ALBERT

Description: RECENT advances in 40Ar/39Ar dating1,2 have made it possible to date individual K-feldspar grains from Pleistocene tephra, a capability that greatly improves the reliability and temporal resolving power of the method. Here we apply these new techniques to the dating of a phonolite tephra from the East Eifel volcanic field in West Germany, which is sandwiched between loess and palaeosol (alfisol) deposits, and which was therefore erupted during the transition from a glacial to an interglacial period. Our age estimate for this transition is 215±4 kyr (1 σ), which has important implications for the marine δ18O timescale and for models of global climate change during the Pleistocene. The results show that single-grain dating can detect and compensate for the large quantities of xenocrystic contaminants which are found in many tephra deposits. This technique could be used to date the tephra layers found in marine sediment cores and the results could greatly enhance the reliability of the marine δ18O timescale for more rigorous Fourier analysis testing of the Milankovitch hypothesis.

Description: 1 Zonation is often seen in environments with a strong physico-chemical gradient, such as salt marshes. It has been hypothesized that plant species are limited in their distribution by abiotic factors towards the more extreme end of the gradient, and by competition towards the more favourable end. Invasion of the native clonal grass genus Elymus in many Wadden Sea marshes may be due to increasing atmospheric nitrogen input into a nitrogen-limited environment. However, at Thmlauer Bay, Germany, Elymus athericus does not occur in lower salt marsh communities that are dominated by a dwarf shrub (Atriplex portulacoides). We therefore hypothesized that at this site the downslope (= more extreme) distributional boundary of E. athericus is a result of competition with A. portulacoides rather than of physiological limits. 2 A factorial experiment was set up to investigate the effects of removal of each competitor and fertilization. The reciprocal effects of the species on each other were measured in terms of vegetation cover and above-ground biomass. The impact of the tidal regime on plant zonation was investigated by calculating inundation frequencies at the boundary between the two plant populations from water level recordings. 3 Elymus athericus extended its distribution into the lower salt marsh when A. portulacoides was removed. The latter increased in cover but not in biomass after the removal of E. athericus. Neither species showed a response to nitrogen fertilization. The boundary between the two species in the control plots varied considerably in elevation and inundation frequency. 4 The lower distributional boundary of E. athericus can be interpreted as the result of competition with A. portulacoides. Improvement of nitrogen availability in concentrations of the same order of magnitude as annual atmospheric input had no detectable effect on plant zonation and growth. Elevation and inundation frequency were not strictly correlated with plant zonation.

Description: A new species of the holopodid genus Cyathidium was found on rocks off Grande Comore in a depth of around 200 m. Based on external morphology of resting animals, the new species Cyathidium plantei sp. n is described, with emphasis on comparison to the only other extant species (C. foresti) as well as to the four extinct representatives of the genus. Concerning morphological characters, the new species is almost identical to the Cretaceous C. depressum. A cladistic analysis of the entire family, including the genus Holopus, shares a peculiar pattern of bending of the arms, which in principle is an apomorphic character of the family and in detail shows variations within the family. In addition, stratigraphic data are used for the determination of the evolutionary direction. This analysis reveals that the two recent species are closely related to each other, and to the fossil C. depressum. from which the entire family is probably derived.

Description: The chapter gives an overview of marine plant relationships with their environment, wich is called ecology. The overview is a requirement to understanding the biology of marine plants because they do not live as isolated units. Consideration will be given to basic tenets of marine ecology including levels of organization (Populations to ecosystems), processes of community development (succession, energy transfer), strategies (evolutionary, plant responses), biological iunteractions (forms of symbiosis, competition, predation), and growth (rates and responses).

Description: A protein unique to phosphorus stress observed in Dunaliella tertiolecta Butcher was studied in the context of phosphate‐limited cell physiology and is a potential diagnostic indicator of phosphate deficiency in this alga. Cells were grown over a range of limited, steady‐state growth rates and at maximum (replete) and zero (phosphate‐starved) growth rates. The stress protein, absent in nutrient‐replete cells, was produced under all steady‐state phosphate‐limited conditions and increased in abundance with increasing limitation (decreasing growth rate). Cellular carbon: phosphorus ratios and the maximum uptake rate of phosphate (Vm) increased with increasing limitation, whereas the ratio of chlorophyll a: carbon decreased. Alkaline phosphatase activity did not respond to limitation but was measurable in starved, stationary‐phase cells. Fv/Fm, a measure of photochemical efficiency, was a nonlinear, saturating function of p, as commonly observed under N limitation. The maximum Fv/Fm of 0.64 was measured in nutrient‐replete cells growing at μmax, and a value of zero was measured in stationary‐phase starved cells. When physiological parameters were compared, the P‐stress protein abundance and Fv/Fm were the most sensitive indicators of the level of deficiency. The stress protein was not produced under N‐ or Fe‐limited conditions. It is of high molecular weight (〉200) and is associated with internal cell membranes. The stress protein has several characteristics that make it a potential diagnostic indicator: it is 1) unique to phosphorus limitation (i.e. absent under all other conditions), 2) present under limiting as well as starved conditions, 3) sensitive to the level of limitation, and 4) observable without time‐course incubation of live samples.

Description: Marine Upper Jurassic sediments have recently been reported from South Africa (Knysna Outlier, Cape Province) for the first time1. They occur as shallow water, sandy clays (Brenton Beds) in association with terrestrial/fluviatile conglomerates and sandstones, which were deposited in an approximately east-west elongate intermontane basin between the Cape Fold mountains (formed of Lower Palaeozoic sediments). Post-Cretaceous erosion has reduced the original deposits to a series of small, isolated outliers, only two of which have been reported to contain marine sediments (Knysna, lower Upper Jurassic; Algoa, Valanginian2) (Fig. 1). Extensive Neocomian-Maas-trichtian outcrops are known from the continental shelf off to the south of South Africa3, and a complete mid-Jurassic to Upper Cretaceous marine succession is suspected on the Agulhas Bank infilling and overlying east-west striking, fault bounded folds of Lower Palaeozoic Cape Supergroup rocks as shown in Fig. 1 (R. V. D., in preparation and refs. 1 and 4).

Description: Hurricanes and other strong storms can cause important decreases in sea surface temperature by means of vertical mixing within the upper ocean, and by air–sea heat exchange. Here we use satellite-derived infrared images of the western North Atlantic to study sea surface cooling caused by hurricane Gloria (1985). Significant regional variations in sea surface cooling are well correlated with hydrographic conditions. The greatest cooling (up to 5°C) occurred in slope waters north of the Gulf Stream where the seasonal thermocline is shallowest and most compressed; moderate cooling (up to 3 °C) occurred in the open Sargasso Sea where the thermocline is deeper and more diffused; little or no cooling occurred in shallow coastal waters (bottom depth less than 20 m) which were isothermal before the passage of hurricane Gloria. There is a pronounced right-side asymmetry of sea surface cooling with stronger (by a factor of 4) and more extensive (by a factor of 3) cooling found on the right side of the hurricane track. These qualitative results are consistent with the notion that vertical mixing within the upper ocean is the dominant sea surface cooling mechanism of hurricanes.

Description: Heavy mineral studies of East Siberian river sediments, Laptev Sea surface sediments, and a sediment core of the western Laptev Sea were carried out in order to reconstruct the pathways of modern and ancient sediment transport from the Siberian hinterland to the Laptev Sea. The modern heavy mineral distribution of Laptev Sea surface sediments reflects mainly the riverine input. While the eastern and central part of the Laptev Sea is dominated by amphibole, which is supplied by the Lena River, the western part is dominated by pyroxene imported from the Siberian Trap basalts by the Khatanga River. The distribution of garnet and opaque minerals is additionally influenced by hydrodynamic processes. As a consequence of their high density, these minerals are predominantly deposited close to the river mouths. Heavy mineral and sedimentological studies of a sediment core of the western Laptev Sea were applied to reconstruct the postglacial history of the shelf area during the last 11 ka. In the lowermost interval of the core (〉c. 10 ka), high accumulation rates and a heavy mineral composition similar to that of the modern Khatanga river indicate fluvial conditions. Additionally, the high mica content in this interval may indicate meltwater inflow from the Byrranga mountains. Strong variations in accumulation rates, grain-size distribution, and heavy mineral composition are observed in the time interval between c. 10 and 6 ka, which represents the main transgression of the Laptev Sea shelf. During the uppermost interval (〈6 ka), rather stable conditions similar to the modem situation prevailed.

Description: The influence of mixing frequency and depth on phytoplankton functional group composition (mobile versus immobile species) was studied by enclosure experiments in a shallow, stratified lake. Mixing events were artificially induced at intervals from 2–12 d. The mixing depth was increased from the natural level (4 m) to 6 and 9 m. The mobile phytoplankton in the experiments consisted of cyanobacteria and flagellates. Among the latter, large and rapid swimming species were represented by dinoflagellates. An increase of the relative abundance of gas vacuolated cyanobacteria occurred with increasing frequency of mixing. Additionally Reynolds' hypothesis predicting the occurrence of certain mobile phytoplankton genera in response to the mixing regime could be confirmed for the condition when mixing depth exceeds the euphoric depth.

Description: Ship speed may have an important effect on the results of seabird surveys. We counted seabirds on a 20.5 X 0.3 km transect in the Kattegat that was sailed nine times with the RV "Heincke." Ship speed alternated between 9 knots and 5 knots. The numbers of the most common species, the Lesser Black-backed Gull (Larusfuscus), were significantly higher when the ship was sailing at lower speed similar to that of commercial fishing vessel when trawling in the area. It is postulated that scavenging species( e.g., gulls) are attracte to the low speed of vessels whereas non-scavengers (e.g. auks) are not

Description: The ability to monitor the heat content of oceans over long distances is becoming increasingly important for understanding the role of oceans in climate change, for determining the variability of the state of the oceans, for operational ocean observing systems, and for studying large-scale ocean processes such as water-mass formation. Although the properties of the upper layers of the ocean can be routinely measured on large scales by satellite remote sensing (providing altimetric and infrared data) and with expendable probes dropped from commercial vessels, the deep interior of the ocean is more difficult to monitor. Ocean acoustic tomography1 is a promising technique for such applications, as it has the potential to provide systematic, instantaneous and repeated measurements of the ocean interior over large parts of an ocean basin. Here we demonstrate the capability of this technique for measuring the heat content across an entire (albeit small) ocean basin—the western Mediterranean Sea.

Description: The identification of developmental stages in fish eggs from plankton samples is often complicated by deformation of the embryos due to mechanical stress during the sampling procedure and by dehydration during formaldehyde fixation. The effects of formaldehyde fixation and mechanical stress on Baltic cod eggs (Gadus morhua callarias L.) were examined separately by visually comparing the morphological features of treated vs. live eggs of identical ontogenetic age. Microphotographs were made concurrently for documentation. In stage IA eggs, mechanical treatment resulted in scattered blastodiscs surrounded by single cells, while in further advanced stages the yolk membrane collapsed entirely, the yolk coagulated and the embryo extending over the yolk shrank. Formaldehyde fixation caused the yolk and the blastodisc or embryo to darken, and in some cases crystalline enclosures occurred. Eggs mechanically deformed during handling were clearly distinguishable from those that died prior to catching; however, staging was generally less accurate for formaldehyde-preserved eggs when compared with living specimens.

Description: The conventional model whereby plume volcanism forms linear age-progressive volcanic chains, with the youngest activity occurring nearest a spreading axis (at a 'hotspot'), has been challenged for the Easter seamount chain1–4. Whereas early work suggested the existence of a linear melting anomaly (a 'hotline')1,2, more recent studies3,4 have proposed a hotspot near Salas y Gomez island, connected with the Easter microplate spreading system by an ~800-km-long, volcanically active plume channel. Here we use geochemical, geological and geochronological data to argue that the hotspot lies close to Easter Island. Moreover, new isotopic data for lavas from the seamount chain provide evidence for bidirectional flow between the spreading axis and the plume, thus supporting geophysical and fluid-dynamical models of mantle flow in a plume/spreading axis system5–7. Material balance and flux considerations show the Easter plume to be weak and cool compared with those beneath larger features such as Iceland, Hawaii and the Galápagos islands.

Description: The holocene depositional setting of the Laptev Sea was studied using three marine sediment cores from water depths between 77 and 46 m. Based on sedimentary parameters (TOC content, delta(13)C(org) Sedimentation rates) controlled by radiocarbon age models the palaeoenvironment of a strongly coupled river-shelf system was reconstructed since similar to 11 ka SP. Caused by a transgressing sea after the last glaciation, all cores reveal progressive decreases in sedimentation rates. Using the sedimentary records of a core from the Khatanga-Anabar river channel in the western Laptev Sea, several phases of change are recognized: (1) an early period lasted until similar to 10 ka BP characterized by an increased deposition of plant debris due to shelf erosion and fluvial runoff; (2) a transitional phase with consistently increasing marine conditions until 6 ka BP, which was marked at its beginning near 10 ka BP by the first occurrence of marine bivalves, high TOC content and an increase in delta(13)C(org); (3) a time of extremely slow deposition of sediments, commencing at,6 ka BP and interpreted as Holocene sea-level highstand, which caused a southward retreat of the depositional centres within the now submerged river channels on the shelf; (4) a final phase with the establishment of modern conditions after similar to 2 ka BP.

Description: At a subtidal, soft-bottom site in the western Baltic Sea, mussel (Mytilus edulis) patches co-occur with high predator abundances. Sea star (Asterias rubens) biomasses, in particular, exceed reported values considered sufficient for restricting mussels to the intertidal zone. To determine how mussels can persist in the face of intense predation, we decomposed patch space occupancy into the relative contributions of newly arriving individuals (recruitment) and of increases in body size of the individuals already present in the patch over 13 mo. Sea stars, as major predators, were only able to control 77% of the potential per capita recruitment rate of 91 individuals/yr in 2 m depth. The remaining recruitment rate of 21 individuals/yr was sufficient to allow patches to occupy 1.6 times more space per year. Transplantation of patches to 6 m depth, where recruitment is negligible, revealed that sea stars were also ineffective in controlling mussel coverage through consumption of larger mussels (〉1 yr, 〉30 mm shell length). In deeper water, space occupancy of patches through increases in mussel body size was able to balance predation mortality, demonstrating that mussels attained a relative refuge in size at only 33 mm shell length. Based on the measured shell growth rates, mussels attain this size after ≈15 mo. In situ observations of Asterias feeding activity, the ratios between necessary predator sizes to attack prey of a given size, and predator size distributions suggest that sea stars were on average too small to feed effectively on adult (〉1 yr) mussels. Probably, Asterias cannot respond to abundant prey and increase its maximal body size at the site because salinities are at its lower tolerable limit (12–18 g/kg). Thus, bottom-up factors such as high prey productivity in concert with subtle size-based ineffectiveness of the predator population allow otherwise unstable predator–prey populations of a generalist predator and its preferred prey to coexist. Although mussel predators were unable to decimate mussels to local extinction, a release of experimental mussel patches from predation with strong recruitment (2 m depth) resulted in an approximately sevenfold yearly areal increase in shallow treatments, which would lead to a 100% mussel cover at the site within 1 yr. Given that mussels can dominate both rocky substratum and soft sediment, we also studied the effect of substratum quality in factorial combination with presence/absence of predation and water depth on mussel abundance. Attachment to stable substratum did not affect recruitment to the patches or patch space occupancy, but it completely prevented patch dislodgment and subsequent drift. In contrast to rocky shores, mussel patch dislodgment may represent the major mode of patch dispersal and new patch formation in soft-bottom environments as demonstrated by a drift collector fence.

Description: High-resolution reflection seismic data obtained around Gran Canaria allow a detailed and consistent correlation of seismic reflectors of the northern and southern Canary Basins with the lithology drilled by DSDP Leg 47A SSE of Gran Canaria, as well as with major phases of volcanic activity on Gran Canaria as mapped onshore. Two prominent reflectors were chosen as marker horizons and correlated with the drilled lithology. the results indicate that reflector R7 above the Miocene volcaniclastic debris flows V1-V3 reflects the shield-building phase of Gran Canaria. Reflector R3 is interpreted as corresponding with the Pliocene Roque Nublo formation. The top of the massive island flank of Gran Canaria, defined by seismically chaotic facies, extends 44 to 72 km off the coast of Gran Canaria. West of Gran Canaria the flank of Tenerife onlaps the steeper and older flank of Gran Canaria, which, in turn, is onlapping the older flank of Fuerteventura to the east in a similar way. Erosional channels, which can also be traced up to 50 km from the area between Gran Canaria and Fuerteventura into the deeper northern basin, have been identified in the bathymetry. The data presented provide new detailed information for modelling the submarine and subaerial evolution of the central Canary Islands of Gran Canaria and Tenerife, i.e. the timing of their shield-building phases and later stages of major volcanic activity, as reflected by the position of prominent seismic reflectors in the seismic stratigraphy.

Description: A knowledge of past changes in the biological productivity of the oceans is important for understanding the interactions between carbon cycling and climate. Phytoplankton productivity in today's oceans can be estimated from the concentrations of chlorophyll in sea water1, but chlorophyll is not preserved in the sediments. Existing proxies for past algal productivity do not represent total productivity; for example, biogenic opal2 reflects the contribution of only part of the phytoplankton community, and the organic carbon record can be subject to contamination from terrestrial inputs2,3. Although chlorins, the pigment-transformation products of chlorophyll, are widespread in Quaternary marine sediments, their potential as proxy measures of past variations in primary productivity has not been convincingly demonstrated. Here we report a high-resolution molecular stratigraphic record of chlorin concentrations over the past 350,000 years in a sediment core from the subtropical Atlantic continental margin. Maxima in the chlorin accumulation rate coincide with significant peaks in the accumulation rates of biogenic opal (at the end of glacial terminations) and organic carbon (between terminations). These results suggest that chlorins, unlike other proxies, can serve as a measure of total primary productivity variations.

Description: The growth of Fucus vesiculosus L, germlings in chemically defined culture media containing a range of Cu concentrations (20-1000 nM) was monitored simultaneously with measurement of the Cu speciation in the media by competitive equilibrium-adsorptive cathodic stripping voltammetry, Fucus vesiculosus germlings were found to exude Cu-complexing Ligands with conditional stability constants of the order of 1.6 x 10(11), Ligand concentrations increased with increasing total dissolved Cu concentrations (Cu-T) until a concentration of 500-800 neq Cu.L-1 was reached. Concentrations of the ligand exceeded Cu-T in treatments containing 20 and 100 nM Cu-T were similar to Cu-T in the 500-nM Cu treatment, but were less than Cu-T in the 1000-nM treatment. Therefore, [Cu2+] were calculated to be at concentrations of 10(-11) - 10(-10) M in the 20- and 100-nM treatments, 10(-9) M in the 500-nM treatment, and 10(-7) M in the 1000-nM treatment, Growth rates were lowest at Cu2+ concentration 〉 10(-9). These results are discussed within the context of the potential roles for exuded copper-complexing ligands

Description: There has been a widespread increase in the reporting of harmful and ‘nuisance’ algal blooms in the coastal ocean over the past few decades. On the global scale this is suspected to be a consequence of coastal eutrophication, however, on a case-by-case basis there is usually insufficient evidence to discriminate between the effects of human and natural causal factors. Intense blooms of the ‘Brown Tide’ unicellular algae (Aureococcus anophagefferens) have occurred sporadically since 1985 in coastal waters of Eastern Long Island and have devastated the local commercial scallop fishery. Analysis of an 11-year time-series dataset from this region indicates that bloom intensity is correlated with higher salinities and inversely correlated with the discharge of groundwater. Laboratory and field studies suggest that whereas salinity is unlikely to represent a direct physiological control on Brown Tide blooms, the addition of inorganic nitrogen tends to inhibit Brown Tide blooms. Budget calculations indicate that the inorganic nitrogen supply from groundwater is 1–2 orders of magnitude higher than any other external source of nitrogen for this ecosystem. Biweekly time series data collected in 1995 demonstrate that Brown Tide blooms utilize dissolved organic nitrogen (DON) for growth, as evidenced by a large decrease in DON parallel with an increase in cell abundance. On an interannual basis, bloom intensity was also positively correlated with mean DON concentrations. We hypothesize that bloom initiation is regulated by the relative supply of inorganic and organic nitrogen, determined to a large extent by temporal variability in groundwater flow. The 1980s and 1990s were characterized by exceptionally high and interannually variable groundwater discharge, associated with a large-scale climate shift over the North Atlantic. This, coupled with the time-lagged discharge of groundwater with high nitrate concentrations resulting from increased fertilizer use and population increase during the 1960s and 1970s, may have been a key factor in the initiation of Brown Tide blooms in 1985

Description: STEP-LIKE structures in temperature and salinity beneath the Mediterranean water have been observed in the Eastern Atlantic1–6. In Fig. 1 we show the stations where steps have been found in the area to the west of Gibraltar. Salt fingering as a result of double diffusive processes has been suggested as a possible cause for the generation of such step-like structures7. During cruise No. 23 of RV Meteor in 1971 we intended to study the small scale features of such structures8. Some previous observations6 in August/September 1970 had revealed an extensive zone where a “thermohaline staircase” existed (Fig. 1). We therefore selected stations in this area and close to it for the proposed study. A high resolution in situ conductivity-temperature-depth meter of the “Kieler Multi-Meeressonde” type was used for the vertical profiling of temperature and salinity.

Description: Loligo forbesi Steenstrup is a commercially and biomedically important species raneing from Scotland to North Africa and from the Azores Islands in the central Atlantic east through the Mediterranean Sea and Red Sea. Eggs were collected from Plymouth. England and from the Azores and the hatchlings were reared to adult size in recirculating seawater systems. Growth data were obtained primarily from mortalities during the course of three culture experiments which lasted 360, 240 and 480 days. Loligo forbesi hatched at a size of 5–9mg (3.0–4.6mm mantle length, ML) and grew to a maximum size of 124g (155 mm ML) in 413 days. In all experiments, growth was exponential in form for at least the first 3 months at rales of 5.8, 5.1 and 3.6% body weight per day (BW/d) at mean temperatures of 14.1, 14.0 and 13.1°C respectively. In one short-term experiment, month-old squids grew at 8.0% BW/d at 17.4°C. Growth beyond 3 months was slower and either logarithmic (as described by the power function) or exponential in form. Growth rates gradually declined to 1–2% BW/d, Analyses of mantle length growth confirmed the wet weight results. There was no evidence of sexual dimorphism in the laboratory populations, which were of small size, and the length-weight (L-W) relationships were found to be similar to those of field populations. Growth rates during the exponential growth phase appeared very sensitive to temperature, with a 1°C difference changing growth rate by 2% BW/d and producing a three-fold difference in weight at 90 days post-hatching. These dramatic effects of temperature on adult size and lifespan in nature are discussed. It is hypothesized that the small size of mature laboratory-reared squids was due to low culture temperatures during the first 3 months.

Description: The biosynthesis of Pep5, a lanthionine-containing antimicrobial peptide, is directed by the 20-kbp plasmid pED503. We identified a 7.9-kbp DNA-fragment within this plasmid which covers the information for Pep5 synthesis in the homologous host Staphylococcus epidermidis 5 which has been cured of pED503. This fragment contained, in addition to the previously described structural gene pepA and the immunity gene pepl [Reis, M., Eschbach-Bludau, M., Iglesias-Wind, M. I., Kupke, T. & Sahl, H.-G. (1994) Appl. Env. Microbiol. 60, 2876–2883], a gene pepT coding for a translocator of the ABC transporter family, a gene pepP coding for a serine protease and two genes pepB and pepC coding for putative modification enzymes; the gene arrangement is pepTIAPBC. We analyzed the biosynthetic genes with respect to their function in Pep5 biosynthesis. Deletion of PepT reduced Pep5 production to about 10%, indicating that it can be partially replaced by other host-encoded translocators. Inactivation of PepP by site-directed mutagenesis of the active-site His residue resulted in production of incorrectly processed Pep5 fragments with strongly reduced antimicrobial activity. Deletion of pepB and pepC leads to accumulation of Pep5 prepeptide in the cells without excretion of processed peptide. A pepC-deletion clone did not excrete correctly matured Pep5 but it did produce fragments from which serine and threonine were absent. Only one of these fragments contained a single lanthionine residue out of three expected while the remaining, unmodified cysteine residues could be detected by reaction with Ellman's reagent. These results demonstrate that PepC is a thioether-forming protein and strongly suggest that PepB is responsible for dehydration of serine and threonine

Description: The ocean stores and transports vast quantities of heat, fresh water, carbon and other materials, and its circulation plays an important role in determining both the Earth's climate and fundamental processes in the biosphere. Understanding the development of climate and important biological cycles therefore requires detailed knowledge of ocean circulation and its transport properties. This cannot be achieved solely through modelling, but must involve accurate observations of the spatio-temporal evolution of the global oceanic flow field. Estimates of oceanic flow are currently made on the basis of space-borne measurements of the sea surface, and monitoring of the ocean interior. Satellite altimetry and acoustic tomography are complementary for this purpose1, as the former provides detailed horizontal coverage of the surface, and the latter the requisite vertical sampling of the interior. High-quality acoustic-tomographic2 and altimetric3 data are now available to test the combined power of these technologies for estimating oceanic flows. Here we demonstrate that, with the aid of state-of-the-art numerical models, it is possible to recover from these data a detailed spatio-temporal record of flow over basin-scale volumes of fluid. Our present results are restricted to the Mediterranean Sea, but the method described here provides a powerful tool for studying oceanic circulation worldwide.

Description: The aim of this study was to evaluate the potential of a compound diet as a live prey substitute for feeding European sea bass larvae (Dicentrarchus labrax L.). The effect of a commercial diet (Nippai ML feed) and live prey (Artemia nauplii) on tryptic enzyme activity, protein content, growth (standard length) and survival rates of sea bass larvae were tested during a 27-day rearing experiment. Sea bass larvae were divided into two groups. The live food group (control group) was fed exclusively on newly hatched Artemia nauplii (Inve AF grade), the test group was fed exclusively with the compound diet from day 15 onwards. As trypsin has been demonstrated to be a useful indicator for evaluating digestibility of food and the nutritional condition of fish larvae, individual tryptic enzyme activity was determined in both feeding groups. Larvae older than 14 days after hatching and fed on live food showed a significantly higher tryptic enzyme activity than larvae fed the compound diet. A similar relationship between tryptic activity and standard length in both test groups was detected only in small larvae (standard length 〈 7 mm). The usefulness of proteolytic enzyme activity measurements in larval fish research, as well as its use in aquaculture nutrition research, was confirmed. Protein content, increase in length and survival rates of the sea bass larvae were additionally determined in order to evaluate an influence on the diet. The protein content of larvae fed the Artemia nauplii was higher and the growth of larvae fed the compound diet was reduced. Larval mortality was not affected by the diet given.

Description: Microalgal biovolume is commonly calculated to assess the relative abundance (as biomass or carbon) of co‐occurring algae varying in shape and/or size. However, a standardized set of equations for biovolume calculations from microscopically measured linear dimensions that includes the entire range of microalgal shapes is not available yet. In comparison with automated methods, the use of microscopical measurements allows high taxonomic resolution, up to the species level, and has fewer sources of error. We present a set of geometric shapes and mathematical equations for calculating biovolumes of 〉850 pelagic and benthic marine and freshwater microalgal genera. The equations are designed to minimize the effort of microscopic measurement. The similarities and differences between our proposal for standardization and previously published proposals are discussed and recommendations for quality standards given.

Description: We have prevously shown that a marine chlorophyte expressed flavodoxin under iron limitation but not under other nutrient stress conditions. Here we use polyclonal antiserum raised against the diatom Phaeodactylum tricornutum Bohlin to show that a similar response is observed in this species. Using our antibody, western blotting techniques, and standard colorimetric detection (4‐chloro‐1‐naphthol), we can detect at least a 25–50‐fold increase in flavodoxin in iron‐depleted compared to iron‐replete cells. In iron‐limited batch cultures of P. tricornulum, flavodoxin accumulation was inversely proportional to growth rate and was not detectable in cultures containing initially more than 750 nm of iron. We demonstrated that the accumulation of flavodoxin under iron stress is widespread among marine diatoms and that it may be possible to use the presence or absence of flavodoxin in natural marine diatom assemblages to detect iron limitation. However, our polyclonal antisera appears to be specific for diatoms and did not cross‐react with Synechococcus sp., Micromonas pusilla (Butcher) Manton et Parke, Dunaliella tertiolecta Butcher, Chlorella sp., Emiliania huxleii (Lohm.) Hay et Parke, or Isochrysis galbana Parke. A reverse bioassay experiment was conducted with natural phytoplankton assemblages containing mainly diatoms from Long Island Sound and in shelf waters near Cape Hatteras, two areas not suspected to be iron‐limited. Although flavodoxin was not detected in situ in these areas, natural populations of diatoms driven into iron limitation expres.sed flavodoxin. Flavodoxin was detected in mats of the diatom Rhizosolenia castracanei Cleve collected from the Equatorial Pacific during a JGOFS cruise in 1992, consistent with the hypothesis that iron may be limiting in this high‐nutrient, low‐chlorophyll region.

Description: One of the most striking features of the upper North Atlantic Ocean is an extensive layer of water with temperature close to 18°C and salinity close to 36.5‰, (ref. 1). This 18°C water is formed by winter convection in the Sargasso sea2,3, but aspects of the annual rate of 18°C water formation remain obscure4. We have simulated this water mass formation by integrating a one-dimensional model along a 4-yr trajectory of a water column circulating around the Sargasso Sea. Winter convection is deep (≥200 m) in regions where the ocean suffers a net annual heat loss to the atmosphere, and shallow (≤lOOm) where the ocean gains heat each year. The origin of the thermostad (nearly isothermal layer) is a thick layer of nearly homogeneous water subducted beneath the seasonal boundary layer in the year that the water column passes through the line dividing annual cooling from annual heating. We estimate the annual production of 18°C water to be 446,000 km3 yr−1. Downstream, more stratified central water is formed each year at a rate that depends more on Ekman pumping (wind-forced convergence) than on the decreasing depth of winter convection

Description: The El Niño/Southern Oscillation (ENSO) phenomenon is the strongest natural interannual climate fluctuation1. ENSO originates in the tropical Pacific Ocean and has large effects on the ecology of the region, but it also influences the entire global climate system and affects the societies and economies of manycountries2. ENSO can be understood as an irregular low-frequency oscillation between a warm (El Niño) and a cold (La Niña) state. The strong El Niños of 1982/1983 and 1997/1998, along with the more frequent occurrences of El Niños during the past few decades, raise the question of whether human-induced 'greenhouse' warming affects, or will affect, ENSO3. Several global climate models have been applied to transient greenhouse-gas-induced warming simulations to address this question4, 6, but the results have been debated owing to the inability of the models to fully simulate ENSO (because of their coarse equatorial resolution)7. Here we present results from a global climate model with sufficient resolution in the tropics to adequately represent the narrow equatorial upwelling and low-frequency waves. When the model is forced by a realistic future scenario of increasing greenhouse-gas concentrations, more frequent El-Niño-like conditions and stronger cold events in the tropical Pacific Ocean result

Description: We looked at the routes taken by Magellanic Penguins up the beach while moving between the sea and the colony at a breeding site in San Julian, Argentina. Birds swam parallel to the shore for a period before leaving the water to cross the beach but trajectories over the beach were not perpendicular to the water's edge but at an angle of 39°. We examined the premise that birds might be optimizing for a trade off between time or energy by adopting this procedure and found that birds can gain little or no time by walking obliquely but can, under particular circumstances, save energy. These circumstances require that the previously-calculated costs of transport for walking have been over-estimated by a factor of two

Description: In steady state, the export of photosynthetically fixed organic matter to the deep ocean has to be balanced by an upward flux of nutrients into the euphotic zone1. Indirect geochemical estimates2 of the nutrient supply to surface waters have been substantially higher than direct biological and physical measurements3, particularly in subtropical regions. A possible explanation for the apparent discrepancy is that the sampling strategy of the direct measurements has under-represented episodic nutrient injections forced by mesoscale eddy dynamics, whereas geochemical tracer budgets integrate fluxes over longer time and space scales. Here we investigate the eddy-induced nutrient supply by combining two methods potentially capable of delivering synoptic descriptions of the ocean's state on a basin scale. Remotely sensed sea-surface height data from the simultaneous TOPEX/Poseidon and ERS-1 satellite missions are assimilated into a numerical eddy-resolving coupled ecosystem–circulation model of the North Atlantic Ocean. Our results indicate that mesoscale eddy activity accounts for about one-third of the total flux of nitrate into the euphotic zone (taken to represent new production) in the subtropics and at mid-latitudes. This contribution is not sufficient to maintain the observed primary production in parts of the subtropical gyre, where alternative routes of nitrogen supply will have to be considered.

Description: Various discretization methods exist for the numerical simulation of multiphase flow in porous media. In this paper, two methods are introduced and analyzed—a full-upwind Galerkin method which belongs to the classical finite element methods, and a mixed-hybrid finite element method based on an implicit pressure–explicit saturation (IMPES) approach. Both methods are derived from the governing equations of two-phase flow. Their discretization concepts are compared in detail. Their efficiency is discussed using several examples.

Description: ROOTH proposed that the Younger Dryas cold episode, which chilled the North Atlantic region from 11,000 to 10,000 yr BP, was initiated by a diversion of meltwater from the Mississippi drainage to the St Lawrence drainage system. The link between these events is postulated to be a turnoff, during the Younger Dryas cold episode, of the North Atlantic's conveyor-belt circulation system which currently supplies an enormous amount of heat to the atmosphere over the North Atlantic region2. This turnoff is attributed to a reduction in surface-water salinity, and hence also in density, of the waters in the region where North Atlantic Deep Water (NADW) now forms. Here we present oxygen isotope and accelerator radiocarbon measurements on planktonic foraminifera from Orca Basin core EN32-PC4 which reveal a significant reduction in meltwater flow through the Mississippi River to the Gulf of Mexico from about 11,200 to 10,000 radiocarbon years ago. This finding is consistent with the record for Lake Agassiz which indicates that the meltwater from the southwestern margin of the Laurentide Ice Sheet was diverted to the northern Atlantic Ocean through the St Lawrence valley during the interval from ~11,000 to 10,000 years before present (yr BP).

Description: Current methods for the replacement of skeletal tissue in general involve the use of autografts or allografts. There are considerable drawbacks in the use of either of these tissues. In an effort to provide an alternative to traditional graft materials, a degradable 3-dimensional (3-D) osteoblast cell–polymer matrix was designed as a construct for skeletal tissue regeneration. A degradable amino acid containing polymer, poly[(methylphenoxy)(ethyl glycinato) phosphazene], was synthesized and a 3-D matrix system was prepared using a salt leaching technique. This 3-D polyphosphazene polymer matrix system, 3-D-PHOS, was then seeded with osteoblast cells for the creation of a cell–polymer matrix material. The 3-D-PHOS matrix possessed an average pore diameter of 165 μm. Environmental scanning electron microscopy revealed a reconnecting porous network throughout the polymer with an even distribution of pores over the surface of the matrix. Osteoblast cells were found attached and grew on the 3-D-PHOS at a steady rate throughout the 21-day period studied in vitro, in contrast to osteoblast growth kinetics on similar, but 2-D polyphosphazene matrices, that showed a decline in cell growth after 7 days. Characterization of 3-D-PHOS osteoblast-polymer matrices by light microscopy revealed cells growing within the pores as well as on surface of the polymer as early as day 1. This novel porous 3-D-PHOS matrix may be suitable for use as a bioerodible scaffold for regeneration of skeletal tissue.

Description: Marine organic carbon is heavier isotopically (13C enriched) than most land-plant or terrestrial organic C1. Accordingly, δ 13C values of organic C in modern marine sediments are routinely interpreted in terms of the relative proportions of marine and terrestrial sources of the preserved organic matter2,3. When independent geochemical techniques are used to evaluate the source of organic matter in Cretaceous or older rocks, those rocks containing mostly marine organic C are found typically to have lighter (more-negative) δ 13C values than rocks containing mostly terrestrial organic C. Here we conclude that marine photosynthesis in mid-Cretaceous and earlier oceans generally resulted in a greater fractionation of C isotopes and produced organic C having lighter δ 13C values. Modern marine photosynthesis may be occurring under unusual geological conditions (higher oceanic primary production rates, lower P CO2) that limit dissolved CO2 availability and minimize carbon isotope fractionation4.

Description: The climate record obtained from two long Greenland ice cores reveals several brief climate oscillations during glacial time. The most recent of these oscillations, also found in continental pollen records, has greatest impact in the area under the meteorological influence of the northern Atlantic, but none in the United States. This suggests that these oscillations are caused by fluctuations in the formation rate of deep water in the northern Atlantic. As the present production of deep water in this area is driven by an excess of evaporation over precipitation and continental runoff, atmospheric water transport may be an important element in climate change. Changes in the production rate of deep water in this sector of the ocean may push the climate system from one quasi-stable mode of operation to another.

Description: There is now clear evidence that changes in the Earth's climate may be sudden rather than gradual. It is time to put research into the build-up of carbon dioxide in the atmosphere on a better footing.

Description: Abrupt changes in climatic conditions have been seen at high latitudes in the North Atlantic and the Antarctic at 13 kyr BP. It is important to determine whether this abrupt change was confined to high-latitude regions or whether it was global. Here we present results demonstrating an abrupt change in the rate and character of sedimentation in the South China Sea at the close of the last glacial period. Radiocarbon dating and its position in the oxygen isotope shift suggest that this change may be coincident with the changes found at high latitudes.

Description: Abrupt changes in climatic conditions have been seen at high latitudes in the North Atlantic1 and the Antarctic2,3 at 13 kyr BP. It is important to determine whether this abrupt change was confined to high-latitude regions or whether it was global. Here we present results demonstrating an abrupt change in the rate and character of sedimentation in the South China Sea at the close of the last glacial period. Radiocarbon dating and its position in the oxygen isotope shift suggest that this change may be coincident with the changes found at high latitudes.

Description: Perhaps the most significant event in the Cretaceous record of the carbon isotope composition of carbonate1,2, other than the 1–2.5 ‰ negative shift in the carbon isotope composition of calcareous plankton at the Cretaceous/Tertiary boundary3, is the rapid global positive excursion of ~2 ‰ (13C enrichment) which took place between ~91.5 Myr and 90.3 Myr (late Cenomanian to earliest Turonian (C/T boundary event))1,4,5. This excursion has been attributed to a change in the isotope composition of the marine total dissolved carbon (TDC) reservoir resulting from an increase in rate of burial of 13C-depleted organic carbon, which coincided with a major global rise in sea level5 during the so-called C/T oceanic anoxic event (OAE)6. Here we present new data, from nine localities, which demonstrate that a positive excursion in the carbon isotope composition of organic carbon at or near the C/T boundary7,8 is nearly synchronous with that for carbonate and is widespread throughout the Tethys and Atlantic basins (Fig. 1), as well as in more high-latitude epicontinental seas. The postulated increase in the rate of burial of organic carbon may have had a significant effect on CO2 and O2 concentrations in the oceans and atmosphere, and consequent effects on global climate and sedimentary facies.

Description: In the southern hemisphere, female and young male sperm whales (up to about 39 feet long) are not normally found in higher latitudes than 40° S while large males occur in Antarctic waters1–3; clearly many large bulls must migrate from the breeding areas into colder regions. Evidence of the return of large bulls to lower latitudes rests upon marking them in the Antarctic4 or external infestation by Antarctic Cocconeis or Cyamus 5. Only a single mark5 has been recovered which provides direct evidence for the return north from Antarctic waters. This mark (USSR No. 650203) was fired on December 25, 1967, at 62° 22′ S 26° 25′ E and the whale was killed on May 13, 1968, off Durban. The small size of the male concerned (35 feet at death) makes this record rather surprising although Jonsgård6 did mention that the smallest whales from Antarctic waters were about 35 feet. Marking can provide information on only a small part of the whale population at considerable cost, freshness of the whale restricts the value of infestation as an indicator but the study of food remnants in sperm whale stomachs provides another method without these disadvantages.

Description: The diets of adult Macaroni penguins Eudyptes chrysolophus chrysolophus and Southern rockhopper penguins E. chrysocome chrysocome were analysed quantitatively at Marion Island, southern Indian Ocean, throughout two successive chick-rearing seasons. The diets were broadly similar. Crustaceans were the predominant prey type comprising, overall, 90% by mass and 98% by numbers in Macaroni penguins and 96% by mass and 99% by numbers in rockhopper penguins. Nauticaris marionis was the predominant crustacean eaten by both penguin species in 1983–84, but Euphausia vallentini and Thysanoessa vicina predominated in 1984–85. Themisto gaudichaudii was present in appreciable numbers only in Macaroni penguins. Fish was not found in measurable quantities in either species in 1983–84, but contributed 5% and 4% of the mass of the diet in Macaroni and rockhopper penguins, respectively, when calculated in terms of the original biomass of food ingested. In 1984–85, however, fish comprised 10% and 6% of observed mass and c. 25% and 14% of original biomass ingested in Macaroni and rockhopper penguins, respectively. Pelagic myctophids, predominantly Krefftichthys anderssoni, Protomyctophum tenisoni and P. normani between 0·01 and 8·3 g, were the most commonly identified fish prey, but Macaroni penguins took an appreciable number of Electrona carlsbergi in 1983–84. Cephalopods made up between 1 % and 3% of the diet by mass in both penguin species and between 5% and 13% of original biomass ingested. Predominant cephalopods eaten were Kondakovia longimana and an unidentified octopus species. The relative proportions of each prey type change throughout chick-rearing, with pelagic fish and cephalopods comprising a larger proportion later in the season when the penguins were assumed to be foraging farther from their breeding sites. Dietary segregation of the two species appears to be related to the difference in the timing of the breeding season, which begins three to four weeks earlier in Macaroni penguins.

Description: A fundamental issue in marine science is the identification of the factors controlling biological uptake of CO2, in high-nitrate, low-chlorophyll regions. A recent in situ iron fertilization experiment demonstrated that iron limitation is responsible for low phytoplankton stocks in the equatorial Pacific4. Here we show that flavodoxin, a biochemical marker of iron limitation, can be used to map the degree of iron stress in natural populations. Flavodoxin assays along a 900-km east-west transect in the northeastern subarctic Pacific revealed a pronounced increase in iron stress in the region west of the 135° W meridian. Addition of dissolved iron alleviated this stress. Immunostaining of single cells from the most western station showed that flavodoxin is present specifically within the chloroplasts of diatoms. Our approach provides a rapid means of defining the extent of iron stress in the ocean5 and supports the hypothesis that diatoms are iron stressed in the northeast Pacific.

Description: The germination of spores of the endophytic brown algae Laminariocolax aecidioides and Laminarionema elsbetiae (Ectocarpales sensu lato) on their host Laminaria saccharina was studied using scanning electron microscopy. Zoids were the infective units in both taxa. Despite a large difference in size between spores of the species studied, the initial steps of infection were similar. Zoids settled on the host surface, and during secretion of adhesive material from their anterior end, the spores became elongated to rod-shaped and stood erect on the host. A single germ tube developed at the proximal end and penetrated the intact surface of the host. Sharp edges around the entrance hole and the absence of inward deformation of the host surface around the settled zoids suggest an enzymatic rather than a mechanical penetration mechanism.

Description: Coupled three-dimensional (3-D) physical oceanographic modelling and field sampling programmes were carried out in May 1988 and August 1991 to investigate the potential drift of larval cod (Gadus morhua L.) in the Bornholm Basin of the Baltic Sea. The goals were to predict the transport of cod larvae, thus aiding the identification of physical processes influencing larval retention/dispersal. Numerical simulations were performed using a 3-D eddy-resolving baroclinic model based on the Bryan–Cox–Semtner code adapted for the Baltic Sea. Within the Bornholm Basin, the model was initialized with ground truth data of physical parameters obtained on the research cruises, and all simulations were forced with actual wind data. Outside the basin, generalized hydrographic features of the Baltic Sea were utilized by incorporation of simulated hydrographic fields from previous model runs typical for the time periods considered. Larval drift was simulated either by incorporation of passive drifters, or as the initial horizontal distribution of larvae implemented into the model. Drift model simulations of larval transport agreed relatively well with field observations. The influence of variations in the vertical distribution on a smaller scale, i.e. vertical deviations of ± 6 m from the observed mean centre of mass, on the drift was examined, revealing no significant differences in the drift of larvae depending on their vertical distribution. The different wind forcing during the investigated time periods was linked to a retention situation in May 1988 and to a dispersal situation in August 1991. Finally, observed spatial distribution patterns of 1-group cod based on Baltic Young Fish Surveys (BYFS) were compared with their predicted transport in the larval phase and examined with respect to recruitment.

Description: Mesozooplankton production was estimated by using a new sampling technique and two alternative calculation methods. In essence, production estimates are based on significantly higher abundances. The contribution of juvenile stages to copepod and fish dynamics was generally low, so that the omission of juvenile stages in budgets will result in a small error. The situations reported in this study present a unique food web szenario, which in detail, however, was strongly dependent on methodology. Furthermore, relations between trophic levels were considered with respect to vertical distribution.

Description: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option

Description: Seismic tomography and the isotope geochemistry of Cenozoic volcanic rocks suggest the existence of a large, sheet-like region of upwelling in the upper mantle which extends from the eastern Atlantic Ocean to central Europe and the western Mediterranean. A belt of extension and rifting in the latter two areas appears to lie above the intersection of the centre of the upwelling region with the base of the lithosphere. Lead, strontium and neodymium isotope data for all three regions converge on a restricted composition, inferred to be that of the upwelling mantle.

Description: Gracilaria conferta (Schousboe ex Montagne) J. ct G, Feldmann responded with an oxidative burst and rapid increases in respiration and halogenating activity when agar, agarose, or the agarose degradation products neoagarotetraose and neoagarohexaose were added to the growth medium, In contrast, carrageenan, oligocarrageenans, neoagarobiose, L-galactose, D-galactose, and several other mono- and oligosaccharides did not have any effect, Sixfold increases in respiration were observed 3 min after addition of neoagarohexaose. The response could only be induced in species of the genera Gracilaria and Gracilariopsis. Neoagarohexaose also elicited a release of hydrogen peroxide in less than 15 min, resulting in an immediate increase in algal brominating activity. Bleached thallus tips appeared a few hours after the addition of neoagarohexaose. This effect was dependent on the release of hydrogen peroxide and exposure to light, Exposure to light and oligosaccharide elicitors increased the production of reactive oxygen species, which reached destructive concentrations when both mechanisms were simultaneously active. Concentrations of 0.1 to 3.3 mu M agarose or agars were sufficient to trigger an increase in respiration, an oxidative burst response, and tip bleaching. However, higher concentrations of neoagarohexaose and neoagarotetraose were necessary to elicit the responses, indicating that the alga is more sensitive to oligoagars with degrees of biose-polymerization 〉 3, The extremely short reaction time and high specificity indicate that intermediates of agar degradation are recognized by Gracilaria as messengers when microbial degradation of its cell wall occurs, The physiological responses may represent the early stages of algal defense mechanisms involved in repression of pathogen ingress.

Description: Seismic refraction velocity data from the acoustic basement (called layer 2A) have been compiled for different mid-ocean ridges. The data from post-1970 studies show a strong correlation between velocity and basement age. Importantly, velocities double in less than 10 Myr for all ridges, but for older crust, up to 160 Myr in age, velocities do not increase significantly.

Description: First culture results are presented from four major experiments (lasting up to 478 days) on the commercially important squid species, Loligo forbesi Steenstrup, Details are provided on eggs, hatching, feeding, growth, survival, behaviour and sexual maturation. Best survival during the critical first 75 days was 15%. The hatchlings (up to 4.9mm mantle length, ML) are the largest among the genus Loligo, and the largest squid grown was a male 155mm ML and 124g. First schooling was observed only 40–50 days post-hatching. Spawning was not achieved although males reached maturity, females had maturing ova and mating was observed. The largest giant axon measured was 425μm in diameter (from a female 130mm ML), a size suitable for most biomedical applications. Laboratory data suggest a 2-year life cycle compared to fishery data which suggest a 1-year cycle.

Description: Recent captures of two female giant squid ( Architeuthis ) off southern Australia have provided the first record of a mated female specimen of these almost mythical deepsea creatures. We found sperm packages (spermatophores) embedded within the skin of both ventral arms of the larger of the two specimens. It seems that male giant squids may use their muscular elongate penis to ‘inject’ sperm packages under pressure directly into the arms of females.

Description: Two species of the family Bothidae (lefteye flounders), Mancopsetta maculata metadata and M. milfordi occur in the south‐west Atlantic but are caught rarely by commercial bottom trawlers. Little is therefore known about their general biology from this area. A total of 251 M. maculata and 276 M. milfordi were sampled during deep‐water exploratory fishing conducted in November 1994 within the Falkland Islands Interim and Outer Conservation Zones, at depths of 400‐1000 m, using standard commercial bottom trawling gear. The two species were found to have similar geographical distributions between 48.30′‐53.30'S and 55°‐62° W and were often obtained at the same stations in depths of 400‐900 m on the continental slope. Mancopsetta maculata maculata showed a uni‐modal cohort structure with a modal length at the 29‐cm total length size‐class. Males of M. m. maculata outnumbered females in a ratio of 3.5 : 1. Mancopsetta milfordi showed a tri‐modal length distribution, the main mode at the 37‐cm total length size‐class, with females outnumbering males in a ratio of 1.1 : 1. Length‐weight relationships and length‐at‐age information are presented for the two species. Diet was determined from the analysis of stomach contents and, although the major prey type for both species consisted of crustaceans, the morid fish Austrophycis marginata also formed an important part of the diet of M. milfordi. Key words: Mancopsetta maculata maculata; Mancopsetta milfordi; distribution; south‐west Atlantic; size; diet.

Description: Records of demersal deep‐sea fish assemblages in waters around the Falkland Islands (Patagonian shelf area) are rare. Twenty deep‐water stations to the east and south of the Falkland Islands were sampled by commercial bottom trawl deployed in upper, middle and lower benthopelagic zones (depth range of approximately 500‐1000 m). Forty‐one species (22 families) of teleost fish were recorded, 10 species (two families) of elasmobranch and one species of agnathan. Different assemblages of fish were found to characterize each depth zone (e.g. Moridae in deeper waters, Bothidae and Rajidae in shallower waters), with diversity being greatest in the mid‐zone and biomass greatest in the upper and lower zones. Some species occurred in all zones but showed depth‐related abundance. Four species, namely the grenadiers Macrourus carinutus and Coelorhynchus fasciatus, the southern blue whiting Micromesistius australis, and the Patagonian toothfish Dissostichus eleginoides, accounted for 85% by weight of all fish caught. Quantitative sampling of selected species revealed depth‐related variations in their population structure. Length‐frequency analyses are presented for M. carinatus and D. eleginoides and show a tendency for larger individuals to inhabit deeper water. Discard rates from the commercial catch were sometimes high, particularly for the smaller species, raising concerns about the impact of a fishery on by‐catch species. The potential for deep‐sea fisheries in Falkland waters is discussed and further studies are suggested in the light of developing oil, gas and fishing industries. The presence of some invertebrate taxa is recorded.

Description: This paper presents quantitative analyses at the community level of the spatial dispersion of 44 species of pelagic birds in the South Atlantic Ocean. I have examined the extent to which assemblages of pelagic bird species are influenced by the combined influences of the abundances of other species and the physical structure of the pelagic environment. Results are based upon strip transects collected from oceanographic research vessels during the four consecutive austral summers of 1982–1986. The distributions of most seabird species were statistically independent of the distributions of other species. Species assemblages, however, did occur and were correlated with the physical structure of the ocean. The study area was divided into four zones, each defined by a distinctive assemblage of birds. Physical oceanography proved to be important in determining the species composition of each zone. These relationships were apparent despite the potentially confounding influence of large numbers of immatures and non‐breeding adults.

Description: Allocation processes play a central role in life history theories. Yet very few studies have been carried out on the link between foraging and life history in the context of allocation of resources. Here we report a study examining the relationship between foraging and allocation of resources in the Wandering Albatross Diomedea exulans of Crozet Islands. We simultaneously studied individual foraging strategies at sea and differential allocation to reproduction and storage by measuring the energy supplied to chicks and the variation of body mass of the adult. Satellite tracking and continuous monitoring of nest attendance by adults showed that while rearing a chick Wandering Albatrosses have two specific alternative foraging strategies. They either forage in short trips, short in duration and close to the colony over the southeastern slope of the peri‐insular shelf, or in long trips far from the colony in the oceanic waters north of Crozet. On average, birds made five successive short trips before making a long trip. Chicks received a meal every 1.8 d and were fed with fresh prey, 72% squid and 24% fish, and a liquid fraction composed of oil and water. During short trips birds appear to rely to a great extent on Moroteuthis ingens, a squid species probably available in large numbers at the southeastern edge of the Crozet shelf. The measure of energy flows indicates that 74% of the energy delivered to the chick comes from short trips, whereas only 33.8% of the total energy is gained at sea during these trips. Males spent a greater proportion of their time foraging in short trips than females, and consequently chicks received 61.3% of their meals from males and 38.7% from females. Adult birds tended to lose mass after short trips and to lose more mass with increased duration of short trips, whereas they gained mass after long trips. They initiated long trips when their body mass was low. Although Wandering Albatrosses are able to provision their chicks at a rapid rate because of the proximity of an abundant resource, birds still have to forage far from the colony to restore their body condition. Estimates of energy yield explain this paradox, as they suggest that the rate at which prey is caught during short trips in shallow waters is half that during long trips in oceanic waters. The significance of the twofold foraging strategy in relation to food availability and foraging efficiency is discussed.

Description: There was a seasonal biomodality in the distribution of breeding activities of King Penguins Aptenodytes patagonicus, studied from 1991 to 1994 at South Georgia, with peaks of courtship and egg-laying 2-3 months apart. The late peak was of birds that bred successfully the previous year, whereas the early peak was of birds that had failed. Successful birds were delayed because the median time for a complete breeding cycle, including moult, was 〉 14 month. Although most birds made a breeding attempt each year, none bred successfully in two consecutive seasons. Hence, in practice the cycle was biennial. The egg-laying period spanned four months but only pairs that laid within the first quarter of this period were successful. Parental quality, rather than laying date, strongly influenced the outcome of first quarter breeding attempts. No late breeding attempt was successful and why they are undertaken is unclear. At least they posed no measurable cost, either by delaying subsequent breeding or by increasing mortality; this may be important for balancing the low benefit. After the over-wintering fast the chick could be fledged by a single parent; but no sex-specific difference in invested time in the chick near to fledge was observed.

Description: When King Penguin Aptenodytes patagonicus males arrive on the breeding grounds to start courtship, their energy reserves must sustain them during a fast lasting about five weeks, including the first incubation shift. If the female is delayed in relieving the incubating male, he must make a state-dependent decision of how long to wait until abandoning the egg (i.e. breeding failure). This is ultimately a life-history trade-off between current reproduction and future survival, and includes consideration of the size of his remaining energy reserves and his ability to replenish exhausted body reserves (foraging skills). Experienced males that abandoned the egg weighed significantly less (9.49 kg) at departure than relieved males (10.43 kg), but inexperienced males abandoned the egg at a nearly significantly higher body mass (10.27 kg) than experienced males. I conclude that experienced birds can compensate for lower body reserves by being more proficient foragers.

Description: Observations of small schools of squids in captivity suggested that dominance relationships among males were based upon major differences in the frequency or duration of their agonistic behavior, but staged contests showed few differences. During staged contests, squids exhibited up to 21 separate behaviors. Some contests included a complex array of visual signals and side‐by‐side posturing (Lateral Display) followed by physical contact during Fin beating. There was behavioral variability and step‐wise escalation during the contests: squids performed either 1. long sequences of visual signaling followed by Chasing and Fleeing; or 2. short sequences of visual signaling followed by physical Fin beating and ending with Chasing and Fleeing. Size influenced outcome in all contests; larger males were more likely to win the contest. Size had no effect on contest duration, but contest duration was shorter when resource value was high, especially when a male established temporary ownership of a female. We speculate that when the perceived resource value is high, male squids are more likely to engage in a shorter yet riskier fighting tactic.

Description: 1. Monthly series of abundance indexes for the English Channel squid stock, based on fishery statistics of the United Kingdom (1980–93) and France (1986–96), were compared with water temperature data. The two objectives of the study were to test empirical predictive models and to analyse the stock–environment relationship at various time scales; both correlation and time-series statistical techniques were applied. Sea surface temperature (SST) showed inter-annual fluctuations and month-to-month auto-correlation in addition to the annual cycle. 2. Trends in squid landings and temperature at the annual scale were found to be related, whatever the statistical method used (moving averages, cumulative functions or regression using averaged data). 3. Variable selection applied in a ‘multi-month’ model suggested that fishing season indexes could be predicted from temperatures observed in the previous winter. The link between mild winter conditions and cohort success in winter/spring spawning species suggested that early life survival (and/or growth) was involved. This empirical model is a first step in the development of environment-predicted recruitment indexes useful for management advice. 4. Seasonal decomposition was performed on both the squid resource data and SST data in search of short-term relationships. In spite of the flexibility of the loliginid life-cycle, no significant relationship was found between squid seasonally adjusted indexes and temperature anomalies in the previous months. This underlined the conclusion that temperature effect on cohort success was not constant throughout the year.

Description: A 3 year study of the diets of breeding royal Eudyptes schlegeli and rockhopper E. chrysocome penguins was carried out at two nearby colonies on Macquarie Island. Diets of both species were dominated by euphausiids and myctophid fish, in particular Euphausia vallentini and Krefftichthys anderssoni. Prey items were those found in the region of the Polar Frontal Zone, confirming the importance of this zone to these penguins. Diets of both species before hatching of the chicks were variable between years, and differences in quantity of food brought ashore and degree of digestion of prey suggested inter-annual variation in distribution of prey resources. No dietary differences were detected in either penguin species across the breeding season, which reflected variability in diet at all stages, indicating that individual penguins foraged in separate areas. Significant differences between the two species were found, royal penguins consuming more myctophid fish and rockhopper penguins consuming more euphausiids. Differences were also found in the size class of prey items taken and the degree of digestion of food by both penguin species, indicating that prey were taken from different sectors of the ocean. It is concluded that the overlap in diet is small in individuals from these two spatially close colonies and, contrary to previous studies, indicates a separation in the resources used by both species. The contrast with previous studies is most likely a reflection of the different methods used to assess overlap and, to a lesser extent, the years and colonies in which the comparisons were made.

Description: Mastigophora brevipinnis Owen, 1856, is a ‘fossil teuthid’ presently considered to be a member of the coleoid cephalopod Suborder Loligosepiina Jeletzky, which in turn has been placed by various authors in or near the Vampyromorpha Grimpe. Recent morphological and biochemical analyses indicate that vampyromorphs are more closely related to the Octopoda than to the Decapodiformes. Fossils of Mastigophora from the Oxford Clay (Jurassic: Callovian) show soft-tissue preservation and evidence of arm crown specialization. Some of these fossils have up to eight short, thick arms with circular sucker-like structures and filiform distal extensions, plus what appear to be the bases of two thinner ventrolateral arms. The latter lack proximal suckers and curve medially to insert into the arm crown, similar to the tentacles that are the modified ventrolateral arms of living squids and cuttlefishes. This suggests that the thinner structures were decapod-like tentacles. If Mastigophora had tentacles homologous with those of modern decapods, then it was a decapod, because this synapomorphy defines the Decapodiformes. This indication of decapod affinities for Mastigophora brings into question the relationships of the other ‘fossil teuthids’. The inferred relationship of the Loligosepiina, including Mastigophora, with the Vampyromorpha, based largely on similarities of gladius morphology with that of living Vampyroteuthis, may reflect shared plesiomorphic characters.

Description: The filaria Litomosoides sigmodontis, which develops a patent infection in BALB/c mice, was used to determine the fate of a challenge inoculum following immunization of mice with irradiation attenuated infective larvae (3 subcutaneous inoculations at weekly intervals with 25 L3 irradiated at 60 krad, and challenge with 25 L3 two weeks after the final immunization). The adult worm burden of vaccinated mice was reduced to 50% of that of controls although the pattern of larval migration and microfilaraemia were not affected. Necropsies showed that the increased killing of the filariae of the challenge inoculum occurred at the L3 stage within the first 2 days of challenge. This result draws attention on the protective mechanisms operating very early and probably in the subcutaneous region.

Description: Stomach contents were analyzed from 85 Dall's porpoises, Phocoenoides dalli, taken in the southern Sea of Okhotsk during the summer of 1988. Thirteen species of fish and five species of cephalopods were identified. Fishes comprising 9 families were predominant and made up 79.9% of the total number of prey, with an overall occurrence in the stomachs of 100%. Three families of cephalopods made up 20.1% of the total number of prey ingested, with an overall occurrence of 74%. The Japanese pilchard, Sardinops sagax melanostictus, was the primary prey and represented 72.0% of the total prey in 97.3% of the stomachs examined. The gonatid squid, Berryteuthis magister, ranked second and made up 16.9% of the total prey in 61.6% of the stomachs. Walleye pollock, Theragra chalcogramma, was the third most abundant prey item consumed and represented 6.0% of the total, with an occurrence of 53.4%. Composition of the sample by the calculated total mass and caloric intake supports the numeric findings on the relative importance of the three major prey species to the DaIl's porpoise diet. The Japanese pilchard was clearly dominant using these indices and constituted 65.4% of the total mass and 80.7% of the caloric intake. Berryteuthis magister made up 26.8% of the mass and 15.5% of the caloric intake. Walleye pollock contributed the least to the diet with 7.9% of the total mass and 3.8% of the caloric intake. Volumetric data indicate that porpoises are feeding heavily on Japanese pilchard throughout the daylight hours. Berryteuthis magister was probably fed upon in the late night or early morning hours. Occurrence of both Dall's porpoise and Japanese pilchard in the coastal waters of the southern Sea of Okhotsk is seasonal. The summer movements of Dall's porpoise into this region may be related to the seasonal migration and abundance of the Japanese pilchard.

Description: Three time series of pelagic bird abundance collected in disparate portions of the California Current reveal a 90% decline in Sooty Shearwater (Puffinus griseus) abundance between 1987 and 1994. This decline is negatively correlated with a concurrent rise in sea‐surface temperatures; Sooty Shearwaters have declined while sea temperatures have risen. There is a nine‐month lag in the response by shearwaters to changing temperatures. The geographical scale of our study demonstrates that the decline of Sooty Shearwaters is not a localized phenomenon, nor can it be ascribed to a short‐term distributional shift. The Sooty Shearwater is the numerically dominant species of the California Current System (CCS) in summer (austral winter), with an estimated population in the late 1970s of 5 million individuals. If the observed warming of the waters of the California Current System is an irreversible manifestation of a changing global climate, then the impact upon Sooty Shearwater populations seems likely to be profound.

Description: We have determined the centroid depths and source mechanisms of 12 large earthquakes on transform faults of the northern Mid-Atlantic Ridge from an inversion of long-period body waveforms. The earthquakes occurred on the Gibbs, Oceanographer, Hayes, Kane, 15°20′, and Vema transforms. We have also estimated the depth extent of faulting during each earthquake from the centroid depth and the fault width. For five of the transforms, earthquake centroid depths lie in the range 7–10 km beneath the seafloor, and the maximum depth of seismic faulting is 14–20 km. On the basis of a comparison with a simple thermal model for transform faults, this maximum depth of seismic behavior corresponds to a nominal temperature of 900° ± 100°C. In contrast, the nominal temperature limiting the maximum depth of faulting during oceanic intraplate earthquakes with strike-slip mechanisms is 700° ± 100°C. The difference in these limiting temperatures may be attributed to the different strain rates characterizing intraplate and transform fault environments. Three large earthquakes on the 15°20′ transform have shallower centroid depths of 4–5 km and a maximum depth of seismic faulting of 10 km, corresponding to a limiting temperature of 600°C. The shallower extent of seismic behavior along the 15°20′ transform may be related to a recent episode of extension across the transform associated with the northward migration of the triple junction among North American, South American, and African plates to its present position near the transform. The source mechanisms for all events in this study display the strike-slip motion expected for transform fault earthquakes; slip vector azimuths agree to within 2°–3° of the local strike of the zone of active faulting. The only anomalies in mechanism were for two earthquakes near the western end of the Vema transform which occurred on significantly nonvertical fault planes. Secondary faulting, occurring either precursory to or near the end of the main episode of strike-slip rupture, was observed for five of the 12 earthquakes. For three events the secondary faulting was characterized by reverse motion on fault planes striking oblique to the trend of the transform. In all three cases the site of secondary reverse faulting is near a compressional jog in the current trace of the active transform fault zone. We find no evidence to support the conclusions of Engeln, Wiens, and Stein that oceanic transform faults in general are either hotter than expected from simple thermal models or weaker than normal oceanic lithosphere.

Description: Within the Australian-Antarctic Discordance (AAD), a boundary exists between isotopically defined “Pacific-type” and “Indian-type” mid-ocean ridge basalt (MORB) erupted along the Southeast Indian Ridge (SEIR). This boundary has migrated westward beneath the easternmost AAD spreading segment at a minimum rate of 25 mm/yr since 4 Ma; however, its long-term history remains a matter of speculation. To determine if Pacific-type upper mantle has migrated westward beneath the eastern Indian Ocean basin as Australia and Antarctica drifted apart during the last 70 m.y., we present new Sr-Nd-Pb isotope data, combined with trace element and 40Ar-39Ar radiometric age determinations, for samples from Legs 28 and 29 of the Deep Sea Drilling Project (DSDP). Basaltic basement at these DSDP sites provides a record of their upper mantle source composition and shows regional variations consistent with upper mantle flow in this region. East of the South Tasman Rise, all DSDP basalts have 87Sr/86Sr (0.7025–0.7029) and 206Pb/204Pb (18.80–19.48) ratios typical of Pacific-type MORB indicating that Pacific-type upper mantle existed east of the Australian-Antarctic continental margin and beneath the Tasman Sea during the early stages of seafloor spreading in this region. Basalts from DSDP sites west of the AAD have high 87Sr/86Sr (0.7030–0.7035), low 206Pb/204Pb (17.99–18.10) and trace element characteristics typical of present day Indian-type SEIR MORB. Between these two regions, DSDP basalts recovered along the western margin of the South Tasman Rise have isotopic characteristics that are, in one case consistent with an Indian-type MORB source (Site 280A) and, in the second case, transitional between Pacific-type and Indian-type mantle sources. The occurrence of seafloor basalts with transitional or Indian-type isotopic characteristics well to the east of the present Indian-Pacific MORB isotopic boundary within the AAD strongly implies that Pacific-type upper mantle has migrated westward into the region since the South Tasman Rise separated from Antarctica circa 40 Ma.

Description: Microsatellite DNA markers were applied for the first time in a population genetic study of a cephalopod and compared with previous estimates of genetic differentiation obtained using allozyme and mitochondrial DNA (mtDNA) markers. Levels of genetic variation detected with microsatellites were much higher than found with previous markers (mean number of alleles per locus=10.6, mean expected heterozygosity (HE)=0.79; allozyme HE=0.08; mtDNA restriction fragment length polymorphism (RFLP) HE=0.16). In agreement with previous studies, microsatellites demonstrated genetic uniformity across the population occupying the European shelf seas of the North East Atlantic, and extreme genetic differentiation of the Azores population (RST/FST=0.252/0.245; allozyme FST=0.536; mtDNA FST=0.789). In contrast to other markers, microsatellites detected more subtle, and significant, levels of differentiation between the populations of the North East Atlantic offshore banks (Rockall and Faroes) and the shelf population (RST=0.048 and 0.057). Breakdown of extensive gene flow among these populations is indicated, with hydrographic (water depth) and hydrodynamic (isolating current regimes) factors suggested as possible barriers to migration. The demonstration of genetic subdivision in an abundant, highly mobile marine invertebrate has implications for the interpretation of dispersal and population dynamics, and consequent management, of such a commercially exploited species. Relative levels of differentiation indicated by the three different marker systems, and the use of measures of differentiation (assuming different mutation models), are discussed.

Description: The diet of the white‐chinned petrel at Bird Island, South Georgia was studied during chickrearing in 1986 by quantitative analysis (by weight, frequency of occurrence and number of individuals) of regurgitated or lavaged adult stomach contents. Antarctic krill comprised over 90% of prey items and formed 47% of the diet by weight; fish and squid occurred in 67% and 35% of samples and formed 33% and 19% of the diet by weight, respectively. Decapods, amphipods and salps occurred in a few samples. The fish were mainly lanternfish (Myctophidae) of eight species (chiefly Electrona and Gymnoscopelus, forming 80% by number and 52% by mass of fish prey) and the nototheniid Patagonotothen guntheri (14% by number and 35% by mass). Of squid taken, the ommastrephid Martialia hyadesi comprised 57% by number and 52% by mass and the gonatid Gonatus antarcticus 14% by number and 42% by mass. These dietary data confirm white‐chinned petrel as the most important avian consumer of fish and squid at South Georgia (and the third most important consumer of krill). In 1986 the nototheniid fish were probably obtained via commercial fishing operations but the myctophids and squid were probably live‐caught, most likely at night. Meal size increased rapidly until chicks were three weeks old and then remained constant until the chicks were within 10 days of fledging, when it decreased. Meal delivery rate was high (one per day) for young chicks (1–10 days old) and thereafter fluctuated between 0.56 and 0.88 meals per day until close to fledging, when it was halved. These provisioning rates, and the proportion of krill in the diet, are higher than those recorded previously at South Georgia and Indian Ocean sites, probably reflecting high local availability of krill at South Georgia in 1986. In many respects, white‐chinned petrels at South Georgia are intermediate ecologically between prions and albatrosses, although specialized in their extensive consumption of myctophids. Because krill and all the main fish prey are currently the targets of substantial commercial fishing and the main squid prey (Martialia) is a potential target, the ecological role and status of white‐chinned petrels are of additional importance.

Description: Models of the giant squid (Architeuthis spp.) are probably unique in natural history exhibition: they are representations of a giant living animal that has never been seen in a healthy state by a human being. Since its discovery in the mid‐nineteenth century, the giant squid has remained one of the world's great zoological mysteries. In the attempt to introduce this fabulous creature, museums around the world have resorted to life‐sized models. Yale teuthologist A.E. Verrill was responsible for the first such models in 1882; then Ward's Natural Science Establishment in Rochester, New York, manufactured and sold them. In this century, various museums (and one zoo) have made their own models of these ten‐armed monsters of the deep. Their disparate attempts to re‐create Architeuthis for the museum public represent one of the most intriguing case histories in the annals of museum exhibition.

Description: Maturing females of the octopod Japetella diaphana (Hoyle) develop a luminous oral ring. Studies of specimens of different size show that this structure develops from a muscular ring which undergoes great cellular proliferation, associated with gradual degeneration of the original muscle. The light‐producing cells (photocytes) have a relatively uniform cytoplasm whose most characteristic components are small mitochondria, granular aggregates and microtubular or microfibrillar bundles. It is concluded that the original muscle tissue is not transformed directly into luminous tissue. Possible uses of the luminescence are discussed, based on the postures adopted by live specimens in shipboard aquaria.