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: Major- and trace-element as well as Pb-isotope data are presented for greenschist- to amphibolite-facies greenstones from two locations: (1) metabasalt-breccias from the Galfipagos Rift at 100°W; and (2) metabasalt-breccias and unbrecciated greenstones from the Chile Ridge at 38°S. Greenstone-breccias from both locations display stockwork-like sulfide mineralizations related to the upflow portion of a hydrothermal convection system. Whereas Galfipagos Rift stockwork sulfides belong to the "normal" type containing Cu-Fe-sulfides, Chile Ridge stockwork sulfides are galena-rich Pb-Zn _ Cu-sulfides and represent a previously unknown type of sulfide mineralisation in a MORB environment. Geochemically, the greenstones can be divided into two types: (1) The unbrecciated galena-free greenstones from both Chile Ridge and Galfipagos Rift show at least a 10-20-fold Pb enrichment compared to fresh MORB. With respect to similar Pb enrichment measured in greenstones from two other locations, i.e. DSDP Hole 504B and Galfipagos Rift near 86°W, we suggest that this may be a general feature of all stockwork-mineralised oceanic greenstones. (2) The galena- and quartz-rich metabasalt-breccias from the Chile Ridge are up to 3000-fold enriched in Pb (up to 1000 Ixg/g Pb in the whole-rock analyses) compared to MORB and indicate Pb mineralisation two orders of magnitude higher than that of the "normal" greenstone-type. A mass-balance calculation carried out using crustal column thickness of 3000 m with a 200-m-thick greenstone layer and 0.15 m of galena-beating breccias shows that at the Chile Ridge ~ 42% of the entire Pb is concentrated in the greenstones. This suggests that the rest of the crustal column is depleted in 58% of its primary Pb content. This degree of depletion matches well with previous calculations that a 56% depletion of Pb in oceanic crust subjected to mantle-recycling via subduction would be necessary to yield a HIMU mantle source within 2 Ga. Despite the need for future investigations into the extent and volume of the Pb enrichment in Chile Ridge greenstones, we believe that this process of major Pb redistribution is capable of creating huge volumes of oceanic crust that on average are extremely Pb-depleted and which when recycled would produce the HIMU source. Keywords: Chile Ridge; Galfipagos Ridge; Hydrothermal alteration; Greenstones; Geochemistry; Mineralogy

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: In situ stress and pore pressure data from the Valhall and Ekofisk oil reservoirs indicate that at the onset of production in both fields an incipient state of normal faulting existed in the crest of the anticlinal structures. In contrast, on the flanks of the structures the initial least principal stress values indicate an almost isotropic state of stress. Oil production from both fields caused marked pore pressure reductions as well as poroelastic reductions of the least principal stress in both the crest and flanks of the two structures. We demonstrate that as a result of production-induced pore pressure and stress changes, normal faulting appears to have spread out from the crests of the structures on to the flanks. Further evidence of a normal faulting stress state at Valhall has been found using data from a passive seismic monitoring experiment. Numerous microearthquakes were recorded during a six week monitoring period that are located at the very top of the reservoir or in the shale caprock immediately above it. An inverse/composite focal plane mechanism of these microearthquakes is consistent with a normal faulting stress regime.

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: A standard, universally useful classification scheme for deepwater habitats needs to be established so that descriptions of these habitats can be accurately and efficiently applied among scientific disciplines. In recent years many marine benthic habitats in deep water have been described using geophysical and biological data. These descriptions can vary from one investigator to another, which makes it difficult to compare habitats and associated biological assemblages among geographic regions. Using geophysical data collected with a variety of remote sensor systems and in situ biological and geologic observations, we have constructed a classification scheme that can be used in describing marine benthic habitats in deep water.

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: A structural model encompassing the southern North Sea basin west of the Central Graben has been developed. This model consists of a rift system affecting the post-salt section around the basin margin and a large area of detached compressional buckle folds within the basin. This pattern is initially a response to gravity sliding of the post-salt section on the salt within the basin during the late Triassic to late Jurassic. A close relationship between the location and trend of the peripheral graben system and basement structures in the pre-salt is noted. Pre-Jurassic extension across the peripheral graben systems was balanced by the sum of fault heaves at the pre-salt (Rotliegend) level and shortening across salt-cored buckle folds in the post-salt section. Salt pillows and swells passively infilled the cores of these gravity-induced buckle folds. Cretaceous and Tertiary inversion involved basin tilt and renewed movement on basin-bounding basement faults; notably, reverse movements did not propagate from basement structures up into the peripheral graben systems. The post-salt sedimentary section experienced gravity spreading in response to inversion-related uplift, resulting in syn-inversion extensional faulting in the Sole Pit High, where the Mesozoic section was thickest. This extension, combined with a loss of fault heave in the pre-salt section, was balanced by amplification of salt-cored buckle folds in the centre of the basin. In the context of the model described here, salt pillows represent passive infill of thin-skinned, compressional buckle folds which later amplified during thick-skinned basement shortening. Crestal collapse of such folds occurs via normal faulting, accompanied by reactive diapirism. Such reactive diapirs establish conduits through which salt may leak, leading to pillow deflation and ultimately conduit preservation as a salt wall (flanked by rim synclines in areas where the buckle folds were emergent). The salt structures described here are related to cover folds and faults, which in turn reflect episodes of basin extension, tilting and inversion. Hence individual salt structures can be said to be only remotely connected with regional, intraplate stresses.

Description: Normal faulting and halokinesis have been important controls on the deposition and subsequent deformation of Mesozoic and Tertiary strata in the North Sea. In addition to the previously documented mechanisms of salt withdrawal, dissolution and differential sedimentary loading, it is recognized that gravity-driven thin-skinned extension above inclined salt layers has played an important part in North Sea basin development. Commercial section restoration software has been used to facilitate depth conversion, restoration and decompaction of seismic sections selected from an interpreted regional database in the western central North Sea, allowing validation of the interpretations, and a graphical and highly quantitative description of salt-assisted extension. Results of this work show that Zechstein Group evaporites were deposited in shallow sag basins during the Permian. Triassic sedimentary pods were generated by localized deposition in synclinal basins and grabens above the evaporites. Bedded salt became folded, while mobile salt flowed to fill anticline cores. Since the early Jurassic, regional tectonic tilting related to post-rift subsidence and increasing sedimentary overburden have caused allochthonous Mesozoic and Tertiary strata to extend by gravity spreading above the mobile salt layer, which detaches the allochthon from the underlying autochthonous Late Palaeozoic rocks. Concave-up listric normal faults sole out in the salt layer, propagate into the overlying cover sewuence, and have been active at different geological times causing stratal thickening and folding within the allochthon. Antithetic and synthetic normal faults have developed, producing complex upward branching fault systems. In map view, the listric faults form curvilinear en echelon arrays, the faults linked by relay ramps. Fault blocks are typically 3–7 km wide, 2–3 km thick and 7–10 km long. Salt movement during the Jurassic-Tertiary has been driven by active extension of the cover, causing salt to fill potential voids created by fault block rotation. Thus salt highs occur beneath sites of extension. The listric faults generally dip in the same direction as the sub-salt surface, although there are also some major counter-regional faults. During extension, regional dips have increased up to about 5, which is sufficient for gravity-driven extension above a salt layer. A total extension of about 6% has occurred. The gravity-driven thin-skinned extension documented in the western central North Sea is a phenomenon which can be recognized elsewhere in the North Sea basin, and can be readily compared with similar phenomena already documented in offshore Angola, Brazil, Nova Scotia and the Gulf of Mexico.

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: Temperature and ration level can differentially affect growth and life history characteristics of marine organisms. In this experiment we reared juvenile cuttlefish, Sepia elliptica, under two feeding regimes (satiation and half satiation) and two temperature regimes (25 and 30°C). This study examined differences in somatic growth, muscle tissue structure and composition as a function of temperature and food levels. We estimated body mass and the concentration of water, carbohydrate, protein and lipid in the mantle muscle tissue for each individual. Both high water temperature and high feeding rations increased growth rates. Temperature appeared to change the rates of muscle fibre generation and fibre growth similarly. In contrast, the ration level altered the relative rates of fibre production and fibre growth. The muscle tissue of individuals reared at 30°C had higher concentrations of carbohydrate and protein. In contrast, increasing ration levels only increased carbohydrate concentrations in the muscle tissue. The muscle tissue of reared juveniles had lower concentrations of carbohydrate and protein than wild individuals of similar size. In conclusion, water temperature and feeding levels both affect somatic growth, but the nature of the effect at the sub-organismal level differs.

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: Distribution of elements in statoliths of squid Loligo vulgaris reynaudii d'Orbigny, 1845 was studied, using the true elemental imaging system (Dynamic Analysis) of the NAC nuclear microprobe. The analysis revealed various patterns of Ca and Sr distributions. The biological interpretation of the most frequent pattern is linked with the role of Sr in the statolith deposition process. Other patterns are linked with the technique used and the specific characteristics of the sample. Traces of other elements (Cr, Mn, Fe, Cu, Zn, Br, Pb) were also found. Likewise, their presence may have the biological interpretation (Zn, Cu and Br), or is an artefact linked to the methods and conditions of sample preparation and/or analysis. Methodical aspects of using proton backscattering for PIXE X-ray yield corrections are also discussed.

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: We have determined the content of free l-amino acids and d-aspartate in the nervous tissue of three representative cephalopods: Sepia officinalis, Octopus vulgaris, and Loligo vulgaris, and the optic lobes of adult and embryo Sepia officinalis. Taurine is the most abundant amino acid in the cephalopod nervous tissue. Its content amounts to more than 50% of the total free amino acids. The other most concentrated amino acids are Glu, Ala, Asp, and GABA. High concentrations of d-aspartate were found in the nervous tissue of all cephalopods examined (7–12 μmol/g wet tissue) which represents 50–80% of the total aspartate (d + l), depending on the animal. Among the various regions of the brain of Octopus vulgaris, d-aspartate was found to be evenly distributed in the various regions of the brain. In nerve tissue of Sepia officinalis, there is no significant difference in the pattern of free l-amino acids, in particular of the d-aspartate concentration, between adults and embryos, except for GABA, Gly, His and Thr. This suggests that d-aspartate in nerve tissue of the Cephalopoda is of endogenous origin and not a product of accumulation from exogenous sources. From a comparative study of the content of d-aspartate in the nervous tissue of different animals, we found that protostomia contain a significantly higher amount than deuterostomia. Thus, d-aspartate could be a criterion to distinguish the protostomia phyla from the deuterostomia phyla.

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: Three hundred and fifty individuals of 12 species of cephalopods which differed in their feeding habitats were sampled from the French Atlantic coast to the sub-Arctic region (Bay of Biscay, English Channel, west Irish coast and Faroe Islands) and analysed for their cadmium contents. Comparison of the Cd levels of the cephalopods showed that those from the sub-Arctic area contained very high Cd concentrations compared to those from lower latitudes such as along the French Atlantic coast. High Cd levels in cephalopods from the sub-Arctic zone correspond closely to the reported high Cd concentrations in the tissues of top vertebrate predators from the same area. Comparison of the weekly Cd intakes for the Faroe Island pilot whales with the `Provisional Tolerable Weekly Intake' for humans recommended by the World Health Organisation, showed that top vertebrate predators are often subjected to Cd doses far in excess of those recommended for humans. Our limited survey results suggest that cephalopods constitute an important source of Cd for cephalopod predators, and that this bioaccumulation effect is most evident at high latitudes.

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: Basic biological parameters of cuttlefish, Sepia officinalis, in the English Channel are described from samples of commercial and research vessel landings made between April 1994 and September 1995. There was a significant difference between the length–weight relationship of male and female cuttlefish. Growth of both sexes was rapid and seasonal during the last 12 months of life. Males grew faster than females, and reached larger overall lengths and weights. Most males reached maturity before the start of their second winter, although the testis continued to develop until spawning took place the following spring. Female maturation began later and was more prolonged such that it was completed towards the end of the second winter. Adults of both sexes spawned after the second winter between late March and July. Commercial landings data showed spawning cuttlefish initially arrived on inshore grounds in the western Channel, but slightly later and in greater numbers on the inshore grounds of the middle and eastern Channel. The weight and value of cuttlefish landings made by UK vessels in the Channel increased greatly between the mid 1980s and the mid 1990s such that cuttlefish are now a major part of the earnings for several fisheries. The most important fisheries were the offshore beam trawls, and inshore otter trawls and nets. The exploitation pattern of each fishery is described from quarterly samples of commercial landings taken between April 1994 and March 1996. Each exploitation pattern is shown to be a function of the region fished, the catching gear employed, and the growth and migrations of the cuttlefish population. Some implications for stock management are discussed.

Description: The use of marine parasites as non-intrusive natural tags of their hosts was first broadly applied in fisheries science in the 1940s. Both micro- and macroparasites have been used to assess the status of current stocks of several commercially exploited species of marine animals. Here, Santiago Pascual and Eric Hochberg offer a brief comment on marine parasite tags as a stock assessment methodology, with special reference to cephalopod hosts.

Description: Laboratory rearing of 19 Octopus mimus from 40 to 589 g at 20.1±1.8°C (September to December 1991) provided information on the growth pattern and variation in instantaneous relative growth rate (G) of this Chilean littoral octopus. The three smallest specimens (ranging from 40 to 49.8 g) attained an average weight of 558 g in 70 days. Growth of this species had two phases. Growth was exponential during the first 40 days of culture with an average G of 5.33%. It slowed and became logarithmic when the animals attained weights ranging from 326.6 to 439 g. Instantaneous relative growth rate decreased from 2.25% to 0.99% during the logarithmic phase. A similar pattern was found for the 16 larger specimens (61.4–406.4 g initial weight). The change in growth pattern observed between the exponential and logarithmic phases occurred at body weights ranging from 326.6 to 454.2 g. No differences in growth were found between sexes in O. mimus. The growth pattern of this species is discussed and compared to other small-egged octopus species raised in captivity.

Description: Cephalopods are highly visual animals; the importance of chemical perception to these complex mollusks is less well understood. In this experiment, ventilation rate was used to measure the perception of chemical stimuli by cultured juvenile cuttlefish. The test tank had opaque sides and top to visually isolate the cuttlefish. A clear bottom permitted direct observation of funnel movements associated with ventilation. Cuttlefish cannot see beneath them when resting on the bottom; trials began once cuttlefish had remained calmly on the bottom for at least 15 min. The chemical stimulus was placed in a tank located upstream from the test tank containing a single cuttlefish; the cuttlefish's ventilation cycles were measured by direct observation. Ventilation rate increased significantly after exposure to ink from a conspecific, water containing food, water containing a conspecific, novel seawater and water that had contained sea turtles, potential predators. Results were obtained despite any background chemicals remaining within the closed sea water system, suggesting findings are probably robust to the conditions cuttlefish would normally experience in the ocean. Results are consistent with those obtained using visual stimuli and extend previous research indicating that cephalopods are capable of using chemical cues to detect salient environmental features.

Description: A total of 6171 specimens of Octopus mimus was collected from the commercial small-scale fishery in northern Chilean waters (off Iquique) between January 1991 and March 1992. The animals were grouped by sex, size and month for modal progression analysis (MPA). Total length of the animals ranged from 24 (66 g) to 107 cm (4358 g) for males and from 28 (63 g) to 115 cm (3714 g) for females. There were no significant differences in the length–weight relationship between sexes except in summer. The size structure of the exploited population of O. mimus is rather complex and MPA indicated six sub-annual cohorts for males and five for females. Instantaneous relative growth rate (G) in total body weight varied from 0.29% to 1.37% d−1 and from 0.23% to 1.78% d−1 for males and females, respectively. Seasonality and water temperature affected G in both sexes. Differences in G among sub-annual cohorts within the same season were found and it was observed that G tended to decrease with size.

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: Large numbers of seabirds are killed each year within the Australian Fishing Zone (AFZ) by Japanese longline vessels targeting tuna. In recent years the estimated rate of seabird bycatch in the AFZ has been in the order of 0.15 birds/1000 hooks, translating to mortalities of 1000–3500 birds per year. These estimates are absolute minima because not all birds killed remain on hooks to be observed hauled aboard the vessels. The observed seabird catch rate varies annually, seasonally and spatially. Most birds are killed: (a) during the summer fishing season (October to March), even though most fishing effort occurs in winter; (b) when longlines are set during the day; (c) in the waters around southern Australia. Uncertainties in the observed catch rates prevent confident assessment of trends, but seabird catch rates do not appear to be showing a sustained decrease. The process of the incidental collection of seabird bycatch data (by observers whose priority is to fish sampling tasks) renders the seabird bycatch data inadequate for reliable assessment of trends in total numbers of birds killed over time. Sixteen seabird species of birds killed on longlines in the AFZ have been identified. These include black-browed (Diomedea melanophris), shy (D. cauta), grey-headed (D. chrysostoma), yellow-nosed (D. chlororhynchos) and wandering albatrosses (D. exulans), flesh-footed shearwaters (Puffinus carneipes) and white-chinned petrels (Procellaria aequinoctialis). Seventy-four per cent of birds killed were albatrosses and the species composition of the bycatch varied with seasons and areas. Most species of birds killed were characterised by unequal representation of sex and age cohorts, and these unequal representations were not consistent between fishing grounds or seasons.

Description: NA and protein concentrations, and the RNA to protein ratio, were measured in four species of cephalopods, to evaluate sources of variation and the potential for using RNA concentration and the RNA to protein ratio as growth indices. In field samples of Loligo forbesi and Eledone cirrhosa, RNA concentrations and the RNA to protein ratio were higher in immature animals than in mature animals. In Loligo forbesi, values were also higher in males than in females and higher in smaller individuals than in large individuals. Both these trends are consistent with expected differences in growth rate, i.e. RNA is higher in faster growing animals. Mature female Eledone cirrhosa, a species in which the female is larger and presumably grows faster, had higher RNA concentrations than mature males. However, no such difference between the sexes was seen for immature E. cirrhosa or Todarodes sagittatus. Methods for transport and maintenance of Loligo forbesi in captivity in the Azores are described. Many of the captive squid showed poor growth and survival but results from these animals nevertheless confirmed that RNA concentrations were higher in males than in females and higher in animals with smaller gonads than in animals with large gonads. Higher protein concentrations were found in males than in females, and protein concentration was also positively correlated with feeding rate and digestive gland indices. Octopus vulgaris held in captivity grew rapidly and consistently and RNA concentrations were lower in bigger animals than in smaller animals. Neither experiment provided direct support for the hypothesis that RNA concentration or the RNA to protein ratio is directly related to growth rate. Systematic variation in protein concentration, e.g. in relation to recent feeding, leads us to suggest that protein concentration (mg/g fresh body weight) is likely to provide a more reliable index than the RNA to protein ratio.

Description: This review is based on the author's own data and all available published data (mostly Russian and Japanese) on the ecology, biogeography and role in the ecosystem of gonatid squids in the northern North Pacific. For the best studied species, Berryteuthis magister, information is given on size, horizontal and vertical distribution, diel and ontogenetic vertical migrations, maturation, mating, spawning, fecundity, population structure, age, growth, life cycle, horizontal migrations, underwater behaviour, food and feeding, and predators. The assessed biomass and its interannual dynamics and the fisheries importance are also covered. For other, less studied, species of the genera Berryteuthis (B. anonychus), Gonatopsis (three species) and Gonatus (seven species) all available ecological and biogeographical data are included. All species are compared according to their size, horizontal and vertical distribution, spawning habitats, diel vertical migrations and gelatinous degeneration associated with maturation. The “ecological individuality” of each species is evaluated. It is shown that each occupies its own ecological niche but these niches overlap to different degrees. The history of niche divergence in North Pacific gonatids during the Neogene-Pleistocene period is briefly reviewed. Common features are described of the horizontal and vertical distribution, relative abundance and biomass of North Pacific gonatids in general. Their roles in the ecosystem, as predators, prey, competitors and hosts of parasites is evaluated. The total biomass of gonatid squids in the whole subarctic North Pacific and the Russian Far Eastern seas is estimated as approximately 15–20 million t. They contribute some 10–15% of the total production of mesopelagic cephalopods in the World Ocean. Their yearly food consumption is assessed at 100–200 million t. The life cycle of gonatids is shorter and their P/B-coefficient much higher than that of subarctic mesopelagic fishes. As a result, though the squid biomass (calculations for the Okhotsk Sea) is less than 10% of the total mesopelagic fish and squid population, they form 58–67% of annual total fish and squid production. Thus gonatid squids have an important place in the ecosystem of the northern North Pacific and the Far Eastern seas of Russia.

Description: Some aspects of the biology and fishery of Octopus vulgaris caught by trawlers in the Balearic Sea (Western Mediterranean) are studied. The analysis of the size–frequency distribution followed the growth of specimens from January (6–7 cm ML) to August (11–12 cm ML). The sex ratio was estimated for each season and it was not significantly different from 1 : 1 in any of them. The stomach contents revealed that the octopus fed predominantly on crustaceans and fishes. Another octopus species, Eledone moschata, is present in this fishery but its catches were clearly lower than those of O. vulgaris. The analysis of the importance of these two species in relation to the rest of the commercial catch showed that octopuses represent between 20–40% of the total catch for trawlers. The highest catch rates (kg/h) were obtained in spring and at the beginning of summer. Time-series analysis of monthly catches from January 1981 to August 1996 showed two main oscillations. The lower one, with a periodicity of 12 months, reflects the annual biological cycle of the species; on the other hand, the higher one has a periodicity of 92 months, the time series available being too short to confirm the significance of this period.

Description: This paper presents data on the diet of the squid, Loligo vulgaris (Lamarck, 1799) from the south coast of Portugal (Algarve) and from the Saharan Bank (Central-East Atlantic). A total of 964 squid was collected from the Algarve coast, between March 1993 and October 1994, from bottom trawling. An additional sample of 70 stomachs was obtained in the Algarve coast from the hand jigging fishery during 1991 and 1992. In the Saharan Bank, 848 squid were obtained, between June 1993 and January 1994, with bottom trawling. Stomachs with contents for trawled squid from the Algarve coast, and the Saharan Bank represented 28.1% and 40.8%, respectively. Fish was always the main component of the diet in both regions, representing 88.6% of the total weight of the prey found in the stomachs, for the Algarve coast, and 70.9% for the Saharan Bank. The occurrence percentage and the percentage in number indicated that Trachurus trachurus and fish belonging to the family Gobiidae were the most frequent fish found in the Algarve samples, while flatfish were the most common fish in the Saharan Bank samples. Loligo vulgaris was the dominant cephalopod found in the stomachs for both regions. No differences in the diet were found between males and females. The comparison between immature and mature squid showed that the importance of fish was higher in mature squid, for both regions. The squid captured from the Algarve coast by bottom trawling (at greater depths and offshore) fed primarily on fish, while those captured with hand jigging (inshore, at lower depths) contained an important percentage of crustaceans.

Description: Male cuttlefish adopt a specific body pattern during agonistic behaviour called the Intense Zebra Display. Some components of the Display were variable, especially the chromatic component termed ‘dark face’, which could vary in the degree of darkness. Facial darkness was measured using a video analysis system. Males that eventually withdrew from conspecifics without fighting maintained a lighter face during the initial stage of agonistic encounters. When both males maintained dark faces, physical contact and fighting ensued. Therefore facial darkness could be used to predict which male–male encounters would escalate to physical contact. The strong correlation between facial darkness and subsequent behaviour suggested that males were signalling their agonistic motivation at the early stages of the encounter, which is contrary to what would be predicted from a traditional game theory analysis. It is proposed that males signal intent because the Intense Zebra Display simultaneously serves two functions: (1) it identifies the signaller as male, thus preventing unwanted copulations from other males, and (2) it functions as part of the agonistic behavioural repertoire. By using a modified (i.e. lighter-faced) version of the Display, males may be able to signal their sex, but without inducing another male to attack. In cases in which agonistic displays perform more than one function, signalling intent (i.e. signalling its likely subsequent behaviour) can be an evolutionarily stable strategy.

Description: Longitudinal sections of statoliths were observed by light microscopy on 237 individuals (158–510 mm mantle length, ML) of Ommastrephes bartrami, obtained from the North Pacific (26 °–46 °N, 143 °E–149 °W) during 1991–1994. The width of each increment sharply decreased from 5–7 μm to about 1–2 μm between the 80th and 100th increment, with a transition zone where increments were inconspicuous. ML-age relationships were linear, and slope and intercept values differed by geographic area, hatch season and sex. Overall growth rates (mm day−1) were generally higher in females (1.1–2.5) than in males (1.1–2.1). Since these values were similar to the growth rates of four individuals which were tagged and recaptured (0.8–2.4), the increments were assumed to be formed daily. The growth rate was highest for individuals hatched in summer, followed by those hatched in spring. Growth rate obtained by length-based methods may be underestimated. The hatch dates of neon flying squid are almost year-round, and the life span is likely 1 year since mature individuals were 7–10 months old.

Description: The cuttlefish Sepia pharaonis (maximum 250 mm mantle length, ML) and S. dollfusi (maximum 150 mm ML) are widely distributed in the Indo-Pacific from the Red Sea to Japan and Australia. They are the primary fishery in the Suez Canal and the most valuable commercial cephalopods in the northern Indian Ocean. However, their reproductive biology, essential for fishery management, is poorly known. Four maturity stages were described using morphology and histology. Based on the proportions of each maturity stage, as well as various maturity indices, spawning was found to take place from March to June for S. pharaonis and January to April for S. dollfusi. The size at maturity for S. pharaonis was 61 and 122 mm ML for males and females, respectively. In contrast, the size at maturity for S. dollfusi was similar in both the sexes (75 and 84 mm ML for males and females, respectively). Fecundity was estimated by counting the number of maturing and mature ova, which varied from 75 to 1525 for S. pharaonis and 30 to 273 for S. dollfusi. The monthly size-frequency distribution of ova provides evidence for the accuracy of the fecundity estimates. The data suggest that reproduction extends over ≈6–9 months; this probably represents the latter 1/2–2/3 of the life cycle, and may be typical for sepioid and teuthoid cephalopods.

Description: The feeding ecology of Greenland halibut (Reinhardtius hippoglossoides) on the deep slope of the northeast Newfoundland continental shelf was investigated based on stomach analysis. Stomach samples were collected from the spring 1992 Canadian bottom trawl fishery at depths of 1000–1250 m. The squid, Gonatus spp., predominated in the diet, representing the first known instance of reliance of Greenland halibut upon this bathypelagic squid as prey in Canadian waters. A change from predation primarily upon pelagic prey, reported in earlier studies, may be related to annual variability in abundance and distribution of both Greenland halibut and its principal pelagic fish prey species, capelin (Mallotus villosus). Seasonal effects may account for the absence of epipelagic, juvenile Gonatus spp. from the diet. There was a linear size relationship in observed predation which may reflect a common size-related depth distribution pattern between predator and prey or, more likely, prey selectivity. At larger sizes, Greenland halibut switched from Gonatus spp. to groundfish as its principal prey. The importance of Gonatus spp. in the deep continental slope trophic web is reviewed.

Description: A small-scale trap fishery for many benthic species is carried out along the coastal shelves of the Canary Islands (Central-East Atlantic) by small boats (7.5 to 12.4 m in length). The target species of the fishery are seabreams (Sparidae), but substantial numbers of octopus (Octopus vulgaris) are also landed. In this paper, we report fishing data for octopus landed at the port of Mogán (Southwest of Gran Canaria) from 1989 to 1996. The landing of O. vulgaris increased steadily from 1989 to 1994, from 7 t to 25 t. However, in 1995, the catch fell to the level of 1989 (7 t), and in 1996 was only 6 t, the lowest figure for the decade. The CPUE shows two seasonal peaks of maximal abundance, one in April–May and the other in September–November, both coinciding with reproductive periods, while the lowest figure is in summer (July–August). We describe the fishing methods and the seasonal variations of the catch records and fishing effort in relation to years and market strategies.