the genus Todarodes. Finally, the huge sleeper sharks (Somniosus cf. microcephalus; 3.9 m) prey upon large-sized cephalopods (Kondakovia longimana and Taningia danae) and giant squids (Mesonychoteuthis hamiltoni and Architeuthis dux). Thus sleeper shark is a fish with sperm whale-like feeding habits and, hence, the second top predator known to science to rely significantly on giant squids. Prey species and biology indicate that porbeagles are pelagic predators in the entire water column, while sleeper sharks are mainly benthic top predators and scavengers. The present study also underlines the diversity and biomass of the poorly known cephalopod fauna, including giant squids, occurring in outer shelf and upper slope waters surrounding subantarctic islands.

Description: Three feeding experiments, using live mysid shrimp, grass shrimp or fish fry as prey for 1-, 30- and 60-day-old cuttlefish were conducted to determine the efficiency of each dietary source in relation to cuttlefish size and age. Additionally, a fourth experiment using fish fry and grass shrimp, but previously frozen, was also conducted. The results showed that when 1-day-old cuttlefish were fed mysids, grass shrimp or fish for 4 weeks, mysids were the best prey, but only during the first week. From this moment until the end of the experiment, the best growth rate was when cuttlefish were fed grass shrimp. Cuttlefish fed fish fry showed the poorest growth rate throughout the experiment. Similarly, cuttlefish aged 30 or 60 days fed grass shrimp or fish fry had the best growth rates when fed grass shrimp. When cuttlefish were fed live fish, survival increased with size of cuttlefish (73.3%, 91.7% and 100% for 1, 30 and 60 days cuttlefish, respectively). In the fourth experiment, using frozen diets, overall acceptance of each diet (feeding rates) was the same for fish and shrimp. However, lower growth was obtained when cuttlefish were fed fish compared to grass shrimp. This lower growth was due to a lower food conversion (28% vs. 41%). Since cephalopod paralarvae and juvenile most likely need prey rich in polyunsaturated fatty acids (PUFA), phospholipids and cholesterol, and a moderate content in neutral lipids, we have analyzed the biochemical compositions of the different prey to evaluate the influence of this factor on growth and survival.

Description: We analyse the cephalopod–parasite systems taking into account the abiotic and biotic factors that may affect the host risk of infection (contact) with parasites. On the basis of 2000 individuals comprising 10 cephalopod species collected at a microgeographic area (Galician waters, NW Spain), an attempt is made to find associations between parasite relative species diversity (RSD) and cephalopod life cycle characteristics. Additionally, an index of similarity and the ratios of adult/immature (A/I) and specialist/generalist (S/G) regarding the parasite condition were used to define cephalopod ecological groupings at those species with similar risk of becoming infected with a given parasite fauna. Results show the existence of three ecological groupings (coastal, intermediate, and nerito-oceanic), which suggest that the ecological niche of a cephalopod species is more important in determining its risk of parasitic infection than is phylogeny.

Description: This paper describes the history of cephalopod fisheries in Chile over the past 40 years. Continuous monitoring of three species was undertaken between 1978 and 1999: Loligo gahi, Dosidicus gigas and Octopus mimus. Total cephalopod catches increased from 69 tonnes in 1978 (0.13% total mollusc catch) to 3503 tonnes in 1996 (3.64%). A maximum haul of 15,169 tonnes was taken in 1992 (11.27% total mollusc catch). Small-scale fisheries accounted for the majority of cephalopod captures and industrial catches were rare. L. gahi is caught year-round mainly in the south of Chile, with maximum catches in summer and autumn. Catches of D. gigas are also year-round, mainly concentrated in central Chile. O. mimus has been fished since 1978, although recorded as Octopus vulgaris until the 1990s. The O. mimus fishery is located on the north coast of Chile, and catches are made for the most of the year. Octopus has been landed in the south of Chile since 1991, and is considered as O. mimus in capture statistics despite the fact that several species are represented, including Enteroctopus megalocyathus.

Description: Explosive activity at Mt. Etna from July 19 to August 7, 2001, provides a good case study to investigate the causes of the transitions between style of basaltic explosion. In this period, a new vent, located at 2550 m above sea level on the southern flank of the volcano, exhibited three types of activities that followed one another: initial ash and steam explosions with the emission of radial jets, of hydromagmatic origin; intermediate fire fountaining and Strombolian explosions, due to magma vesiculation; and finally, sustained to pulsing ash explosions, caused by overpressurization of the degassed and cooling top of the magma column. The activities produced two end-members of juvenile ash in the size range 0.4–0.1 mm: (1) brown, fluidal- to irregular-shaped, vesicular sideromelane glass particles, and (2) microcrystalline, blocky, poorly vesicular tachylite particles. Component analysis of the ash reveals a gradual decrease in the abundance of sideromelane, replaced by tachylite, in the transition from the Strombolian to the final ash explosion activity. Dense blocks with irregular, variable surface textures also characterize the products of the late pulsing ash explosions. Petrographic, chemical, and crystal size distribution analyses, together with morphological evidences, indicate that sideromelane quenched earlier than tachylite during the final stage of magma evolution. In fact, the groundmass of tachylite formed by subsequent crystallization of magma, possibly at lower temperature and under different degassing conditions. We hypothesize that sideromelane formed in the central part of the volcanic conduit, where the buoyant rise of gas bubbles caused a higher magma ascent velocity, which did not allow time for vesicle to escape or collapse before fragmentation. Conversely, tachylite crystallized at the margins of the conduit, where slow-moving magma accumulated, temperature was lower, and vesicle collapsed, forming a network of cracks favorable to permeable gas flow. Reduced magma emission rate at the end of the Strombolian phase caused an increase in the thickness of the peripheral degassed magma zone, until it formed a plug at the top of the conduit, and activity gradually shifted to pulsing ash explosions. These were driven by repeated explosions of the overpressurized plug, in a small-scale, vulcanian-like, explosive process. We suggest that the relative abundance of sideromelane and tachylite ash particles in basaltic explosion products may provide information on the evolution of velocity gradients within magma flux.

Description: The Illex illecebrosus fishery in the northwestern Atlantic Ocean is trawl-based. I. illecebrosus normally lives less than 1 year. One option for managing such a short-lived species is the use of catch and effort data obtained from fishing vessels during the fishing season to manage the fishery in real time. Verification of the accuracy of data reports is important. Conceivably, information contained in the data stream of vessel position and time provided by a remote data logger could be used to reconstruct the vessel’s activities to assess the reliability of industry reports. This study describes quantitatively the types of vessel operating activities that take place on a typical I. illecebrosus fishing trip and assesses the possibility of reconstructing these activities reliably from the simple data stream of vessel position and time. Seven activities were identified, six of which occurred commonly: steaming to and from port, searching, towing, set-up time between tows, steaming overnight and laying-to overnight. Processing the catch, as a discrete activity, occurred rarely. Each activity could be characterized in terms of its duration and distance traveled, the average vessel speed, and the tendency for vessel speed to change during the activity. Most activities were conducted in a linear manner. Accordingly, reasonable estimates of the distance and duration of these activities could be obtained simply from the knowledge of the starting and ending position and time. Analysis of search time and subsequent catch revealed that searching did not improve catch. More squid would have been caught had the vessels used this time for towing. Catch per unit effort (CPUE) can be calculated using duration or distance in the denominator. In this set of fishing trips, the two were equivalent. Catch bore a nonlinear relationship with CPUE. In particular, larger catches were associated with incrementally larger CPUEs. The uniqueness of each activity when described by its characteristic speed, duration and distance, and the consistency of these characteristics for each activity between vessels suggests that vessel behavior might be assessed remotely using a time series of position and time. Such a capability might be important in any real-time management plan where industry vessels necessarily must be depended upon for data on catch and CPUE.

Description: The combined effects of photoperiod and feeding frequency on survival and growth of juvenile cuttlefish has been studied in experimental rearing. During juvenile cuttlefish growth, survival and growth rate were low when the photoperiod was short (8 h of light and 16 h of dark). Increased frequency of diet did not stimulate the appetite of animals reared in normal or long photoperiod (16 h of light and 8 h of dark). However, by studying the combined effects of photoperiod and feeding frequency, we have demonstrated that an increase in feeding frequency can enhance survival and growth in the group receiving the shortest period of light per day. Temperature is an important factor in the regulation of the incubation period of eggs and of growth after hatching, but it also appears in this investigation that the combined effect of photoperiod and feeding frequency must be considered during growth of juvenile cuttlefish.

Description: The neon flying squid, Ommastrephes bartramii (Lesueur), is a widespread subtropical to temperate species, and is composed of several tempo-spatial groups in the North Pacific. We analyze the growth parameters of two allopatric stocks with two seasonal cohorts using statolith microstructure, and propose a tempo-spatial migration model. We used 571 statoliths, obtained from juvenile/adult squids (175–527 mm mantle length, ML). Based on precise digitized statolith growth marks, various early life demographic traits were estimated by the back-calculation method. Two cohorts of autumn and winter were identified in the northeastern (NE) North Pacific, while only a comparable winter cohort was found in the northwestern (NW). There was a significant difference in the relationships of statolith radius (Ra) to increment numbers (In) between NE and NW stocks. However, linear ML to Ra relationship exhibited no geographic difference in large females (〉350 mm ML), but significant difference between NE and NW in both small females (〈350 mm ML) and males. Growth in length (ML) at week (t) is best fitted by a power function of innate growth for NE small females and males, and NW large females; however, the Gompertz function of decreasing growth rate is better for NE large females, and NW small females and males. Variations on demographic traits confirm two geographic stocks of NE and NW, and two seasonal cohorts of NE stock. Indistinguishable growth parameters shown by NE and NW large females suggest a longer life history of the population, which migrates across the geographic boundary at a longitude of 170°E. The ambient temperature, that corresponding to their early life stages, could be a plausible factor in later growth difference.

Description: We investigated the stomach contents of Dall's porpoises collected in pelagic waters spanning most of their range in the North Pacific and the Bering Sea. Analysis revealed the porpoises fed mainly on myctophid fishes in the subarctic North Pacific and on gonatid squids as well as myctophid fishes in the Bering Sea. Most of the prey items were mesopelagic micronekton, primarily fishes and squids that migrate vertically to shallower waters at night. Stomach content was greater during twilight hours, suggesting the porpoises foraged actively on myctophids at night in shallower waters. Stomach contents were strongly characterized by local mesopelagic prey fauna, and prey species selectivity was not apparent. The annual consumption by Dall's porpoises was estimated to be 2.0–2.8 million tons, or 4.7–6.5% of the biomass of mesopelagic fishes in the subarctic North Pacific, and may account for approximately 24–33% of the overall mortality of mesopelagic micronekton, especially myctophids. Myctophids are also common, but less important, prey of other subarctic predators. Dall's porpoises are likely the primary consumers of myctophids in the subarctic North Pacific. Since myctophids are the major component of the mesotrophic level, the trophic relationship between myctophids and Dall's porpoises is thought to be an important pathway of mass and energy in the pelagic food web in the subarctic North Pacific.

Description: Fishery statistics for two abundant commercial squid, Illex argentinus (Ommastrephidae) and Loligo gahi (Loliginidae), in Falkland Islands waters (southwest Atlantic) between 1987 and 1999 were analysed. The areas of the highest densities of the two species are usually separated, with I. argentinus most abundant to the north-west of the Islands in February–May and L. gahi to the south-east in February–May and August–October. However, in some years, I. argentinus intrude in great numbers into nursery or feeding areas of L. gahi in April and May. It could, therefore, affect, either directly (via predation) or indirectly (by competition for food), the abundance and recruitment of the second cohort of L. gahi, exploited around the Islands between April and October. Catch per unit effort (CPUE) of I. argentinus in February–March did not correlate with that of L. gahi in February–May. In contrast, the CPUE of I. argentinus in April–May was negatively correlated with that of L. gahi in April–May and August–October of the same year. Possible reasons for these inverse abundance patterns of the two squid species, and their implications for fisheries management are discussed.

Description: In the Falkland waters, squid have maximum stomach fullness and lowest hunting activity in the evening. During the night, hunting activity increased until dawn while food was digesting, except for a short period around and after midnight when squid activity decreased.

Description: The influence of both predator and prey size on the shift from a pulling to a drilling predatory response was examined in the intertidal octopus Octopus dierythraeus, using an experimental program. Additionally, selective drilling, where particular regions of the prey are targeted, was examined for a variety of bivalve and gastropod prey. O. dierythraeus always initially attempted to pull bivalves apart. Shells that were eventually drilled were always subjected to significantly more pulling attempts than those that could be pulled apart, indicating that octopus are willing to expend more energy to access the flesh quickly. There was no defined threshold where bivalve size caused an octopus to switch from a pulling to a drilling response. Instead, there was a broad size range where the octopus could adopt either handling method and it varied for each individual. Octopus may only able to pull open bivalves before the molecular ratchet or ‘catch’ mechanism that many bivalves possess is engaged. This might explain the lack of a relationship between either octopus or bivalve size and the success of pulling, as it is likely that when the bivalves were presented to individual octopus they were either setting the ‘catch’ mechanism, or had already engaged it. O. dierythraeus demonstrated selective drilling on a variety of molluscan prey, with penetration sites differing between prey species. O. dierythraeus targeted the valve periphery, which was the thinnest part of the shell, therefore minimizing handling time. O. dierythraeus always drilled gastropods, but did not target the thinnest regions of the shells, with drill site varying according to the morphology of the prey. Elongate species with pronounced aperture lips were drilled in the apical region, close to the columella on the side of the opercula whereas nonelongate species were drilled immediately above the aperture. The location of drilling sites may represent a trade-off between targeting the most effective places to inject paralyzing secretions and the mechanically simplest places to drill.

Description: Cephalopods constitute a valuable resource of Portuguese fisheries, but there are no data on the adequacy of legal mesh size with regards to minimum landing size (MLS) (or weight). In the autumn of 1998 and the spring and summer of 1999 surveys were carried out off the northern coast of Portugal to study codend selectivity of finfish bottom trawls. Mesh sizes used were 65, 80 and 90 mm (full mesh size). During these surveys primarily targeting fish species, data were obtained for the octopus, Octopus vulgaris, the European squid, Loligo vulgaris and the broadtail shortfin squid, Illex coindetii. For the octopus, selectivity parameters were estimated for the 65 mm codend (L50 between 8.4 and 9.7 cm and selection factor (SF) 1.3 and 1.5) and for the 80 mm codend in the summer (L50 14.2 cm and SF 1.9). For the European squid, selectivity parameters were estimated in the autumn survey for the 80 and 90 mm mesh size codends (L50 9.7 and 11.4 cm, respectively, and SF 1.3 for both codends). For the broadtail shortfin squid, selectivity parameters were estimated in the summer for the 65 mm mesh size codend (L50 9.5 cm and SF 1.5). Considering that the finfish bottom trawl fishery uses a minimum mesh size of 65 mm, it is concluded that a high proportion of small octopus that has a minimum landing weight (MLW) of 0.75 kg (corresponding to a dorsal mantle length of 11.8 cm) is retained. For the European squid, whose MLS is 10 cm, a 65 mm mesh size would also retain an extremely high proportion of undersized individuals, but these occur in very small numbers in the fishery. The broadtail shortfin squid has no established MLS.

Description: Population structure and reproductive patterns of the long-finned squid Loligo plei off the coast of Santa Catarina, southern Brazil, were analysed from the biological samples of commercial catches landed in the Itajaı́ harbour from April 1995 to February 1998. The species were recruited to the trawl fishery at 130 mm mantle length (ML) and males were, on average, nearly 1.3 times larger than females. The exponents of males and females ML–weight relationships were 1.89 and 2.07, respectively, and differed significantly between maturity stages. Cohorts of both sexes did not persist into their second year, a feature that, coupled with the scarcity of spent animals, provided evidence for semelparity with nearly 1 year life span. An extended seasonal breeding and spawning pattern was characterised with a large reproduction event concentrated during the summer months extending through autumn and winter. It is suggested that the summer spawners hatch during the summer–early autumn, recruit to the fishery in the spring and reach maturity in the following summer, at the age of nearly 1 year. Squid spawned during the winter will hatch during winter–early spring, recruit to the fishery during the summer and autumn and spawn in their second winter. Between summer and winter spawning events, continuous spawning activity produce several microcohorts detected in trawlers catch. Summer spawners sustain the most important commercial concentrations. The relationship between L. plei population structure, seasonal abundance and the dynamics of environmental conditions off southern Brazil is discussed.

Description: An assessment of the South African chokka squid Loligo vulgaris reynaudii fishery is undertaken. Two fisheries catch chokka: the directed jig and the trawl fishery. Chokka is a by-catch in the latter fishery, which targets primarily Cape hake (Merluccius spp.) and Agulhas sole (Austroglossus pectoralis). A population dynamics model is fitted to the jig and trawl CPUE indices, and two biomass indices from scientific surveys, by means of an observation-error estimator. The dynamics are modelled for two periods: January–March and April–December. Parameters estimated are the annual recruitment R and the catchability coefficients corresponding to each biomass index; a composite somatic growth and mortality parameter, g, is fixed externally. Within this approach, two models for annual recruitment are considered: (A) recruitment is constant above a biomass threshold, below which it starts to decline; (B) recruitment depends on jig-induced fishing mortality, larger values of which have an increasing negative impact on reproductive success. The parameters estimated for model A have wide confidence intervals and the model is unable to fit the decline in the early years of the trawl CPUE time-series. A better fit is achieved for the approach taken in model B. The linkage in this model of declines in recruitment to disturbance caused by the jig fishery is, however, somewhat ad hoc, and a basis for an independent test of this link is suggested. Model B estimates the current biomass to be heavily depleted. Stochastic projections under the assumption that the current effort level is maintained, show that the risk of the spawning biomass falling below 20% of its pristine level over the next 10 years is close to 90%. Effort needs to be cut to 2/3 of that at present to achieve a substantial reduction in this level of risk. Some alternative scenarios that are investigated, such as that of a non-linear relationship between jig CPUE and biomass, give more pessimistic results.

Description: The feeding habits of Beryx splendens and B. decadactylus were determined from stomach contents obtained on a monthly basis during commercial fishing off the Canary Islands in 1996–1997. Changes in diets were studied in relation to predator size and seasonal variation in the food composition. The diet of both species has much in common with regard to its main components of small fishes, crustaceans and cephalopods. More important differences were found in the fish prey of B. decadactylus. A variation in the diet of B. splendens was observed according to its length. Seasonal variations in feeding habits were associated with either variations in the abundance of prey or variations in the depth distribution of predator and prey.

Description: Phylogenetic relationships among the cirrate octopods (Mollusca: Cephalopoda) were investigated using partial sequences of the 16S rRNA mitochondrial gene. The derived phylogeny supports the traditional separation of cirrate families based on web form. Genera with a single web (Opisthoteuthis, Grimpoteuthis, Luteuthis, and Cirroctopus) are clearly distinct from those with an intermediate or secondary web (Cirroteuthis, Cirrothauma, and Stauroteuthis). The cirrates with a single web are separated into three groups. The first group is represented by Opisthoteuthis species, the second by Grimpoteuthis and Luteuthis, and the third by members of the genus Cirroctopus. There is no support for the isolation of Luteuthis in a separate family (Luteuthidae). There is, however, evidence of two groupings within the genus Opisthoteuthis. The data suggest the following revisions in the systematic classification of the cirrates: (1) Cirrothauma, Cirroteuthis, and Stauroteuthis be united in the Cirroteuthidae; (2) Grimpoteuthis and Luteuthis be placed in the Grimpoteuthidae; (3) Opisthoteuthis in the Opisthoteuthidae, and; (4) Cirroctopus be considered sufficiently distinct from both Opisthoteuthidae and Grimpoteuthidae to warrant placement in a new family.

Description: Experiments were conducted to investigate growth and proteolytic activity of the common octopus Octopus vulgaris, reared with different diets and ration levels during first feeding. Four ration levels were tested, 0.2, 2, 4 and 10 Artemia nauplii ml−1 day−1 and co-feeding techniques were tested using 10 Artemia nauplii ml−1 day−1 plus three different compound millicapsules. Total proteolytic activity, trypsin and chymotrypsin levels were recorded from eggs, hatchlings and during the first month of paralarval rearing. Five days after hatching, paralarval weight and proteolytic activity was dependent on food ration. The low-food treatment did not lead to an increase in hatchling weight, in contrast with the positive increase of the other treatments. After 20 days, best survival was observed in treatments fed 2 and 4 nauplii ml−1 day−1. High nauplii rations of 10 nauplii ml−1 day−1 plus millicapsule diet treatments produced higher growth and higher proteolytic, trypsin and chymotrypsin levels, but poor survival. Total proteolytic activity was correlated with paralarval weight, whereas trypsin and chymotrypsin were maintained at hatchling levels only for the high food and co-feeding treatments, and decreased in the others. The trypsin activity in the high-food treatment showed a sharp increase after 15 days and 880 μg of the mean dry weight (2.5 times hatchling weight). Millicapsules were ingested by the paralarvae after 5 days but did not lead to a significant increase in weight. Enriched Artemia nauplii seem to be useful only as an initial diet until a doubling in hatchling weight is achieved. This period can extend from 11 to 14 days at 20 °C, after which a larger prey and/or suitable microdiet is required.

Description: Several species of migratory, warm-water, oceanic fishes invaded Oregon waters during the summer of 1997. Also, the jumbo squid (Dosidicus gigas), common in the eastern tropical Pacific, was reported for the first time in 1997 and was caught in large numbers. The occurrence of these oceanic nekton was associated with inshore advection of anomalously warm water. During 1998, after arrival of the main El Niño signal, some warm-water coastal fishes appeared off Oregon. However, unlike observations off California, fewer species of warm-water coastal fishes were noted during the 1997–98 El Niño than during the 1982–83 El Niño.

Description: A mollusc shell, the xiphoid from cuttlefish was found to be a substrate favouring the deposition of aragonite crystals from stable supersaturated solutions at pH 8.50 and 25°C. The crystallization was studied at constant solution composition, thus making it possible for a relatively large amount of the overgrowths to be formed and to be identified exclusively as aragonite crystals. The apparent order found from kinetics data was n=4.1±0.4, thus suggesting a polynuclear mechanism. A surface energy of 24±3 mJ m−2 was calculated for the growing phase and a four-ion cluster forming the critical nucleus, according to the classical nucleation theory.

Description: A shared characteristic among animals is their propensity to form stable, beneficial relationships with prokaryotes. Usually these associations occur in the form of consortia, i.e. a diverse assemblage of bacteria interacting with a single animal host. These complex communities, while common, have been difficult to characterize. The two-partner symbiosis between the squid Euprymna scolopes and the marine luminous bacterium Vibrio fischeri offers the opportunity to study the interaction between animal and bacterial cells, because both partners can be cultured in the laboratory and the symbiosis can be manipulated experimentally. This system is being used to characterize the mechanisms by which animals establish, develop and maintain stable alliances with bacteria. This review summarizes the progress to date on the development of this model.

Description: The common octopus, Octopus vulgaris Cuvier, 1797 is the most important cephalopod species in catches of the artisanal trap fishery in Canary Islands waters. Based on monthly samplings carried out off Gran Canaria (Canary Islands), 760 specimens of the common octopus, ranging from 4.8 to 165 mm ventral mantle length, were studied from June 1996 to July 1997, and from December 1997 to June 1999. The length–weight relationships found were W=0.0007×VML3.096 (n=760;r=0.95), W=0.0007×VML3.112 (n=481;r=0.86), W=0.0007×VML3.098 (n=247;r=0.77), for all the specimens caught, males and females, respectively. The proportion of males was significantly higher than females. Males predominated in all size intervals. Males and females become sexually mature at 105 and 113 mm of VML, respectively. Maturation and spawning occur all year around, with more intensity from January to July, with a peak in April. There is a second spawning period in October–November. The number of spermatophores produced increased with length and maturity stage. The production of spermatophores by individual body weight fluctuated from 0.29 to 0.03 spermatophores/g. The number of oocytes per gram of body weight fluctuated from 108 to 465. The real fecundity oscillated between 31 and 106 eggs spawned per gram of female body weight.

Description: Juvenile cuttlefish hatched in the laboratory were reared for 30 days with different enriched diets, in spring and in summer. The groups fed an enriched natural diet exhibited a high rate of survival even when seawater quality decreased during the summer. The natural diet enriched in polyunsaturated fatty acids (PUFA) induced faster growth in juvenile cuttlefish; the stimulating effect of PUFA on growth was evident during the very early juvenile stage, and the benefit resulted is conserved during further growth. The maximum daily ration was lower in groups fed with the enriched diet than in the control. These data indicate the importance of n−3 PUFA such as docosahexaenoic acid (DHA; 22:6n−3) and eicosapentaenoic acid (EPA; 20:5n−3) in cephalopod juvenile nutrition.

Description: The composition and distribution of squid captured between January and March during the 1996 baseline research on oceanography, krill and the environment survey off East Antarctica (80–150°E) was investigated. A total of 195 individuals were captured. The species collected were Galiteuthis glacialis, Mesonychoteuthis hamiltoni, Histioteuthis atlantica, H. eltaninae, Alluroteuthis antarcticus, Batoteuthis skolops and Pholidoteuthis boschmai. Concentrations of squid were low, ranging from 4.4 to 174.7 individuals 100,000−3. The majority of squid captured were G. glacialis (174 individuals, 89.2% of all squid captured), and most of these (n=171) were small paralarvae 〈25 mm in mantle length. G. glacialis were distributed predominantly west of 120°E in water that was colder, and where the distance from the coastline of the southern boundary of the Antarctic circumpolar current (SB-ACC) was maximal. This water mass had greater concentrations of phytoplankton, was more productive and had maximal sea-ice extent compared to the water mass east of 120°E. G. glacialis was therefore more abundant in water where the majority of krill and krill predators were present compared to warmer oceanic waters of the ACC to the east, where salps dominated.

Description: In order to provide a tool for the prevention of commercial frauds in fish products, a simple polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method has been developed. This method allows to clearly differentiate molluscs belonging to the family Loliginidae from those belonging to the family Ommastrephidae. Cephalopods' 16S r-DNA was amplified with PCR using a “universal” primer pair, and the amplification product was digested with AsnI restriction enzyme. The resulting electrophoretic patterns of families Loliginidae and Ommastrephidae showed characteristic 200 bp band and 600–700 bp band, respectively. With this methodology, the analysed species belonging to the genus Loligo have also been differentiated.

Description: The high concentrations of cadmium recorded in the digestive gland of cephalopods from various temperate and subpolar waters suggest that these molluscs have developed efficient cadmium detoxification mechanisms. The subcellular distribution of cadmium in the digestive gland cells was investigated in seven cephalopod species from the Bay of Biscay (France) and the Faroe Islands. In most species, cadmium was mainly found in the cytosolic fraction of the digestive gland cells, reaching up to 86% of the total cadmium for the squid Loligo vulgaris from the Bay of Biscay. But species with the highest total level of cadmium showed a higher percentage of cadmium associated to insoluble compounds. The quantification of metallothioneins (MTs) by the polarographic method was performed in order to evaluate the involvement of these proteins in the detoxification of the high amounts of bioaccumulated cadmium. Metallothionein levels in cephalopods ranged form 742±270 to 3478±1572 μg/g wet weight. No relationship could be established between total cadmium, cytosolic cadmium and MT levels suggesting the occurrence of other Cd-binding ligands. Although these proteins have not been characterised, as cadmium in the digestive gland of cephalopods is mainly associated with soluble ligands, a high potential transfer to predators can be predicted.

Description: In this paper we examine the phylogenetic relationships of the Octopoda utilizing molecular sequence data from the cytochrome c oxidase subunit I (COI) gene and compare results from analyses of molecular data with classifications and phylogenies based on previous morphological studies. Partial COI sequences (657 bp, excluding primers) were obtained from 28 species representing most of the diversity in the Order Octopoda, along with a sequence from the established sister taxon to the Octopoda, Vampyroteuthis infernalis. Our results exhibit a number of basic differences from inferences based on standard morphological data. We attempt to resolve these differences based on our confidence in various morphological features. An important finding is the failure of the molecular data to support the monophyly of the Octopodidae. This family contains over 90% of the species in the Suborder Incirrata and has always been difficult to define. Statistical tests constraining Octopodidae monophyly by use of parsimony and maximum-likelihood techniques suggest that all incirrates may be derived from octopodids.

Description: Stages of merogony of a coccidian parasite were commonly observed during histological examination of the digestive tract of 7 crustacean species from Galician coastal waters. Study of the fine structure of these merogonial stages by transmission electron microscopy revealed the presence of a typical apicomplexan apical complex. Newly hatched Sepia officinalis obtained from egg masses, cultured in 3 separate tanks, were fed with three parasitised prawn species in infection experiments. Cuttlefish fed with Palaemon elegans and P. adpersus developed sexual stages and sporocysts diagnostic of Aggregata eberthi, identifying these prawns as new intermediate hosts of this parasite. No infection was found in Sepia fed with P. serratus, suggesting that this prawn could be an intermediate host of another species of Aggregata. By experimental infections of cultured cuttlefish, achieved here for the first time, the complete life cycle of A. eberthi in Spanish NE Atlantic waters was established.

Description: The complete amino acid sequence of squid Todarodes pacificus troponin C (TnC), which was shown to bind only 1 mol Ca2+/mol, was determined by both the Edman and cDNA methods. The squid TnC is composed of 147 amino acids including an unblocked Pro at the N-terminus and the calculated molecular weight is 17 003.9. Among the four potential Ca2+-binding sites, namely sites I–IV from the N-terminus, only site IV completely satisfied the consensus amino acid sequence for the active Ca2+-binding loop. This indicates that squid TnC possesses a single Ca2+-binding site at the site IV as scallop TnCs [Nishita et al., J. Biol. Chem. 269 (1994) 3464–3468; Ojima et al., Arch. Biochem. Biophys. 311 (1994) 272–276). The sequence homology of squid TnC to TnCs of scallop, arthropods, and rabbit was 61%, 31–38%, and 31%, respectively. In the sequence of the central D/E-helix region of squid and scallop TnCs, a deletion of three amino acids was required to maximize the homology with the other TnCs.

Description: The thermal infrared data from the satellites of the European Meteosat series are used to characterize the dynamics of the West African coastal upwelling for the period 1984–1998. Sea surface temperature (SST) images are produced from satellite data with a spatial resolution of 5 km and a time-step of 5 days. These are used to characterize the spatial structure of the upwelling by automatic localisation of the SST minima at each coast location and to derive a normalised upwelling intensity index, based on SST differences. A new index for retention potential is also proposed. The strong interannual variability observed in these indices is quantified, mainly in terms of intensity and seasonal lag. An objective method of space partitioning, based on the variability of the proposed indices is introduced. Objective analysis applied to three characteristic regions shows that the spawning areas of the coastal pelagic species may be clearly delineated in terms of spatial and temporal optimisation of enrichment and retention processes. The importance of the retention processes is shown for the recruitment of Sardinella aurita in Senegal and for Octopus vulgaris in Mauritania. According to the concept of Bakun's triad for upwelling areas, a precise determination of the upwellings intensity and associated spatial processes is essential for evaluating the balance between enrichment and its optimal use in an ecological sense. A Java-based software package is produced as part of this study to visualise long series of pre-processed images and to extract the above indices.

Description: Trypsin inhibitor was purified from the hepatopancreas of squid (Todarodes pacificus). The final inhibitor preparation was nearly homogeneous by SDS-PAGE with an estimated molecular weight of approximately 6300. The squid trypsin inhibitor was acid- and heat-stable, and active against trypsins from the pyloric ceca of starfish (Asterias amurensis) and saury (Cololabis saira) and porcine pancreatic trypsin. Amino acid composition of the squid trypsin inhibitor was compared with other invertebrate trypsin inhibitors. The squid trypsin inhibitor inhibited the autolysis of walleye pollock (Theragra chalcogramma) myofibrillar proteins.

Description: Loligo gahi were collected from bottom trawl samples taken around the Falkland Islands on both commercial and research vessels from January 1994 to November 1995. Commercial samples were taken from both seasons of the fishery (February–May, August–October), research samples were taken in January, June and November. A sub-sample of squid was taken from each sample to provide statoliths for age determination by statolith increment analysis. Sea surface temperature data were derived for an area encompassing the southerly portion of the fishing grounds for L. gahi to provide an indicator of seasonal temperature variations for that region. Age data were derived for 486 females and 445 males. Exponential and power growth models explained the fit to the size-at-age data to a similar extent. Age data were grouped by month and by season of hatch to test the hypothesis that seasonal temperature variability influences the size-at-age relationship in L. gahi. Analyses of covariance showed that the relationships of both predicted mean mantle length and predicted mean body mass per month of hatch, and per season of hatch resembled closely the trends in mean monthly sea surface temperature, with the squid hatched in the summer, i.e., at higher temperatures, being significantly larger than squid of the same age but hatched in the winter months. The growth rates for adult squid in this study were similar over the age range analysed. This study provides evidence that increased temperature during a squid’s early growth period may accelerate growth markedly giving rise to significant differences in size-at-age for adult squid hatched at different temperatures.

Description: Activities of the antioxidative enzymes superoxide dismutase (SOD), catalase, glutathione peroxidase (GPX) and glutathione reductase (GR) were measured in the cephalopods Sepia officinalis and Lolliguncula brevis. Maximal enzyme activities were higher in gill tissue than in the mantle musculature of both species. Activities were generally lower in tissues of L. brevis than in S. officinalis. Comparison with other ectothermic animals showed both cephalopod species to have a low enzymatic antioxidative status despite their high metabolic rate. Furthermore, changes in antioxidative enzyme activities were measured in the cuttlefish S. officinalis with increasing age. The concentrations of malondialdehyde (MDA) and lipofuscin were determined as indicators of lipid peroxidation. Investigated animals were between 1.5 months and over 12 months old. Changes of antioxidative enzyme activities with age were not uniform. SOD and GPX activities increased with age, while catalase activity declined. In contrast, GR activity remained almost unchanged in all age groups. The low level of antioxidative defense might allow for the significant age-induced rise in MDA levels in gills and mantle musculature and for the increase in lipofuscin levels in mantle and brain tissue. It might thereby contribute to increased oxidative damage and a short life span in these cephalopods.

Description: Soils in New Caledonia are particularly rich in metals among which Fe and Ni are intensively exploited. Due to important natural erosion in tropical latitudes and to mining activities, coastal waters are enriched in Co, Cr, Fe and Ni. In deeper waters lives a cephalopod species which is considered as a living fossil, the nautilus Nautilus macromphalus. In this study, 12 trace elements were analysed in the tissues of 4 nautilus specimens. Results showed high metal concentrations compared to data available for cephalopods from temperate waters. These concentrations were often in the same order as those encountered in bivalves or gastropods from contaminated areas. Relatively high concentrations of Ni and Cr in the haemolymph strongly suggest a high exposure of N. macromphalus to these metals. Among the tissues, the digestive gland has the highest concentrations of Cd, Co, Fe, V and Zn while for Ag, Al, As, Cr and Ni, renal and pericardial appendages exhibited the highest values. Despite this, the digestive gland contained the largest quantities of all metals with the exception of As and Mn which were mainly found in the body muscular remains. These results highlighted the major role of digestive gland and excreting organs in the metabolism of metals in these cephalopod species.

Description: The beaks of 10 cephalopod species were found in the diet of foraging and moulting king penguins (Aptenodytes patagonicus) from a breeding colony at Volunteer Beach, Falkland Islands during austral winter (September/October 1996). A total of 486 lower cephalopod beaks were collected, identified and measured (LRL: lower rostral length). Six cephalopod families occurred in the penguins’ diet with Onychoteuthidae being the most abundant (256 lower beaks) and represented by Moroteuthis ingens (168; LRL range 2.1–6.8 mm), Moroteuthis knipovitchi (79; LRL range 1.9–5.5 mm), and Kondakovia longimana (9; LRL range 2.1–7.4 mm). Other families were Ommastrephidae (135) with Martialia hyadesi (127; LRL range 2.6–8.7 mm), Illex argentinus (6; LRL range 5.0–6.0 mm), and Ommastrephes bartrami (2; LRL range 7.9–8.8 mm); Loliginidae with Loligo gahi (60; LRL range 0.8–2.1 mm); Gonatidae with Gonatus antarcticus (28; LRL range 1.3–3.3 mm); Neoteuthidae with Alluroteuthis antarcticus (4; LRL range 2.4–3.9 mm), and Histioteuthidae with Histioteuthis eltaninae (3; LRL range 3.3–3.4 mm). Allometric equations were used to relate lower rostral beak length with cephalopod body size and mass. M. ingens was the dominating cephalopod prey in terms of numbers (n=168), whereas M. hyadesi was most important in terms of biomass (64 682 g). The present study provides first information on the cephalopod prey of Falkland Islands king penguins. The data suggest that penguins take squid at coastal islands slope regions as well as in oceanic waters which demonstrates their ability to forage in a wide geographical area and to alternate between specific foraging sites. Possible competition with the commercial squid fishery off the Falkland Islands is discussed.

Description: The oxygen consumption rates and activities of key metabolic enzymes were measured and analyzed as a function of habitat depth for several species of benthic octopod (Cephalopoda: Octopoda) including a recently described hydrothermal vent endemic species. Oxygen consumption rates and citrate synthase activity, an indicator of aerobic metabolic potential, did not vary significantly with increasing habitat depth. Anaerobic metabolic potential, as evidenced by octopine dehydrogenase activity, declined significantly with increasing habitat depth. It is suggested that burst swimming abilities, and hence glycolytic potential, are not strongly selected for in the deep-sea, where visual predator-prey interactions are reduced because of light-limitation. Oxygen consumption rates for Octopus californicus and O. bimaculoides were analyzed as a function of oxygen partial pressure as well. O. californicus, which lives in the hypoxic Santa Barbara basin at 500 m depth, was able to regulate its oxygen consumption to the limit of detectable oxygen partial pressures. O. bimaculoides, an intertidal species, had a minimum critical oxygen partial pressure of 16 mmHg. It is also shown that oxygen consumption rates and oxygen consumption regulation are strongly affected by individual experiment duration (either handling stress or food deprivation). O. californicus appears to be much more strongly affected by experiment duration than is O. bimaculoides.

Description: Octopus (Octopus maya) and red grouper (Epinephelus morio) are the most important fisheries resources on the northern continental shelf of Yucatan, Mexico, with annual yields fluctuating between 9000 and 16 000 t. Octopus is an important component of the diet of red grouper, particularly when the abundance of octopus increases during summer and autumn in shallow waters. A previous mass-balanced model using the Ecopath program described the main flows of biomass in this ecosystem, with emphasis on the commercially important stocks. In this paper, a dynamic structured model of exploited ecosystems, Ecosim, is used to simulate changes in vulnerability of octopus to predation by the red grouper under three scenarios of fishing mortality (F): (1) F low and constant; (2) gradual increments in F reflecting historical development of the octopus fishery; and (3) high values of F representing the current state of the fishery. A fourth scenario is also presented, based on scenario 2, to observe biomass patterns of other groups. For all scenarios, when vulnerability of the octopus to predation was reduced, their biomass pattern was inverse to that when their vulnerability to predation increased. A similar behavior was found at high levels of vulnerability when octopus were submitted to high fishing effort. The impact of the combined effect of changes in vulnerability with fishing intensity suggests the presence of important compensatory mechanisms tending to maintain a thermodynamic stability, where growth efficiency and consumption play important roles. Even when fishing intensity appears to produce larger impact on the octopus biomass, vulnerability has an important role when it is reduced and when the stock is submitted to very high levels of exploitation. After simulations, the biomasses of octopus and red grouper exhibited a similar picture to historical catch trends, suggesting that Ecosim could provide useful guidance for fisheries managers.

Description: Two contrasting models of the dynamics of explosive basaltic eruptions are in current usage. These are referred to as the rise speed dependent (RSD) model and the collapsing foam (CF) model. The basic assumptions of each model are examined, and it is found that neither model is flawed in any fundamental way. The models are then compared as to how well they reproduce observed Strombolian, Hawaiian and transitional eruptive behaviour. It is shown that the models do not differ greatly in their treatment of Strombolian eruptions. The models of Hawaiian eruptions are, however, very different from each other. A detailed examination of the 1983–1986 Pu'u ‘O’o eruption finds that the CF model is inconsistent with observed activity in a number of important aspects. By contrast, the RSD model is consistent with the observed activity. The issues raised in the application of the CF model to this eruption draw into doubt its validity as a model of Hawaiian activity. Transitional eruptions have only been examined using the RSD model and it is shown that the RSD model is able to successfully reproduce this kind of activity too. The ultimate conclusion of this study is that fundamental problems exist in the application of the CF model to real eruptions.

Description: Estimates of ages for short-finned squid (Illex illecebrosus LeSueur) were derived from two different methods for preparing statoliths and enumerating daily increments. Each pair of statoliths was divided between two experienced agers. One (Ager B) ground the statoliths on one side in the frontal plane for examination by light microscopy with camera lucida. The other (Ager G) ground statoliths on two sides in the sagittal plane for examination by light microscopy with an image analysis system. Mean counts of increments did not differ between the two agers reflecting similar peak hatching periods and patterns of migration. Systematic differences were, however, evident in that counts by Ager G were larger in young squid and smaller in old squid than those by Ager B. Crossing of methods suggested that estimated age was affected by the method of preparation of statoliths, but bias between agers was primarily due to differences in methods of interpreting and enumerating increments. This bias greatly affected estimates of growth rates. Rates of growth of groups obtained by the two agers based on the estimated month of hatching were compared with those of individual gladii. Such comparisons failed to identify which method was the more reliable because of small sample sizes and poor fit of the growth model, as well as uncertainty regarding the effects of time of hatching on growth rate. This uncertainty was related to unknown error in the estimation, from statoliths, of age and time of hatching. Broad-scale collaborative studies are recommended, involving exchange of unprocessed and processed statoliths among agers, to evaluate precision and maximize consistency among investigators.

Description: The formation of gas hydrates in gas and oil subsea pipelines often results in blockage and shutdown of these pipelines. Modern control methods depend on understanding the mechanisms through which gas hydrates form. This paper reviews our recent studies of clathrate hydrate formation and inhibition mechanisms using neutron diffraction, differential scanning calorimetry (DSC) and a multiple cell photo-sensing instrument. The structural transformations of water around methane during methane hydrate formation have been studied using neutron diffraction with isotope substitution over the temperature range 4–18 °C and at pressures of 3.4–14.5 MPa. The hydration sphere around methane in the liquid only changes significantly when methane hydrate is formed, with the water shell in the crystalline hydrate being about 1 Å larger than the shell in the liquid. The hydration shell is disordered during methane hydrate formation, with ordering of solvent separated methane molecules occurring only when hydrate has formed. The effects of the addition of three low dosage hydrate inhibitors, PVP, VC-713 and QAB on THF hydrate formation at the surface and in bulk solution have been examined. The QAB inhibitor exhibits the greatest hydrate crystal growth control, while VC-713 is most effective at inhibiting hydrate nucleation. Insight into the perturbations on host and guest molecules due to the presence of these inhibitor molecules has been obtained.

Description: High-resolution seismic profiles (PARASOUND, 4 kHz) of the western Laptev Sea continental margin and the adjacent Vilkitsky Strait were studied in order to gain new evidence about the Weichselian glaciations in Central Siberia and to test reconstructions of maximum ice sheet extents. Four regionally correlatable seismic units, named I (youngest) to IV, were identified in the upper Quaternary sedimentary succession: (I) a thin drape; (II) prograding wedge-shaped deposits along the shelf edge; (III) layered sediments of draping and infilling character with increasing thickness towards the western Laptev Sea shelf edge and the Vilkitsky Strait; (IV) stacked debris-flow deposits. The thin drape of unit I is radiocarbon-dated to Holocene and mainly deposited during the transgression of the Laptev Sea. The wedge-shaped deposits of unit II are interpreted as river deltas, referring to point sources along the shelf edge during the Late Weichselian sea-level lowstand. This indicates that the river input across the Laptev Sea shelf was continuous during marine isotope stage (MIS) 2. The layered sediments of unit III suggest hemipelagic conditions indicative of a sea-level highstand. The pronounced thickening of unit III towards the shelf edge of the western Laptev Sea reflects the lowering of the global sea level during MIS 3. This is associated with increased riverine input due to the northward shift of the Siberian coastline. The stacked debris-flow deposits of unit IV extend continuously from the shelf edge in the Vilkitsky Strait to the continental rise of the western Laptev Sea continental margin. They indicate that large quantities of sediments were deposited directly on the upper continental slope during advances of the Kara Sea ice sheet to the shelf break. These ice-proximal conditions are presumably linked to the Middle Weichselian glaciation (MIS 4). Our evidence confirm earlier reconstructions, suggesting that in central Siberia, the Middle Weichselian glaciation (MIS 4) was of larger extent than the Late Weichselian glaciation (MIS 2).

Description: Dissolution and precipitation rates of brucite (Mg(OHh) were measured at 25°C in a mixed-flow reactor as a function of pH (2.5 to 12). ionic strength (10-4 to 3 M). saturation index (-12 〈 log !1 〈 0.4) and aqueous magnesium concentrations (10-6 to 5 · 10-4 M). Brucite surface charge and isoelectric point (pHrnp) were determined by surface titrations in a limited residence time reactor and electrophoretic measurements. respectively. The pH of zero charge and pHrnP were close to 11. A two-pK. one site surface speciation model which assumes a constant capacitance of the electric double layer (5 F/m2) and lack of dependence on ionic strength predicts the dominance of 〉MgOH2 + species at pH 〈 8 and their progressive replacement by 〉MgOH0 and 〉Mgü- as pH increases to 10-12. Rates are proportional to the square of 〉MgOH2 + surface concentration at pH from 2.5 to 12. In accord with surface speciation predictions. dissolution rates do not depend on ionic strength at pH 6.5 to 11. Brucite dissolution and precipitation rates at close to equilibrium conditions obeyed TST-derived rate laws. At constant saturation indices. brucite precipitation rates were proportional to the square of 〉 MgOH2 + concentration. The following rate equation. consistent with transition state theory. describes brucite dissolution and precipitation kinetics over a wide range of solution composition and chemical affinity: R = k:8 • { 〉 MgOH/}2 • (1 - !12) where k􀂃g is the dissolution rate constant. { 〉i} is surface species concentration (mol/m2). and !1 is the solution saturation index with respect to brucite. Measurements of nonsteady state brucite dissolution rates. in response to cycling the pH from 12 to 2 (pH-jump experiments). indicate the important role of surface hydroxylation - that leads to the formation of Mg oxo or - hydroxo complexes - in the formation of dissolution-active sites. Replacement of water molecules by these oxygen donor complexes in the Mg coordination sphere has a labilizing effect on the dynamics of the remaining water molecules and thus increases reaction rates.

Description: Palmaria mollis or Pacific dulse is used as both a biofilter and feed in temperate, land-based marine aquaculture of abalone and finfish. Land-based tumble-culture techniques capable of producing commercial quantities of P. mollis are still in development. In this study the effects of stocking density, light, salinity, and temperature on growth rates and yields of P. mollis were examined. Under a natural photon flux density (PFD) of 39–52 mol photons m−2 day−1 an aerial stocking density of 3–4 kg m−2 provided highest yields. Specific growth rates of P. mollis were highly correlated with specific light densities (SLD) over a range from 0.0048 to 0.036 mol photons g−1 [fresh wt.] day−1 and no light saturation was evident at a culture temperature of 16±1 °C. Growth of P. mollis was highest at a salinity of 30±1‰, whether municipal tap water or brackish well water was used for diluting seawater. Optimal temperature for growth was 12 °C at low light intensities (SLD=0.010 mol photons g−1 day−1) and 14–18 °C at high light intensities (SLD=0.021 mol photons g−1 day−1). Growth at higher temperatures was positively correlated with increasing light. Lowering culture temperature at night from 15 to 11 °C significantly increased growth for cultures that were not supplied with supplemental inorganic carbon.

Description: The speciation of Cu(II) in marine waters is dominated by organic ligands, which have resisted detailed chemical characterization. In this work we have used immobilized-metal affinity chromatography (IMAC) to isolate Cu(II)-binding ligands from the Chesapeake Bay. We have then used high-performance size-exclusion chromatography (HPSEC) and mass spectrometry (MS) to gather information about the size distributions, molecular weights, and chemical functionality of the ligands isolated by IMAC. Results show that weaker-binding ligands have molecular weights that range from about 230 up to 〉20,000 Da. A portion of these weaker-binding ligands has molecular weight distributions that are consistent with humic substances. The molecular weight distribution of stronger-binding ligands is significantly more narrow with molecular weight values that are less than 1600 Da. Both HPSEC and MS show that the most abundant stronger-binding ligands have molecular weights around 270 Da. Furthermore, mass spectral analysis allows some empirical molecular formulas to be postulated for several ligands. These empirical formulas show that the ligands are abundant in nitrogen, oxygen, and sulfur functionality. In addition, consistency between MS data and data from HPSEC when peptides are used for the calibration combined with the low molecular weights and prevalence of nitrogen, oxygen, and sulfur functionality suggest that the stronger-binding ligands may have been produced directly by organisms in the water. It is not clear at this point, however, the degree to which the molecular information we have gathered represents the majority of the Cu(II)-binding ligands at our sampling site. Nonetheless, combining IMAC, HPSEC, and MS seems to be a promising approach for characterizing Cu(II)-binding ligands in natural waters.

Description: 1-Nitroso-2-naphthol, an excellent color-forming chelating agent, combines to Fe(III), Co(II), Ni(II), Cu(II) and so on to form slightly soluble complexes in aqueous solution. To determine these metal ions, a tedious and time consuming separation technique, such as liquid–liquid extraction, has often been performed. However, these metal-1-nitroso-2-naphthol complexes could be determined conveniently by ultraviolet-visible (UV-Vis) spectrophotometry in Tween 80 micellar medium that has polyoxyethylene groups. After conditions such as pH, the amount of 1-nitroso-2-naphthol and the stability were adjusted to their optimum values, the sensitivities of the metal ions in Tween 80 medium and in chloroform were compared. It was shown that the sensitivities of Fe(III) and Co(II) in Tween 80 medium were higher than in chloroform, but that of Cu(II) was lower. The interfering effects among analytes ions, Fe(III), Co(II), Ni(II) and Cu(II) were more serious than by other ions, but the interfering effects could be removed by adjusting pH or adding the masking agents such as NH3 or oxalate. Detection limits of Fe(III), Co(II), Ni(II), and Cu(II) were 0.024, 0.016, 0.039 and 0.023 μg ml−1, respectively, and the correlation coefficients of these calibration curves were above 0.996. Recovery yields of the metal ions in the mixed standard solution ranged from 96 to 103%, and their coefficients of variation were low ranging between 0.94 and 1.75%. Cu(II) in brass sample and the amount of Fe(III) in steel sample were also determined. This proposed technique is simple, convenient and speedy.

Description: Analysis of three recent diagenetic model codes (OMEXDIA, CANDI and STEADYSED) revealed that codes have a rigid, static and problem-specific character, leaving little autonomy for the application user. The resulting lack of flexibility and extensibility, and the associated need for ground-level reprogramming, constitutes a major barrier for potential model users. Present codes have apparently passed a critical threshold of code complexity, above which code development becomes time-consuming and expensive using the present procedure-oriented techniques. We have explored the advantages of object-oriented technology and the concept of a problem-solving environment to improve the quality of software for reactive transport modelling. A general blueprint for an object-oriented code for modelling early diagenesis is presented. The MEDIA environment consists of a toolbox of building blocks (element, species and process objects), which can be combined freely by the user to construct new models (without the need for recompilation). An object-oriented database stores current objects and accommodates new user-defined building blocks. Altogether, it is advocated that by improving the software quality, one can substantially lower the threshold for using model codes as an integrated data-analysis tool.

Description: The MEDIA (Modelling Early DIAgenesis) software package comprises a flexible and extensible software system that provides problem-solving assistance for simulating 1D reactive transport in surface sediments. MEDIA allows multiple diagenetic models to be built by extending a model template with new model components from a toolbox of available objects (elements, species, parameters, reactions). A detailed review is given of the transport and reaction components available for model construction. Upon assemblage, the model is channelled to the numerical subunit of the MEDIA package. Via a canonical transformation, the user-defined mixed kinetic-equilibrium model is rearranged into a proper set of differential algebraic equations (DAE), for which both steady state and transient solutions can be calculated. Steady-state profiles are obtained either directly using a Newton–Raphson method, or alternatively, as the asymptotic result of a dynamic simulation. Dynamic simulations involve a global implicit procedure based on the stiff-ODE solver package VODE, employing a direct substitution approach to reduce the number of equations in the DAE system. Verification of the MEDIA code was accomplished (1) by comparison with analytic models and (2) by emulating the model formulation and output of the existing diagenetic model code STEADYSED. As an example application, a diagenetic model was constructed to analyse an extensive dataset collected from a marine sediment in the Santa Barbara Basin (California). The different pathways of organic matter mineralization were modelled, and the coupling among the biogeochemical cycles of C, O, N, S, Mn and Fe was investigated. Depth profiles of both porewater and solid-phase constituents could be reproduced with great accuracy.

Description: A hydrate state-of-the-art is given for fundamental measurements and modeling of phase equilibria and kinetics, via a 204 paper summary of the triennial International Hydrate Conference in May 2002. Emphasis is given to new measurement techniques with their application in the next generation of hydrate modeling. Future challenges are presented. With this Phase Equilibria Plenary Lecture in the 17th International Conference on Chemical Thermodynamics, goes my appreciation for both the honor, and the motivation to attempt a state-of-the-art summary. All too frequently such summaries take on a personal perspective that omit important developments, perhaps because they were not developed by the writer, and were therefore less familiar. Yet currently we are two months after the fourth triennial International Conferences on Gas Hydrates (Yokohama, Japan, 19–23 May 2002). That conference was blessed with a chairman who provided two volumes (1062 pages) written by 500 (even!) authors. A CD of conference papers is available at nominal cost through the ICGH-4 Secretariat (icgh@mori.mech.keio.ac.jp). The challenge of this invited manuscript is to provide a pure and applied phase equilibria summary of the above conference, supplemented by a few other references, in an overview of the hydrate community’s current direction. The conference provides a technical snapshot of hydrate research over the world, making it possible to weave a few current threads into the hydrate fabric in space and time. Emerging images provide some clues to the future. To supplement this view the reader may wish to turn to the other reviews [1], [2], [3], [4], [5], [6] on pure and applied phase equilibria of hydrates.

Description: As a part of the Russian-German project "Siberian River-Runoff (SIRRO)" the major element composition of the dissolved load and the major and trace element composition of particulate load and bottom sediment of the Yenisei River and Estuary were analyzed and examined in context of the basin lithology and climate. In addition, the processes controlling the transformation of the river load in the estuarine mixing zone were investigated. The chemical composition of the dissolved and particulate load of the Yenisei fluvial endmember is generally comparable to that of other major world rivers. The dissolved load is chiefly controlled by carbonate weathering and the chemical composition of the river suspended particulate matter (SPM) is similar to that of the North American Shale Composite (NASC), which represents the weathering product of the upper continental crust. The Chemical Index of Alteration (CIA) of the Yenisei SPM amounts to 71, which indicates moderate chemical weathering. With regard to the SPM geochemistry, the Yenisei occupies an intermediate position between the adjacent rivers Khatanga and the Lena. Drastic changes in the composition of the river load are seen in the mixing zone between fresh and salt water. While dissolved Na, Ca, Mg, K, CI, S04, F, Br, Sr and HC03 behave conservatively, dissolved Fe is completely removed from solution at very low salinities. Particulate Mn exhibits a pronounced mid-salinity minimum concomitant with a maximum of dissolved Mn, which is probably related to suboxic conditions in the area of the so-called "marginal filter", where highest turbidities are found. The Mn-minimum in SPM is paralleled by depletions of the elements Ba, Zn, Cd, Ni, Cu and V, which can be associated with manganese particles. The estuarine bottom sediments are composed of mud and sand and the sedimentological parameters of the bottom sediments have to be considered for the interpretation of the bulk geochemical data. The chemical composition of the mud is comparable to the SPM, whereas the sand is relatively enriched in Si/Al, Ba/Al, Zr/Al and Sr/Al ratios and depleted in transition metals.

Description: An idealized numerical model of the tropical Atlantic Ocean is used to study the structure, energetics and heat flux of the Atlantic tropical instability waves (TIWs). The model results compare well with the observations, and they both show that, unlike commonly assumed, the TIWs in the Atlantic exist on both sides of the equator and are generated not only in the summer but from May to January. Furthermore it is demonstrated that the Atlantic TIWs are generated by barotropic instability of the shear between the equatorial undercurrent and the northern south equatorial current and make a surprisingly small contribution to the heat budget of the equatorial mixed layer. The model results reveal that the often published strong meridional heat flux divergence of the TIWs is largely compensated for by their vertical heat flux divergence.

Description: The Samoan volcanic lineament has many features that are consistent with a plume-driven hotspot model, including the currently active submarine volcano Vailulu'u that anchors the eastern extremity. Proximity to the northern end of the Tonga trench, and the presence of voluminous young volcanism on what should be the oldest (∼5 my) western island (Savai'i) has induced controversy regarding a simple plume/hotspot model. In an effort to further constrain this debate, we have carried out geochronological, geochemical and isotopic studies of dredge basalts from four seamounts and submarine banks that extend the Samoan lineament 1300 km further west from Savai'i. 40Ar/39Ar plateau ages from Combe and Alexa Banks (11.1 my—940 km, and 23.4 my—1690 km from Vailulu'u, respectively) fit a Pacific age progression very well. The oldest volcanism (9.8 my) on Lalla Rookh (725 km from Vailulu'u) also fits this age progression, but a new age is much younger (1.6 my). Isotopically, these three seamounts, along with Pasco Bank (590 km from Vailulu'u), all lie within, or closely along extensions of, the Sr–Nd–Pb fields for shield basalts from the Eastern Samoan Province (Savai'i to Vailulu'u); this clearly establishes a Samoan pedigree for this western extension of the Samoan hotspot chain, and pushes the inception of Samoan volcanism back to at least 23 my. From geodetic reconstructions of the Fiji–Tonga–Samoa region, we show that the northern terminus of the Tonga arc was too far west of the Samoa hotspot up until 1–2 my ago to have been a factor in its volcanism. Young rejuvenated volcanism on Lalla Rookh and Savai'i may be related to the rapid eastward encroachment of the Trench corner. The Vitiaz Lineament, previously thought to mark a proto-Tongan subduction zone, was more likely created by the eastward propagation of the tear in the Pacific Plate at the northern end of the arc.

Description: Two new compounds isolated from an extract of a Central Asian lichen [Umbilicaria proboscidea (L.) Schrader=Syn.: Gyrophora proboscidea (L.) Ach.] are glucosides with mono- and di-prenylated xanthones as the aglycones and a saccharide moiety from two glucoses linked at C-7. The structures were elucidated on the basis of extensive spectroscopic analysis (1D and 2D NMR, MS, IR and UV) and by hydrolysis. Two new compounds (1, 2) isolated from an extract of a Central Asian lichen [Umbilicaria proboscidea (L.)] Schrader are glucosides with mono- and di-prenylated xanthones as the aglycones and a saccharide moiety from two glucoses linked at C-7. The structures were elucidated on the basis of extensive spectroscopic analysis (1D and 2D NMR, MS, IR and UV) and by hydrolysis.

Description: Gauss–Seidel is often the smoother of choice within multigrid applications. In the context of unstructured meshes, however, maintaining good parallel efficiency is difficult with multiplicative iterative methods such as Gauss–Seidel. This leads us to consider alternative smoothers. We discuss the computational advantages of polynomial smoothers within parallel multigrid algorithms for positive definite symmetric systems. Two particular polynomials are considered: Chebyshev and a multilevel specific polynomial. The advantages of polynomial smoothing over traditional smoothers such as Gauss–Seidel are illustrated on several applications: Poisson’s equation, thin-body elasticity, and eddy current approximations to Maxwell’s equations. While parallelizing the Gauss–Seidel method typically involves a compromise between a scalable convergence rate and maintaining high flop rates, polynomial smoothers achieve parallel scalable multigrid convergence rates without sacrificing flop rates. We show that, although parallel computers are the main motivation, polynomial smoothers are often surprisingly competitive with Gauss–Seidel smoothers on serial machines.

Description: The accurate dating of fossil coral reefs is of prime importance in determining the timing of deglaciation events and thus understanding the mechanisms driving glacial–interglacial cycles. So far, the most useful coral reef records of past sea level changes are those related to the last deglaciation and the Last Interglacial period. U/Th ages for older isotopic stages are more limited, due to the scarcity of datable material, reflecting diagenetic alteration. Most data are from emergent parts of reefs and reef terraces in active subduction zones where relative sea level records may be biased by variations in rates of tectonic uplift. New constraints on sea level changes over the past 300 000 yr are based on high-precision U-series age measurements of successive reef units on Mururoa. These have been cored in four continuous 300-m-long drill holes with seaward inclinations of 30 to 45° on the northeastern rim of the atoll. Past sea level positions have been calculated from the radiometric ages of corals by correcting the present depth of subsurface horizons both for thermal subsidence and for depositional palaeodepth. The location of this atoll at a considerable distance from former ice sheets (‘far field’) minimises the influence of glacio–isostatic rebound. Prominent units formed during four periods of relative sea level highstands, including the Holocene and stages 5 (∼125 ka), 7 (∼212 ka) and 9 (∼332 ka). These are primarily composed of coralgal frameworks that grew in very shallow water. Three periods of relative low stand correspond to stages 2 (∼17–23 ka), 4 (∼60 ka) and 8 (∼270 ka) during which small reefs developed in association with large bioclastic accumulations. Good agreement with the timing of sea level changes based on oxygen isotope measurements in deep-sea cores is noted for most of the dated reef units. We report here the first accurate coral record of the Last Glacial Maximum in the Pacific, 135–143 m below the present sea surface, suggesting that sea level may have been lower than expected during this period.

Description: Climate variability in the northeast Atlantic was investigated on glacial–interglacial and millennial time scales during the last 200 000 years, using sea surface temperature (SST) records derived from planktonic foraminiferal diversities and from Mg/Ca measurements on Globigerina bulloides. Paleoceanographical interpretations are supported by species composition analyses, benthic and planktonic isotopic data as well as records of iceberg-rafted debris (IRD). Differences of climate development are recognized for both interglacial and glacial periods. Temperature estimates indicate slightly warmer conditions (up to 2°C) during marine oxygen isotope stage (MIS) 5e than during the Holocene. In contrast to the last glaciation, when the SST minimum coincided with a minimum in solar insolation immediately before Termination I, during the penultimate glaciation a long SST minimum occurred at times of intermediate solar insolation well preceding the onset of Termination II. This discrepancy between two glacial terminations may be explained by an inherently different orbital configuration characteristic for each glacial interval. Despite these differences between the two glacial trends, the superimposed shorter-lived climatic events reveal the same order of principal steps, implying their common causal nature. A direct comparison of faunal SSTs with those retrieved from Mg/Ca analysis shows that Mg/Ca-derived temperatures follow the general glacial–interglacial trend; however, the latter appear to be largely overestimated. Supported by δ18O data in G. bulloides, which show little response to millennial-scale variability, there seems to be a need for species-dependent calibration experiments that also consider the different oceanographic settings this particular species can live in.

Description: Two sediment cores from the northern North Atlantic, one from the Iceland Plateau and one from the Rockall Plateau, were investigated in order to examine the response of deep-sea benthic ostracodes to climate-related environmental changes since marine isotope stage (MIS) 7. Ostracode fauna was divided into three factor assemblages by using Q-mode factor analyses and diversity was calculated using the Shannon–Wiener index. The Iceland Plateau revealed an ‘interglacial assemblage’ dominated by Henryhowella, a transitional assemblage dominated by Eucythere, and a ‘background assemblage’ that consists of the common taxa Krithe and Cytheropteron. The presence of Henryhowella is linked to conditions that prevailed during the peak interglacial periods (MIS 5e and 1), characterized by increased food supply, well-oxygenated bottom water, and lateral advection. The presence of Eucythere, mainly during the interstadial periods, appears to be related to slightly increased food supply, whereas the ‘background assemblage’ is considered to be opportunistic and able to cope with decreased food supply as interpreted for glacial times. On the Rockall Plateau the opportunistic ‘background assemblage’ (consisting mainly of Krithe, Argilloecia, and Cytheropteron) shows no obvious relation to climate changes. The ‘interglacial assemblage’ consists of several taxa dominated by Pelecocythere but, as on the Iceland Plateau, it also contains Henryhowella. The third assemblage is the ‘glacial assemblage’ that consists of a variety of taxa, several of which are known from the modern Arctic Ocean and the Greenland Sea shelf. Thus, this assemblage indicates glacial conditions on the Rockall Plateau that are comparable to those found in the present-day Arctic Ocean. Diversity calculations revealed higher ostracode diversities in glacial than in interglacial episodes in both cores and particularly high diversities during periods of increased input of iceberg-rafted debris (IRD) in the Rockall Plateau core. Both cores reveal lower surface-water productivity during the glacial compared to the interglacial periods and particularly low productivity during the IRD events, as inferred from carbonate contents. We assume, therefore, that ostracode diversity in the study areas is negatively correlated with food flux.

Description: Bolboform distribution in space and time is analysed from a circum-Antarctic belt of lower Eocene to uppermost Miocene sediments from the Southwest Pacific, Southeast Pacific (Bellinghausen Basin), Maud Rise and South Atlantic, and Indian Ocean (Kerguelen Plateau) regions. A correlation panel using established Cenozoic planktic foraminiferal and calcareous nannofossil zones is linked to the Bolboforma zonation scheme for the Southern Ocean. Evolution of surface watermasses and their boundaries, the major oceanic fronts, are tracked using the microfossil distributions and general sediment characteristics, and are in turn linked to the Bolboforma distribution. Specifically, the migration of both the Antarctic Polar Front and the Subtropical Front northwards from continental Antarctica, starting in the earliest Oligocene and culminating in the late Miocene establishment of ‘modern’ conditions, links the bolboforms in the Southern Ocean with subantarctic watermass conditions between the equivalent of today’s Subantarctic and Subtropical fronts. The occurrence of bolboforms in sediments including subtropical microfossil assemblages from north of the Subtropical Front, as in the Tasman Sea, is anomalous. We suggest that they were transported into this region by subsurface (intermediate depth) waters generated by subduction of subantarctic surface water at southern oceanic fronts. The distribution of bolboforms more widely outside the Southern Ocean may define the pathways of Southern Component Intermediate Water (Antarctic Intermediate Water) during the Tertiary, and may account for their bipolar distribution. Bolboforms exhibit a circum-Antarctic distribution prior to the development of a full circum-Antarctic circulation system following the opening of the Tasmanian and Drake gateways. It is inferred that a West Antarctic Seaway between the Ross Sea and Weddell Sea embayments may have afforded oceanic connection between the Southwest Pacific and the southern Atlantic during the Eocene–Oligocene, facilitating dispersal and such a distribution.

Description: Living and dead benthic foraminiferal assemblages from two size fractions, 63–250 μm and 〉250 μm, were studied at 128 stations from the shelves down to abyssal plains of the Gulf of Guinea in the eastern equatorial Atlantic. The sample size ranged between 300 and 400 cm2 of the sediment/water interface, with a penetration depth of 1 cm. Environmental parameters were quantified for sediment composition, food webs, bottom-water oxygen concentrations, and benthic oxygen respiration. Seven major station groupings (named G1–G7) are subdivided by factor analysis. The three most abundant species therein are discussed with respect to their ecological requirements, for both size classes and for living and dead counts. For 49 living species, the range of environmental gradients is established, and for five species live observations are reported. Five station groupings can be attributed toward stepwise ranges scaled by bathymetry and flux rates of organic carbon (G4, 27–75 m; G5, 68–269 m; G6, 250–740 m; G2, 674–2007 m; G1, 1475–4970 m). Two geographically restricted station groupings locally interfinger with other groupings in the upper bathyal and abyssal water depths (G7, 82–451 m; G3, 1002–4658 m). G7 shows lowered oxygen concentrations and benthic oxygen respirations, whereas hemipelagic sediments are typical of G3. The interfingering of G7 and G3, however, is not purely a result of the increasing number of species most perfectly adapted to these environments but rather that these groupings are structured by the decrease of species with lower tolerance towards environmental perturbation. In fact, the more common species have an environmental range much broader than the environmental frame of the groupings they dominate. This observation holds for all size classes and for live and dead counts. We conclude that species-specific preferences and thresholds provide a more valuable and more consistent tool in environmental research than the environmental ranges observed for assemblages.

Description: The nature of rhythmic carbonate-rich successions such as limestone^marl alternations has been, and still is, subject to controversy. The possibility of an entirely diagenetic origin for the rhythmic calcareous alternations is discarded by most authors. One problem with an entirely diagenetic, self-organized development of limestone^marl alternations is the fact that limestone and marl beds in many examples are laterally continuous over hundreds of meters or even kilometers. In an entirely self-organized system, lateral coupling would be very limited; thus one would expect that, rather than laterally continuous beds, randomly distributed elongate nodules would form. We address the origin of limestone^marl alternations using a computer model that simulates differential diagenesis of rhythmic calcareous successions. The setup uses a cellular automaton model to test whether laterally extensive, rhythmic calcareous alternations could develop from homogeneous sediments in a process of self-organization. Our model is a strong simplification of early diagenesis in fine-grained, partly calcareous sediments. It includes the relevant key mechanisms to the question whether an external trigger is required in order to obtain laterally extensive limestone^ marl alternations. Our model shows that diagenetic self-organization alone is not sufficient to produce laterally extensive, correlatable beds. Although an external control on bedding formation could be considered to have solved the problem as commonly assumed, we here suggest an interesting third possibility: the rhythmic alternations were formed through the interaction of both an external trigger and diagenetic self-organization. In particular we observe that a very limited external trigger, either in time or amplitude, readily forms correlatable beds in our otherwise diagenetic model. Remarkably, the resulting rhythmites often do not mirror the external trigger in a one-to-one fashion and may differ in phase, frequency and number of couplets. Therefore, the interpretation of calcareous rhythmites as a one-to-one archive of climate fluctuations may be misleading. Parameters independent of diagenetic alteration should be considered for unequivocal interpretation.

Description: The response of coccolithophore assemblages to short-term millennial and centennial climatic changes over the last 50 kyr is studied in core M39029-7 from the Gulf of Cadiz (Atlantic Ocean) and core MD95-2043 from the Alboran Sea (Western Mediterranean Sea). The nannoplankton data are compared with oxygen isotopes, U37k′-SST and other biogeochemical and sedimentological proxies to obtain a new perspective of the paleoceanography and paleoecology of the area during these short-term climatic changes. Coccolithophores indicate that Heinrich events (HE) were characterised by the presence of cold, low salinity and turbid water masses on both sides of the Strait of Gibraltar. High abundances of the Lower Photic Zone (LPZ) species Florisphaera profunda in the Gulf of Cadiz synchronous with HE are interpreted as being an evidence of upper water-column stratification on the Atlantic side. These episodes coincided with input of terrigenous material, especially during H2. Surface waters during Dansgaard-Oeschger (DO) Stadials were also cold and turbid, while most of DO Interstadials were characterised by warm-water flora. The increase in small placoliths (small Gephyrocapsa and Emiliania huxleyi (〈4 μm)) reveals a higher coccolithophore production during DO Interstadials and the Holocene. Conversely, HE and most of DO Stadials show peaks of E. huxleyi (〉4 μm), which is considered here as a cold-water indicator. The sharp decrease in large specimens of E. huxleyi related to the warming trend in the last deglaciation can be used as a biostratigraphic reference level that marks—at least approximately—the deglaciation and the beginning of the Holocene. Peaks of F. profunda are observed during Termination 1 (T1) in the Alboran Sea. They are isochronous with the “Organic-Rich Layer 1” recognised in the Western Mediterranean. In this interval, the water column of the region was stratified as a consequence of the global increase in the sea level following the deglaciation. Quantitative analyses of the coccolithophore assemblage allow us to interpret that coccolithophore production has been higher in the Alboran Sea than in the Gulf of Cadiz during the Holocene.

Description: Records of benthic foraminiferal assemblage variations and benthic δ13C along 12 sediment cores from the western Iberian Margin, between 36° and 42°N at water depths from 820 to 3580 m, are used to monitor fluctuations of the Mediterranean Outflow Water (MOW) during the past 30 ka. The chronostratigraphy of the cores is based on planktonic δ18O records, 14C AMS-dating, and the recognition of Heinrich Events H1 through H4. Increased abundances of suspension feeding benthic foraminifers, denoted as ’Epibenthos Group‘, closely match areas where the recent MOW core layers impinge on the continental slope at 800 and 1300 m water depth, and near-bottom current velocities are enhanced. Elevated ‘Epibenthos Group’ abundances, increased benthic δ13C, and sedimentological evidence for winnowing and erosion are found in glacial sections up to the earliest Termination I in cores at water depths between 1600 and 2200 m off southern Portugal. The combined evidence reveals enhanced current activity at these depths due to a deep glacial MOW. The MOW advection at the Portuguese margin during the last Glacial was about 700 m deeper than today, conceivably forced by increased MOW density due to higher salinity and colder temperatures of Mediterranean waters. The deep MOW current gradually decreased in strength and shoaled to 1300 m water depth during the Termination and early Holocene. A shallow MOW core layer became active with the onset of Termination I at depths between 600 and 1000 m. Both the shallow and deep MOW current culminated during the Younger Dryas period. The present flow pattern with two MOW core layers centred at 800 and 1300 m water depth was established between 7.5 and 5.5 ka.

Description: A synopsis of results from two sediment trap moorings deployed at the mid- and outer slope (water depths 1450 and 3660 m, respectively) of the Goban Spur (N.E. Atlantic Margin) is presented. Fluxes increase with trap deployment depth; below 1000 m resuspended and advected material contributes increasingly to bulk flux. Fluxes of dry weight, POC and diatoms in the traps 400 m above bottom (mab) are smaller than those recorded at the sediment surface due to lateral fluxes in the benthic nepheloid layer. These near-bottom fluxes are larger at shallower water depths. 231Pa/230Th ratios in sedimenting material suggest that boundary scavenging is not significant at the Goban Spur. Fluxes of 210Pb in the intermediate and deep traps are comparable to the 210Pb supply rate at this site. At the outer slope, sediment 210Pb fluxes are similar to those measured in the traps 400 mab; at the mid-slope they are a factor of 2 higher, once again indicating large near-bottom lateral particle input. Based on POC-normalised biomarkers in sedimenting material, we followed changes in the quality of sedimenting material with differing trap depth and on seasonal and event-related time scales. In spring fresh, diatom-dominated sedimentation occurs, with progressive degradation of POC with time (to winter) and depth (from 600 to 3220 m). Deeper traps are distinguished on the basis of opal and aluminium fluxes that are dominant in lateral input. A storm event during late September 1993 was clearly reflected in the δ15N isotope ratio of sedimenting material, with a time lag of 2–3 weeks. Diatom and opal fluxes were elevated in this storm-related signal, and its biomarker composition in the 600-m trap was similar to that during spring. An estimate made of upward nitrate flux (new production) at the shelf break and at the outer slope indicated a 2-fold higher new (export) production at the shelf break. Particulate organic carbon export from the shelf break to below the depth of maximal seasonal mixing ranges between 3 and 9% of primary production.

Description: In September 1993 (M26) and June/July 1996 (M36), a total of 239 surface samples (7 m depth) were collected on two transects across the open Atlantic Ocean (224 samples) and northwest European shelf edge area. We present an overview of the horizontal variability of dissolved Cd, Co, Zn, and Pb in between the northwest and northeast Atlantic Ocean in relation to salinity and the nutrients. Our data show a preferential incorporation of Cd relative to P in the particulate material of the surface ocean when related to previously published parallel measurements on suspended particulate matter from the same cruise. There is a good agreement with results recently estimated from a model by Elderfield and Rickaby (Nature 405 (2000) 305), who predict for the North Atlantic Ocean a best fit for αCd/P=[Cd/P]POM/[Cd/P]SW of 2.5, whereas the approach of our transect shows a αCd/P value of 2.6. The Co concentrations of our transects varied from 〈5 to 131 pmol kg−1, with the lowest values in the subtropical gyre. There were pronounced elevations in the low-salinity ranges of the northwest Atlantic and towards the European shelf. The Co data are decoupled from the Mn distribution and support the hypothesis of marginal inputs as the dominant source. Zinc varied from a minimum of 〈0.07 nmol kg−1 to a maximum of 1.2 and 4.8 nmol kg−1 in regions influenced by Labrador shelf or European coastal waters, respectively. In subtropical and northeast Atlantic waters, the average Zn concentration was 0.16 nmol kg−1. Zinc concentrations at nearly three quarters of the stations between 40°N and 60°N were 〈0.1 nmol kg−1. This suggests that biological factors control Zn concentrations in large areas of the North Atlantic surface waters. The Pb data indicated that significant differences in concentration between the northwest and northeast Atlantic surface waters presently (1996) do not exist for this metal. The transects in 1993 and 1996 exhibited Pb concentrations in the northeast Atlantic surface waters of 30 to 40 pmol kg−1, about a fifth to a quarter of the concentrations observed in 1981. This decline is supported by our particle flux measurements in deep waters of the same region.

Description: During the Thetis-2/MAST-2 tomography experiment, T7-XBT calibrated (accuracy ∼0.05°C) probes were launched ∼28 km apart between France and Algeria, twice a month from Feb. to Sep. 1994. Combined with infrared images, altimetric data and ship drifts, they provide definite information on the structure, drift and role of the eddy-like mesoscale phenomena generated by the Algerian Current instability. When embedded in this alongslope current, these phenomena generally propagate downstream at a few km/day and are markedly asymmetrical. Because of the topography in the eastern part of the Algerian Basin, they separate from the current, become more symmetrical and follow an anticlockwise circuit in the open basin. These phenomena are deeper than ∼750 m and entrain seaward pieces of the Levantine Intermediate Water (LIW) vein flowing along the Sardinian slope, thus being responsible of the large spatial and temporal variability of the LIW distribution in the open basin. The non-existence of a LIW vein flowing westward across the Algerian Basin is definitely demonstrated. In the Gulf of Lions, new insights are provided into the formation and spreading of the Winter Intermediate Water (WIW), which is the WesternMediterranean counterpart of LIW. Considering the large amount of WIW formed during this mild winter, it is clear that this water has not received enough attention yet, and is certainly a major component of the Mediterranean outflow at Gibraltar. Finally, the XBT data account for the eastward flow of the WesternMediterranean Deep Water (WMDW) off Algeria.

Description: As part of the OMEX I project, nutrient determinations were made on 17 cruises in the region of the Goban Spur and La Chapelle Bank between 46 and 51°N, in all seasons of the year, between 1993–1995. Over this period no change was detectable in the structure of the water masses below the deep winter mixed layer. The N : P (dissolved nitrate-to-phosphate) ratio changed from 16 at 100-m depth to less than 15 at 3300-m depth. At intermediate depths nutrient and oxygen data indicate the presence of Mediterranean Outflow water overlying Labrador Sea Water at its most eastern extension. Estimated maximum levels of production in the spring bloom are the total N-limited new primary production equivalent between 24 and 41 gC m−2, the equivalent maximum diatom production is 11 gC m−2. Measurements during the spring bloom suggest a conversion factor of 1 μM nitrate to 1 μg l−1 chlorophyll, at the shelf break, which is consistent with other recent measurements in European shelf seawaters. Sediment trap data suggest that 80% (5.4 g m−2) of the opal produced in the spring bloom dissolved before reaching the sediment trap at 600 m. A comparison of the winter and summer profiles for dissolved silicon suggests a similar dissolution of 9±3 g opal m−2 above 300-m depth. Measurements of dissolved organic carbon (DOC) in September 1994 show an enrichment of 7 μM-C above the seasonal thermocline relative to the winter values (52±4 μM). In winter dissolved organic nitrogen represents 40% of the pool of total dissolved nitrogen. There is no consistent evidence of an increase in the concentration of DON during summer. Measurements of nitrate in surface waters in January 1994 show that concentrations off-shelf vary with the temperature of the water and are related to the depth of winter mixing. Mixing in surface waters is discontinuous at the shelf break, demonstrating the degree to which exchange across the shelf break is limited even in winter. OMEX winter measurements of nitrate concentrations can be used to estimate the flow of water across the shelf break that would be required to maintain the nitrogen balance in the North Sea at a steady state. The estimate is 0.6 Sv (1 Sv=106 m3 s−1), which is similar to an earlier estimate of a total flow of 1.7 Sv based on salt budgets (cf. Huthnance, Deutsche Hydrographische Zeitschrift, 49 (1997) 153).

Description: Recent trawling in the Southern Ocean has yielded an unusual and relatively large collection of deep-sea octopods, comprising four species in two genera. Several deep-sea genera, which are inadequately characterised, have been reported previously from the Southern Ocean. Within this paper, all the relevant historical type material has been examined and a full revision has been undertaken. Species previously considered to be representative of the genus Bentheledone have either been moved to Thaumeledone or are considered nomen dubium. A revised diagnosis of Thaumeledone is provided together with redescriptions of its Southern Ocean species as well as a description of a new species. A new genus has been erected to accommodate the remainder of the new specimens.

Description: Redfield stoichiometry has proved a robust paradigm for the understanding of biological production and export in the ocean on a long-term and a large-scale basis. However, deviations of carbon and nitrogen uptake ratios from the Redfield ratio have been reported. A comprehensive data set including all carbon and nitrogen pools relevant to biological production in the surface ocean (DIC, DIN, DOC, DON, POC, PON) was used to calculate seasonal new production based on carbon and nitrogen uptake in summer along 20°W in the northeast Atlantic Ocean. The 20°W transect between 30 and 60°N covers different trophic states and seasonal stages of the productive surface layer, including early bloom, bloom, post-bloom and non-bloom situations. The spatial pattern has elements of a seasonal progression. We also calculated exported production, i.e., that part of seasonal new production not accumulated in particulate and dissolved pools, again separately for carbon and nitrogen. The pairs of estimates of `seasonal new production’ and `exported production’ allowed us to calculate the C : N ratios of these quantities. While suspended particulate matter in the mixed layer largely conforms to Redfield stoichiometry, marked deviations were observed in carbon and nitrogen uptake and export with progressing season or nutrient depletion. The spring system was characterized by nitrogen overconsumption and the oligotrophic summer system by a marked carbon overconsumption. The C : N ratios of seasonal new as well as exported production increase from early bloom values of 5–6 to values of 10–16 in the post-bloom/oligotrophic system. The summertime accumulation of nitrogen-poor dissolved organic matter can explain only part of this shift.