ALBERT

Description: Skin and hair samples of harbour seals (Phoca vitulina) found dead along the west coast of northern Germany in 1988 were analysed for total mercury, cadmium and lead. Cadmium and lead concentrations were below the detection limit in most skin samples. The mercury content of the hair (median: 23.1 μg g−1 wet wt) was several magnitudes higher than the mercury content of the skin (0.27 μg g−1 wet wt). Mercury concentrations in hair samples were significantly higher than lead concentrations (0.54 μg g−1 wet wt), which significantly exceeded cadmium levels (0.09 μg g−1 wet wt). Female seals revealed lower cadmium concentrations in the hair than male seals. Accumulations of metals with age were observed for cadmium and lead in hair samples and for mercury in skin samples of male seals. A connection between metal accumulation and pigmentation or rather moult was clearly recognizable.

Description: The spreading of Mediterranean Water (MW) released through the Straits of Gibraltar is studied with hydrographic data, oxygen, nutrients and for the first time with chlorofluoromethane (CFM, compounds F11 and F12) distributions along seven sections in the Gulf of Cadiz, and with measurements in the Western Alboran Sea and west of the Gulf. The properties of MW entering the Gulf are deduced from CFM-salinity correlations east and west of the Straits as well as from property-depth profiles in the Western Alboran Sea. At the time of the survey, the outflow originated from depths above the salinity maximum of the Intermediate Water in the Alboran Sea. It turned out that the F11/F12 ratio of the outflow is equal to the ratios found in the Atlantic water in the Gulf of Cadiz; thus the ratio carries no time information in the region. A model is developed to describe mixing of the MW undercurrent with overlying North Atlantic Central Water (NACW) from different depths. The contribution of each layer to the mixing is parameterized by a weighting factor, which has to satisfy the balances of potential temperature (θ), CFMs, oxygen and nutrients in the MW undercurrent. It is shown that entrainment of water from shallower depths into the undercurrent is important near the Iberian Continental Shelf. Farther west and south, the undercurrent mainly mixes with water from near the salinity minimum of the NACW. For regions where the undercurrent has left the bottom, additional mixing with North Atlantic Deep Water (NADW) has to be taken into account. The percentage of MW in the undercurrent decreases from 76% hear the Straits to about 34% at 7°30′W for the lower core (MI) and about 22–24% for the upper core (Mu). Assuming an outflow of undiluted MW through the Straits of 1.0 Sv, the transport of the undercurrent can be calculated by determining an average dilution factor for each section. The undercurrent transports 2.0 Sv just west of the Straits and 3.6 Sv leave the Gulf of Cadiz. At 36°N, 9°54′W, a meddy with unusually high temperatures and salinities below 500 m was found, covering the density range for both cores, Mu and Ml. From the θ−S characteristics and the evaluated mixing scheme of the meddy it appears to have formed near 7°W in the Gulf, a region up to now not proposed in the literature, and moved westward without much further mixing.

Description: In April 1990, 488 marine fish belonging to 30 species from central Phillipine waters were examined for flesh parasitic infections that may affect their consumability. One species of hemirhamphids and 3 species of belonids harboured plerocercoids of Otobothrium penetrans Linton, 1907 (Proceedings of the U.S. National Museum33, 85–126). This is the first record of this parasite from Pacific fish species. The highest intensity of infection found was 8 in Tylosurus crocodilus. Most of the larvae were located between the dorsal spines of the vertebral column, only 32% were found in the fillets. Based on the present material we give a description of the plerocercoid stage of the species using scanning electron microscopy of the armature and morphometrical measurements. Comparison to results from earlier findings of O. penetrons by Linton (1907; 1924, Proceedings of the U.S. National Museum64, 1–114) and to O. kurisi by Shields (1985, International Journal for Parasitology15: 635–643) lead to the conclusion that the latter species is a synonym for O. penetrans.

Description: Work on the life histories of common antarctic benthic marine invertebrates over the past several decades demands a revision of several widely held paradigms. First, contrary to expectations derived from work on temperate species, there is little or no evidence for temperature adaptation with respect to reproduction (gametogenesis), devel? opment, and growth. It remains to be determined whether the slow rates of these processes reflect some inherent inability to adapt to low temperatures, or are a response to features of the antarctic marine environment not directly related to low temperature, such as low food resources. Secondly, contrary to the widely accepted opinion designated as "Thor- son's rule," pelagic development is common in many groups of shallow-water marine invertebrates. In fact in some groups, such as asteroids, pelagic development is as prevalent in McMurdo Sound, the southern-most open-water marine environment in the world, as in central California. In other taxonomic groups, especially gastropods, there does seem to be a genuine trend toward non-pelagic development from tropical to antarctic latitudes. Although this trend has been predicted by theoretical models, its underlying causes appear to be group specific rather than general. Thirdly, pelagic lecithotrophic development, often considered to be of negligible importance, occurs in many shallow-water antarctic marine macroinvertebrates. Pelagic lecithotrophy may be an adaptation to a combination of poor food conditions in antarctic waters most ofthe year and slow rates of development. Nevertheless, some of the most abundant and widespread antarctic marine invertebrates have pelagic planktotrophic larvae that take very long times to complete development to metamorphosis. These species are particularly prevalent in productive regions of shallow water (〈 30 m), which are frequently disturbed by anchor ice formation, and the production of numerous pelagic planktotrophic larvae may represent a strategy for colonization. Although planktotrophic larvae tend to be seasonal in occurrence, their production is not linked particularly closely to the mid-summer pulse of phytoplankton production. These larvae show no evidence of starvation, even during times when phytoplankton abundance is very low, and they may depend on unusual sources of food, such as bacteria. How they escape the selective conditions that apparently led to a predominance of non-feeding modes of development in antarctic marine invertebrates remains as a major challenge for antarctic marine biology.

Description: Nine large box cores collected in the western Greenland-Iceland-Norwegian (GIN) Sea were analyzed for calcium carbonate content and coarse fraction components. Stratigraphic control is based on oxygen isotope records performed on four of the cores. All cores were correlated using oxygen and carbon isotope data, fluctuations in calcium carbonate content, coarse terrigenous particle content and volcanic ash beds. Glacial and interglacial cycles are documented by a number of terrigenous particle events and differentiated calcium carbonate production which can be correlated to major paleoceanographic and paleoclimatic shifts. In the older core sections, extensive deposition of ice-rafted detritus (IRD) persisted until about oxygen isotope stage 9 and document a relatively stable environment in this area, strongly influenced by cold surface water masses. The following interval was characterized by variations in the general surface water circulation pattern, although high amounts of IRD are still present in Iceland Sea sediments. Pronounced shifts in terrigenous input and pelagic carbonate records were identified close to the oxygen isotope stage Full-size image (〈1 K) and Full-size image (〈1 K) boundaries, indicating massive melting of icebergs in the western GIN Sea. These enormous inputs of debris were followed by an increase in calcium carbonate production caused by maximum intrusion of warm Atlantic surface waters. Relatively high calcium carbonate contents also show that only little dilution by fine-grained material and a minimum of ice melting occurred during these warm phases. During oxygen isotope stage 5, conditions were more uniform indicating a less pronounced westward penetration of Atlantic waters as compared to the Holocene. The last glacial (stages 4-2) is characterized by the occurrence of “Heinrich”-like events, although high IRD contents were present throughout this interval. A distinct contrast between the northernmost cores and the cores in the south is indicative of a rather strong westward penetration of Atlantic water in the north and of an area dominated by cold water east of the Kolbeinsey Ridge during the Holocene. However, conditions west of Jan Mayen seem to have remained constantly dominated by cold surface waters throughout the whole time investigated.

Description: The inner Scotian Shelf off the Eastern Shore of Nova Scotia forms an irregular surface that extends some 25–30 km seaward of the present coastline to water depths of about 100 m where it drops off into Emerald Basin. The distribution of Late Quaternary deposits is highly variable both along and across the shelf. These sediments preserve a record of Late Wisconsinan glaciation, ice recession, and late- and post-glacial changes of relative sea level. Glaciomarine deposits occur in a valley complex extending seaward from Halifax Harbour. East of Halifax, we observe a three-part zonation across the inner shelf. The innermost zone extends to water depths of about 50 m. It is characterized by acoustic basement (Meguma Group metasediments), either outcropping or overlain by acoustically unstratified deposits, interpreted as glacial diamict, and by a unit interpreted as stratified outwash. These units are overlain by stratified valleyfill deposits representing Holocene lacustrine and estuarine facies, which have been sampled in a number of cores. Much of the inner shelf is covered by a thin veneer of sand and gravel, generally less than 1 m thick. Further seaward, the sea floor is an erosional unconformity that truncates acoustic units interpreted as glacial diamict and stratified drift. The stratified estuarine deposits found in the inner zone appear to be absent here, but thin patches of transgressive lag deposits occur throughout the area. The outer part of the inner shelf is dominated by outcrop of acoustic basement, with very limited surficial sediment cover. This zone of rugged outcrop occupies half or more of the inner shelf width over much of the study area. The extensive outcrop is attributed to a combination of glacial and/or glaciofluvial erosion, limited recessional deposition, and reworking of any remaining sediment cover by energetic long-period surface gravity waves under lower postglacial sea levels. Seaward of the outcrop zone, there is a transitional area between the inner shelf and Emerald Basin. This zone is characterized by high relief, with exposures of acoustic basement rising up to 60 m above intervening depressions. The depressions are partially filled by stratified glaciomarine and marine deposits up to 55 m thick. Lateral transitions between stratified and unstratified facies along a morainal ridge in northern Emerald Basin suggest the presence of a partially grounded floating ice margin in this area. Late-glacial relative sea level changes remain poorly defined. Several lines of evidence suggest high relative sea level early in the process of glacial recession from the inner shelf, followed by a rapid drop resulting from glacio-isostatic rebound. Samples of estuarine and salt-marsh deposits collected in cores from the inner part of the inner shelf provide evidence of Holocene marine transgression from below −40 m at 11,000 years BP, continuing to the present.

Description: Horizontal distribution of myctophid fishes were studied from two transects in the Arabian Sea in 1987. Species numbers exhibited a south-north decline in diversity, with only half of the fish taxa occupying the northeastern region. Diaphus arabicus was the dominant species both in the south and north. All recorded myctophid fish species migrate in a diel pattern, residing during daytime at depths of extremely low oxygen levels (〈0.1 ml O2 1−1) and foraging in the oxygen-rich surface layer at night. Feeding patterns were determined for the six most abundant myctophid species. All species appeared to be opportunistic predators that prey on a comparatively narrow food spectrum consisting principally of small to medium sized copepods. Numerically, non-calanoid copepods (with Oncaea conifera and O. venusta dominating) made up to 70% of the diet of D. arabicus and Bolinichthys longipes. Of the 26 calanoid copepod species identified from the six myctophid taxa, the genera Euchaeta, Pleuromamma and Candacia generally dominated in the stomachs, with P. indica constituting between 21 and 95% (by numbers) of the calanoid copepod prey.

Description: Particulate fluxes of aluminium, cadmium, cobalt, copper, iron, manganese, nickel, phosphorus, lead, vanadium and zinc in the northeast subtropical Atlantic Ocean have been determined from sediment trap samples collected between 1 December 1986 and 30 April 1987 at 1020 and 4120 m below the ocean surface. The fluxes of most elements (except Cd and P) show small variations between the different layers, and are closely associated with the vertical transport of aluminium. Elemental composition and flux rates suggest that aerosol loadings from northeast trade winds are the major contributor of these elements to depositing material. Extremely low fluxes of copper, lead and zinc also indicate that anthropogenic perturbations are of insignificant importance in this region.

Description: Within the framework of the JGOFS Pilot Study in 1989 mesozooplankton (0.2–20 mm) was sampled by means of a Hydro-Bios multinet in five depth strata (0–25, 25–50, 50–100, 100–200, 200–500 m) during four Lagrangian drift experiments of 8–14 days' duration at 18, 33, 46 and 58°N, to follow the seasonal progress of the phytoplankton spring bloom development in the northeast Atlantic. Mesozooplankton standing stock, measured as dry weight and ash-free dry weight, increased by a factor of about 6 from 18 to 58°N. Day/night differences amounted to 10–20% of the average and were—with one exception at 18°N—not statistically significant. Using the data on weight-specific respiration rates measured by colleagues on the same cruise, the ingestion rates and potential community grazing of mesozooplankton on phytoplankton within the upper 100 m of the water column were calculated. During all four drift experiments, quasi-steady-state conditions were observed in phyto- and zooplankton standing stock, primary production and daily sedimentation at 100 m depth. The maximum potential grazing rate by mesozooplankton accounted for about half of the daily primary production. Since sedimentation of fresh phytoplankton was negligible, it is concluded that the grazing pressure exercised by mesozooplankton together with micro- and nanozooplankton was responsible for keeping the phytoplankton standing stock at a more or less constant level during the investigated spring bloom in the four areas. Particle flux was thus dominated by zooplankton faecal material.

Description: Accurate congener-specific determination of chlorobiphenyl congeners (all 209 congeners) is finally possible with the use of multidimensional gas chromatography-electron-capture detection techniques. The effectiveness of this technique for environmental analyses is enhanced by ultraclean laboratory practices, non-destructive extraction and clean-up steps and the use of low-volume, high-efficiency HPLC separation for various classes of organic contaminants. In the light of these new developments conventional procedures for chlorobiphenyl analysis are evaluated.

Description: The productivity regime and size structure of phytoplankton are described for three different epipelagic systems in the Arabian Sea during the inter-monsoon period in spring 1987: (1) the coast of Oman; (2) the central Arabian Sea; and (3) the shelf off Pakistan. These results are related to the functioning of the specific ecosystem. Off the coast of Oman, the transition from a surface maximum of autotrophic biomass and production to a more oligotrophic system, with a chlorophyll subsurface maximum, was observed. Concomitantly, the size spectrum changed towards a higher significance of picoplankton. In the central Arabian Sea, a typical oligotrophic system with a pronounced subsurface maximum of autotrophic biomass and primary production was encountered. Here, the epipelagic system could be divided into two distinct sub-systems: the surface layer “regenerated” production, the predominance of picophytoplankton and minor losses due to sedimentation, thus a “closed” system; and the subsurface maximum layer at the nutricline characterized by higher sedimentation losses and more diatoms. Both sub-systems showed about the same productivity, the turnover in the surface layer having been much greater than in the subsurface maximum. The system on the shelf off Pakistan is seen as a decay stage of the open ocean system when water from offshore is transported onto the shelf during the onset of monsoon winds.

Description: Helium (RA = 3.0 to 5.6) and carbon (δ13C from −7.2 to −3.4‰) isotopic compositions, and relative CO2, CH4, N2, He and Ar contents of CO2-rich gases from Lakes Nyos and Monoun, Cameroon; Laacher See, Germany; Dieng Volcanic Plateau, Indonesia, and a well at Mt. Gambier, Australia, point to a common, essentially magmatic origin. Absorption of the original magmatic gases into deeply circulating groundwater and equilibration of the resulting solutions with crustal rock at temperatures of about 300°C fix CO2 and CH4 contents. On further rise, the solutions start to boil separating gas-rich vapors which, on encountering an impermeable barrier, may accumulate to form gas pockets with steadily increasing pressures. In the case of sufficiently high gas contents, the pressures may exceed lithostatic pressures leading to a blow-out or a “pneumatic” eruption (Dieng). Otherwise, gas may accumulate to form a stable pocket (Mt. Gambier). Minor leakage from such pockets may lead to surface discharges of CO2-rich gases as at Laacher See, re-absorption into shallow groundwater to the formation of the low-salinity, CO2-charged waters encountered at Lakes Nyos and Monoun. The occurrence of these high-CO2, low-temperature systems is likely to be favored in tectonically active regions, allowing deep, possibly mantle gases to rise, but with sufficiently low regional heat flows to prevent the establishment of large-scale geothermal activity.

Description: In February 1988, 60 near surface samples were taken on a track between 2°W in the English Channel, the Pentland Firth and the inner German Bight. Determinations were made on filtered and unfiltered samples. Concentrations of dissolved metals in the North Sea normalized to a salinity of 34.5 were Al 31, Cd 0.13, Co 0.13, Cu 3.4, Mn 6.2 and Ni 3.9 nM. In July 1984 the equivalent concentrations were Al 11, Cd 0.15, Co 0.15, Cu 4.3, Mn 12 and Ni 3.6 nM. Distinct regional differences were detectable which can be related to the origin of the water, differing river inputs, and solution-solid phase exchange reactions. The degree of the influence of exchange reactions was investigated through the concept of Kd, the distribution coefficient. A Kd of 105 ml g−1 for Al is consistent with other observations and explains the relatively high concentrations of dissolved Al detected in the English Channel on this cruise. The data suggest a higher Kd for Mn approaching 106 ml g−1. The high Mn Kd coupled to higher suspended sediment loads in winter may be sufficient to explain the lower concentration of dissolved Mn in winter. Comparison of concentrations across the shelf break suggests that for all the metals studied, the European Shelf is a source of dissolved metals to the deep sea. Calculations based on the limited available data indicate that this export is of similar magnitude to the fresh water input of dissolved metals.

Description: An overview is given of the multinational investigations carried out at 47°N 20°W for the period 24 April–31 May, with the main emphasis on the succession of plankton communities and the flux of organic carbon through various plankton components. The depth of the upper mixed layer decreased rapidly after 25 April, triggering the start of the spring bloom that developed within a 2-week period. Chlorophyll a stocks integrated to 80 m water depth reached peak concentrations during the first 10 days in May. The observed decline was partly due to the seasonal development, but also may have been influenced by changes in water masses associated with a cyclonic eddy. Primary production ranged from 50 to 150 mmol C m−2 day−1 with highest values in the first half of May. After the first bloom phase, dominated by diatoms, nanophytoplankton gained more importance as primary producers when silicate was depleted. Stocks of bacteria, microzooplankton and mesozooplankton increased in the second half of May. Bacterial production averaged 30% of primary production and probably metabolized a large amount of dissolved organic carbon (DOC) per day, but due to uncertain carbon conversion efficiencies total bacterial carbon consumption is difficult to estimate. Largely daily changes in the DOC standing stock could not be reconciled with the measured primmary production and are probably an expression of spatial rather than temporal variations. Microzooplankton was found to consume around 64% of primary production in the second half of May. Grazing estimates for mesozooplankton varied but seem to be small (〈5% of primary production) for most of the investigation period. The small mesozooplankton size classes (〈1 mm) dominated biomass and grazing. Vertical particulate organnic carbon (POC) flux measured by sediment traps in 150 m depth was around 9.8 mmol C m−2 day−1 representing approximately 11% of primary production. The spring bloom pulse of particle flux reached the deep ocean and benthos 4–6 weeks after the surface water peak.

Description: Altimetric data from Geosat and some critical hydrographic measurements were used to estimate in real time the mesoscale physical oceanographic environment surrounding the Joint Global Ocean Flux Study (JGOFS) 1989 North Atlantic Bloom Experiment. Three cyclonic eddies, including an exceptionally large one, evolved and interacted over the 10 weeks of observations. Subsequent analysis of all available hydrographic data confirmed the real time estimates and provided further quantitative information concerning the mesoscale and submesoscale structure of the upper ocean. Remotely sensed indicators of near-surface chlorophyll content reveal significant biological variability on these wavelengths. The altimetric and hydrographic data have been assimilated into a dynamical model to produce optimal estimates of physical fields of interest as they evolve in time for use in physical and biological process studies

Description: The influence of increasing amounts of surfactants on the toxicity of hydrocarbons was determined using the bioluminescence inhibition test (Microtox test). Three biogenic and three synthetic surfactants were tested against the water-soluble fractions (WSF) of crude and weathered Ekofisk oil, phenol, and naphthalene. Surfactant concentrations below 100 mg litre−1 lowered the toxicity of the WSF, indicating an antagonistic interaction reducing the toxicities of surfactants and hydrocarbons. At concentrations greater than 100 mg litre−1 the toxicity rose again and was higher than the untreated WSF. The point of reversal seemed to be the critical micelle concentration, at which the formation of oil/water emulsions is possible.

Description: Regional terrane analysis has been combined with a global evaluation of plate kinematics to produce a new tectonic model for the Mesozoic evolution of western North America and its associated marginal seas. The model employs a two-tiered data reliability ranking system to resolve conflicts within data sets. The lower tier of the ranking system involves the assignment of a numerical rank to paleomagnetic and/or paleobiogeographic data based on each data set's reliability. The upper tier of the ranking system places the paleomagnetic and paleobiogeographic data in perspective by assigning a relative order of importance to different types of data. The most reliable data are considered to be “departure” (rift) and “arrival” (collision) times that are tightly constrained by independent data sets. Evidence of subduction and/or strike-slip motion also ranks high in the master ranking system. Paleomagnetic and vertebrate paleobiogeographic data come next in the hierarchy, followed by invertebrate and floral paleobiogeographic data. Application of this approach to a case study, the “Baja British Columbia” controversy, has resulted in a coherent model for the entire region.

Description: Biological and fishery features of the waves of abundance of Illex argentinus in three fishery regions −52°S (shelf with 180–230 m depths in exclusive economic zone of Argentina—EEZA), 46° and 42°S (continental slope with 600–800 m depths off the EEZA) in April–June 1990 were studied. According to age analysis of 629 statoliths made aboard, age-length structure of each wave of abundance were determined. In April–June active spawning migrations of I. argentinus were observed from feeding grounds located in limits 50–52°S along the continental slope northwards through 46° and 42° fishery regions. Only winter-hatched squids (hatched from June to September of the previous year) took part in migrations which were observed as waves of abundance in all three regions. Each migratory wave of abundance consisted of 2–4 successive monthly generations. The start of spawning movement was corresponded with the age and maturity state of the squid. Squid of all monthly generations began migrating from the 52°S region at a mean age of approximately 250 days, passed through 46°S at mean age 280 days and through 42°S at mean age 295 days. Males migrated 2–3 weeks earlier than females of the same generation. Rates of somatic growth were very low during migrations from 52° to 46°S (RDGR - 0.13% mantle length (ML) in mature males and 0.2% ML in maturing females). During movement from 46° to 42°S and, obviously further, mature squids practically ceased somatic growth. Estimated rate of migrations was 23.2–28.9 km day−1 (including current velocity), or 26–30 cm s−1 (0.47 body length s−1). Spawning was considered to occur on the continental slope of Uruguay and Brazil north of 35°S in July–August. Methodical approaches of efficient determination of squid age, growth and stock structure by means of investigation of squid biological features and statolith microstructure in each distinguished wave of abundance were elaborated.

Description: The effects of feeding a prepared surimi diet (fish-based) and a prepared pelleted diet (shrimpbased) on the survival, growth and feeding rate of the cuttlefish Sepia officinalis L. were evaluated during a 45-day experiment. One hundred and twenty juveniles of laboratory cultured cuttlefish (74.5 ± 12.36 g) were divided into three treatments and were fed thawed shrimp (control), pellets or surimi. Survival rates on these diets were 95.0%, 67.5% and 22.5%, respectively. Preliminary data indicated that the low survival of cuttlefish fed surimi may have been caused by low levels of copper in their blood (131 vs 244 μg/ml) since copper is required for their respiratory blood pigment, hemocyanin. Instantaneous growth rates were 2.71 % body weight BW/day for cuttlefish fed raw shrimp, 0.33% BW/day for cuttlefish fed pellets, and 0.54% BW/day for cuttlefish fed surimi. The feeding rate of cuttlefish fed shrimp was high (6–8% BW/day). The feeding rate on pellets increased with time (from 〈 1 to 3% BW/day) but never reached the level for raw shrimp. The feeding rate on surimi increased to equal the rate for raw shrimp during days 1–30 (8 to 9% BW/day) and thereafter decreased (〈4% BW/day). In conclusion, there was a major distinction between the palatability of a prepared diet and the ability of that diet to support growth. Surimi was highly palatable but resulted in poor survival, suggesting low nutritional quality. In contrast, pellets were less palatable but produced maintenance growth. Development of practical surimi diets will require supplementation of the surimi with soluble micro- and macronutrients.

Description: Changes in marine ecosystems can be manifested in many different ways, on different temporal and spatial scales. Seabirds are top consumers in marine foodwebs and offer opportunities to detect and assess the biological effects of changes in physical parameters (sea-surface temperature [SST], salinity, depth of thermocline etc.) of the marine ecosystem. We compare six-eight years' of data on the biology (diet, and breeding success) of four species of seabird (arctic tern Sterna paradisaea and common tern S. hirundo, which feed at the sea surface; and Atlantic puffin Fratercula antica and razorbill Alca torda, which dive 30-60 m for their prey) breeding on Machias Seal Island (MSI) in the Bay of Fundy with both our own meteorological and oceanographic measurements, and with standard measurements from conventional sources. These are compared with fisheries data on changes in the main prey of all the seabirds concerned (juvenile or '0-group' herring Clupea harengus) which are the most direct link between the seabirds and the physical properties of the marine system. We explore relationships between seabird productivity and diet, and other aspects of both herring biology (larval surveys, and fat content) and oceanography (SST data from the island, and remotely sensed data from the entrance to the Bay of Fundy). Timing of laying by puffins followed SST variation at neither the local (MSI) nor regional scales, but at the scale of the North Atlantic, following the trend of populations breeding off northern Norway. The proportion of herring in the diet of terns over 6 years varied inversely with herring larval abundance the previous fall; this relationship was not statistically significant in the puffin and razorbill. A major new finding is the considerable (approximately 50%) inter-annual variation in the energy density (fat content) of juvenile herring that are the main seabird prey; breeding success of both species of tern varied in parallel with the energy density of juvenile herring in the diet until the last two years of the study, when sandlance (Ammodytes sp.) and euphausid shrimp predominated in the diet. Our long-term research approach combines traditional population monitoring (of numbers of breeding birds) with demographic, behavioural and environmental monitoring, to provide new understanding of the marine ecosystem as well as of seabirds.

Description: Sediments obtained from the NE Thetis Deep during the Sonne cruise SO-29 consist of a manganite-facies and various types of Fe-facies (hematite, magnetite, goethite, and lepidocrocite facies). The sediments have a chemical and mineralogical composition similar to some of the lithological units previously described from the Atlantis II Deep, 160 km to the southeast. In contrast to the Atlantis II Deep, no stable brine pool recently exists in the NE Thetis Deep. However, based on the Fe/Mn fractionation in the Fe-facies types an intermittent brine filling of the NE Thetis Deep has probably existed. We propose that the formation of the brine pools correlate to the volume of discharging fluids. The chronology of hydrothermal deposition in the NE Thetis Deep seems to correlate with similar events in the Atlantis II Deep, suggesting that major tectonic events in the Red Sea may have caused large-scale pulses of hydrothermal activity.

Description: Productivity regime and phytoplankton size structure are described for two different epipelagic systems in the tropical/subtropical Northeast Atlantic Ocean investigated during 9–11 day drift studies in spring 1989 in the JGOFS North Atlantic Bloom Experiment, 18°N, 30°W and 33°N, 20°W. At the 18°N study site, an oligotrophic system was encountered. The water column above the main pycnocline at about 50–60 m depth was nutrient-depleted, and both chlorophyll and primary production displayed subsurface maxima at the nutricline. Picoplankton was the dominant size fraction, accounting for 78–90% of chlorophyll and 83–98% of primary production. Synechococcus-type coccoid cyanobacteria were the dominant picoplankters. The hydrographic situation was characterized by high small-scale variability; the most interesting feature was the intrusion of nutrient-depleted Subtropical Salinity Maximum Water into the euphotic zone, whose impacts on the productivity regime are discussed. At 33°N study site, a post-bloom situation was encountered. Although the euphotic zone was nutrient-depleted, higher amounts of larger phytoplankton were present, the contribution of picoplankton being 42–53% of chlorophyll and 42–86% of primary production. Over the course of the drift study, subsurface maxima of chlorophyll and productivity evolved, the contribution of picoplankton having increased. Picocyanobacteria again were the dominant picoplankters. At both study sites the profiles of abundance ratios of picocyanobacteria to picoeucaryotes cell numbers proved to be a useful tool to characterize water masses.

Description: The origin and the spreading of the shallow Mediterranean water core (Ms) in the Iberian basin is discussed with a quasi-synoptic hydrographic data set enhanced by chlorofluoromethane (CFM) measurements. Its characteristic density level is found to be σt = 27.4. Characterized by high temperature and CFM values, Ms enters the Iberian basin in the region of Cape St Vincent between depths of 500–750 dbar. A heat anomaly of 〉11.8 × 109 J m−2 is chosen as the boundary between the presence of Ms and the background field. The core is found in a tongue-like shape as well as in separate isolated eddies of both cyclonic and anticyclonic circulation. Using the optimum multiparameter analysis (Tomczak and Large, 1989, Journal of Geophysical Research, 94, 16141–16149), the North Atlantic Central Water (NACW), which mixes with the Mediterranean outflow to form Ms, turned out to be in the mean 1°C warmer and 0.11 saltier than in regions with minor Mediterranean influence. This points to the Gulf of Cadiz as the origin of Ms, where the Mediterranean oufflows is in contact with NACW of the appropriate characteristics.

Description: Gas chromatography-mass spectrometry (GC-MS) analyses of organic concentrates from eastern Mediterranean surface water show that dissolved fossil fuel residues are dominated by unsubstituted aromatic hydrocarbons and heterocyclic aromatics and thus resemble products of incomplete combustion. Deviating from this interpretation, preferential photochemical oxidation of alkyl-substituted aromatics is suggested as the principal causative mechanism, although, especially near land-based sources. the influence of combustion-derived unsubstituted aromatics is not defined. Total concentrations of dissolved aromatics as determined by GC-FID (flame ionization detection) and GC-MS from a limited data subset were in reasonable agreement with UV fluorescence measurements of dissolved/dispersed oil residues. The same preponderance of unsubstituted aromatics over their alkyl derivatives was found in extracts of the particulate phase, but concentrations were small relative to alkanes and/or alkenes of recent marine biosynthetic origin. CPI (carbon preference index) values of higher molecular weight n-alkanes indicated varying contributions of plant waxes to the particulate hydrocarbon pool. CPI values of corresponding dissolved n-alkanes were found to be near unity, indicating fossil fuel origin. Despite differences in higher molecular weight n-alkane CPI values and the predominance of recent biosynthetic aliphatics, the similarity of dissolved and particulate aromatic fractions suggests limited adsorption by particles of fossil fuel derived hydrocarbons and heterocyclics.

Description: Saudi Arabian coastal waters near sandy beaches, severely contaminated with crude oil released in Kuwait during the 1991 Gulf War, as well as underlying sediments and a few bivalves, were analysed to assess concentrations and composition of petrogenic hydrocarbon mixtures and structurally related oxidation products. Concentrations of dissolved oil residues determined by UV spectrofluorometry (UVF) near oil deposits on beaches did not exceed 3.5 μg l−1; concentrations dropped to approximately 1/10th of this value a few miles offshore. Gravimetric concentrations of unfractionated lipophilic material extracted from large volumes of seawater at the same stations were up to 10 times those determined by UVF. After chromatography on silica gel, individual petroleum hydrocarbons in the low polarity fractions and oxidation products in the polar fractions were characterized by their spectra (GC/MS) and quantitated by Selected Ion Monitoring (SIM) GC/MS. Concentrations of oxidation products (ketones, aldehydes, alcohols) of aromatic hydrocarbons exceeded those of their parent compounds by more than an order of magnitude. Significant concentrations were also found of the presumably pyrogenic triplett sensitizer anthraquinone. Contributions to polar fractions of water extracts by biosynthesized lipids were negligible. UVF determinations appear to underestimate concentrations of dissolved oil residues, because many oxidation products have lower fluorescence quantum yields than the respective parent hydrocarbons. Their ecotoxicological properties are unknown. Concentrations measured in sediments by UVF ranged from 13 to 540 μg g−1 dry wt and 0.5 to 103 μg g−1 as measured by gas chromatography with flame ionization detection (FID GC). Bivalves ranged from 0.8 to 1.5 μg mg−1 extractable organic matter (EOM) by UVF, and 0.1 to 0.3 μg mg−1 EOM by GC analysis. PAHs were identified in sediment and bivalve extracts by GC/MS and quantitated by SIM GC/MS. None of the relatively water soluble alkylbenzene photo-oxidation products found in water samples nor any higher molecular weight quinones could be detected in sediment extracts. However, ion chromatograms strongly suggest the presence of numerous high molecular weight aromatics in that matrix.

Description: As part of the NOAA/ROPME/MSRC sponsored assessment of the coast of Saudi Arabia, heavily impacted by the large oil spills of the 1991 Gulf War, we measured benthic community respiration (R) and primary production (P) rates in shallow subtidal basins near heavily oiled coastlines. Study sites were located in zones predicted to be basins of maximum deposition of any oiled sediments likely to wash off the adjacent coast and in reference bays predicted to be clean and unaffected. We measured oxygen exchange using in situ benthic respirometers and analysed petroleum hydrocarbon (PHC) levels in the near surface sediments at five stations. We concentrated our efforts in mud habitats to complement related studies in seagrass habitats. Measured community R rates ranged from a low of 700 μM m2 h−1 in coarse sand sediments with total organic carbon content (TOC) of only 0.16% of dry wt to the highest rate of 2184 μm m−2 h−1 in finer mud-sand habitats with 0.39% TOC. All measured rates were in the range of literature values for shallow marine sediments at temperatures of 17 to 19°C. Sediment oil content was 13–540 μg g−1 dry wt by ultraviolet fluorescence (UVF) analysis and 0.5–103 μg g−1 by gas chromatography (GC). Benthic P rates, calculated as light minus dark changes in dissolved oxygen, ranged from a low of 1162 μm m−2 h−1 at the most heavily oiled site to a high of 5216 μm m−2 h−1 at less oiled sites. While a weak inverse relationship between benthic P and sediment oil content was not significant statistically due to the small number of samples, a significant inverse relationship was found between the ratio of production to respiration (P/R) and the total petroleum content of the sediments by UVF. The effect appears to be driven more by differences in production than an effect on respiration which showed little relationship with either oil content or productivity. We conclude that within 1 year after the oil grounded on the intertidal sands of Saudi Arabia, the levels of oil in subtidal benthic sediments had decreased in most habitats to levels that did not show community stress by our oxygen measurements. Rather, long term damage to benthic subtidal habitats was limited only to enclosed bays adjacent to the most heavily oiled coastlines. Preliminary estimates of yearly P converted to carbon units indicates that the shallow mud sediments of the Gulf are at least as productive as most oligotrophic water columns. Since benthic habitats covered by seagrass, algae beds or coral reefs are likely to have even higher production rates, we conclude that benthic processes contribute significantly to the overall carbon flux in the Gulf ecosystem.

Description: A method for the collection of large-volume samples of oceanic particles is described. Near-surface seawater is pumped from below the ship to a continuous-flow centrifuge at rates of up to 1.2 m3 h−1. The seawater is in contact with polyethylene, polypropylene, Teflon and titanium materials only. The retention efficiency of the centrifuge for marine particles is the same as for standard membrane filters, as shown by comparisons with separate samples from Go-Flo bottles. The pumping system is non-contaminating with respect to both particulate and dissolved species. Several subsampling facilities for additional chemical constituents and other parameters can be supplied simultaneously due to the modular design of the system and the high flow rates

Description: Sediments of 13 piston cores from opposite continental slopes of the South China Sea, off southern China and Sabah (northern Borneo), were analyzed by sedimentological methods and dated by oxygen isotope stratigraphy. Sediments mostly consist of hemipelagic clay with 20% carbonate off Sabah and 40% off China. We calculated terrigenous and carbonate accumulation rates for up to 11 time-slices from the Holocene to oxygen-isotope stage 6. Terrigenous accumulation rates generally increase with water depth and reach a maximum at the middle slope off Sabah and at the lower continental slope off China. During glacial and interglacial times this distribution pattern did not markedly change, despite an increase of accumulation rates for glacial periods by a factor of 2 to 5 compared to interglacial periods. Rates are negatively correlated with positions of sea level, which controls the partition of fluviatile terrigenous material for deposition on shelf, slope, and abyssal plain. Carbonate accumulation rates are higher off China by a factor of 2 compared to Sabah, probably indicating higher calcareous plankton productivity.

Description: The Vema Channel represents a prominent location for the nortward flow of bottom water in the subtropical western South Atlantic. A recent multibeam echo-sounding survey of the Vema Sill on board F.S. Meteor revealed a narrow and shallow portion of the Vema Channel at 31°12′S, 39°24′W, the Vema Sill. The survey also showed the remarkably asymmetric shape of the sill region, suggesting an interaction between the bottom flow and the shape of the channel.

Description: Live observations, cytological characteristics and biometrical measurements on Miliolinella subrotunda (Montagu, 1803) sampled from the northern and southern Atlantic Ocean are presented.M. subrotunda facultatively constructs a long, detritic tube lifting the test several millimeters above the sediment surface. A thickened conical base anchors the construction on the sediment surface and a long, flexible tube protrudes into the velocity profile of the bottom currents. The miliolid test is placed on top, surrounded by the uppermost part of the tube. This construction allows the organisms to feed in the particle stream above the sediment surface. In comparison to species living in and on the surface sediments,M. subrotunda apparently shows higher nutritional values in food ingested and larger amounts of reserve substances. Characteristics of the shape and structure that reduce drag on the tubes include a broadened conical base, a flexible tube, and a rounded top. From biometrical measurements it is concluded, that the tubes are constructed over a short period of their ontogeny.

Description: The Houtman Abrolhos Islands, situated at the western passive margin of the Australian continent, consist of a series of shelf-edge coral reefs. The central platforms of the reefs are Late Pleistocene in age and are generally some 3–5 m above present sea level. The uppermost part of the Last Interglacial reefs normally has an upward-shallowing sequence, consisting of coral framestone, coralline algal bindstone and skeletal grainstone to rudstone. This sequence represents deposition in water depths of less than 2 m, and provides a good indicator of sea level. High-precision mass-spectrometric dates of corals from the Abrolhos reefs, including dates obtained from drill cores, arological, isotopic and stratigraphic criteria are established for the selection of suitable samples for dating and for assessing the reliability of dates. Using the screened dates and the stratigraphic evidence, the timing and character of the sea level variations of the Last Interglacial in the Abrolhos region are examined. The data show that sea level of the Last Interglacial in the Abrolhos was 4 m below its present height by ca. 134 ka BP and probably reached about 2 m above present height at ca. 133 ka BP. The exact time at which sea level reached its peak (6 m above present sea level) cannot be determined from our data. But it is clear that the sea level high stand of the Last Interglacial lasted until ca. 116 ka BP and that for much of the Last Interglacial sea level at the Abrolhos was at a height of about 4 m above its present level

Description: Accurately weighed aliquots of the ∼ 500-Ma-old interlaboratory standard hornblende MMHb-1 were mixed with known quantities of a ∼ 100 Ma-old Himalayan biotite and subjected to normal Full-size image (〈1 K) incremental heating analysis. The addition of the biotite created monotonically increasing apparent ages, similar to profiles interpreted as showing Ar diffusive loss in the literature. The release of Ar from biotite dominates the low-temperature portion of the spectra and lowers the observed age. Lower Ca/K ratios in the first increments are consistent with contamination, but do not distinguish the composition of the contaminant phase. A large number of published amphibole “diffusive loss” profiles may, in fact, be due to contamination by biotite or other phases which release Ar at low extraction temperatures.

Description: Iceland straddles the mid-Atlantic spreading axis, between the Kolbeinsey Ridge to the north and the Reykjanes Ridge to the south. Published geochemical data from the Reykjanes Ridge show evidence for mixing between a MORB component and the Iceland plume. Available data from the Kolbeinsey Ridge suggest that similar mixing may not be occurring there. To investigate in detail the relationship between the Iceland plume and MORB along the Kolbeinsey Ridge, we have collected and analysed samples between the Tjo¨rnes and Spar fracture zones (ca. 67°–69°N). The 16 Kolbeinsey Ridge samples show limited isotopic variation and are characterised by relatively unradiogenic Pb (206Pb/204Pb= 17.912 to 18.053, 207Pb/204Pb= 15.404 to 15.453 and 208Pb/204Pb= 37.543 to 37.690, 87Sr/86Sr= 0.70280 to 0.70298, 143Nd/144Nd= 0.51307 to 0.51323). On the basis of their Rb, Sr, Nd, Sm, U, Th and Pb concentrations, the basalts are N-type MORB. Sr and Nd isotope ratios show significant systematic variations with latitude, becoming more enriched (87Sr/86Sr increases, 143Nd/144Nd decreases) towards Iceland, apparently supporting the classical model of plume-asthenosphere mixing. However, the Pb isotopes show no such relationship, and are thus inconsistent with this mixing model. On the basis of Pb and Sr isotope data it is possible to exclude the Iceland source as an end-member in the genesis of the Kolbeinsey Ridge basalts, implying that Iceland plume material does not flow northward along the Kolbeinsey Ridge. The isotopic variations within the Kolbeinsey data set can be attributed to heterogeneities in the MORB source. The boundary between the plume and MORB sources appears to coincide with the Tjo¨rnes Fracture Zone. This fracture zone may, by analogy with the Australia-Antarctic Discordance, overlie a zone of mantle convergence. The topographic anomalies over the Kolbeinsey and Reykjanes Ridges imply that hot, less dense material underlies them both. The absence of an Icelandic plume signature in the Kolbeinsey geochemistry, however, leads us to propose an asymmetrical shape for the plume, generated by a southerly component of flow in the Kolbeinsey MORB source. A similar flow direction has previously been proposed for the whole North Atlantic on the basis of independent mantle mass-balance calculations

Description: Moored Acoustic Doppler Current Profilers (ADCPs) were used to analyse the daily vertical zooplankton migration and its seasonality. One-year records of vertical velocity and acoustic backscatter were obtained at four stations in the Greenland Sea. Both parameters exhibited a diurnal cycle typical for vertically migrating zooplankton. Upward and downward migration occured in short periods approximately 5 h long, and peak migration velocities were around 1.5 cm s−1. Similar structures were observed at all four mooring sites in the 200–300 m depth range. Farther down, between 1000 and 1400 m, no daily migration was observed. Strong seasonal variations are evident, and both the phase and intensity of the migration pattern change with daylight as the season progresses. In summer and during the polar night the migration became very weak and was only detectable in the displacement of scattering layers. When the day/ night contrast was large, intense upward or downward motion was accompanied by sloping backscatter isopleths. We observed two main scattering layers, a deep layer that varies in depth with season and an almost invariable shallow scattering layer at about 150 m depth. The deep layer was interpreted as the “resting depth” of the migrating plankter, and the latter as their “feeding horizon”. Changes in the “resting depth” from about 400 m in autumn and spring to about 200 m in winter lead to seasonal variations in the migration distance. This behaviour is discussed with respect to environmental conditions.

Description: A comparative study of the mineralogy and geochemistry of sulfide deposits on mid-ocean ridges in the Northeast Pacific and the Mid-Atlantic reveals common characteristics associated with primary gold enrichment. Average gold contents of 0.8 to 5 ppm Au occur in sulfides from Southern Explorer Ridge and Axial Seamount (Northeast Pacific) and from the TAG hydrothermal field and Snakepit vent field (Mid-Atlantic Ridge). The enrichment of gold in these deposits is consistently related to a phase of late-stage, low-temperature (〈 300°C) venting. Concentrations 〉 1 ppm Au occur exclusively in pyritic assemblages and commonly with abundant Fe-poor sphalerite and a suite of complex Pb—Sb—As sulfosalts. Amorphous silica and, locally, barite or carbonate are important constituents of the gold-rich precipitates but do not contain gold themselves. High-temperature (350°C) black smoker assemblages, consisting dominantly of pyrite, chalcopyrite, pyrrhotite, isocubanite and abundant anhydrite are uniformly gold-poor (≤0.2 ppm Au). To the extent that individual sulfides can be mechanically separated, chemical analyses by neutron activation indicate that gold is most abundant in sphalerite (up to 5.7 ppm Au) but also occurs in pyrite and marcasite. Samples of sphalerite with abundant inclusions of fine-grained sulfosalts locally contain up to 18 ppm Au, suggesting that sulfosalts may be repositories for gold. No free gold has been observed at 4000 × magnification of polished specimens, indicating that the gold is present only as submicroscopic inclusions or as a chemical constituent within the sulfides. Samples from gold-rich deposits in the Northeast Pacific and Mid-Atlantic are compared with similar but relatively gold-poor sulfides from the Galapagos Rift and 13°N on the East Pacific Rise (EPR), and with barren sulfides from 11°N EPR, 21°N EPR, the Endeavour Ridge, and the Southern Juan de Fuca Ridge. Trace element analyses of more than 170 samples show that gold enrichment in almost all of the deposits is associated with high concentrations of Ag, As, Sb, Pb and Zn, and locally with high Cd, Hg, Tl, and Ga. In contrast, gold is typically depleted in samples with high Co, Se, and Mo. The close association of Au with Ag, As, Sb, and Pb may reflect the common behavior of these metals as aqueous sulfur complexes (e.g., [Au(HS)−2]) at low temperatures. Similar mineralogical and geochemical associations are observed in sulfide deposits from modern back-arc settings and in the ancient geologic record.

Description: 50 m of Middle Eocene pure radiolarian ooze were drilled at ODP Site 660 in the equatorial East Atlantic, 80 km northeast of the Kane Gap. The oozes comprise a 10 m high and 2 km broad mound of seismic reverberations, covered by manganese-rich sediment, and contain trace amounts of sponge spicules and diatoms, negligible organic carbon (0.15%), clay, and variable amounts of pyrite. The yellow to pale brown silty sediments are relatively coarse-grained (30–45% coarser than 6 μm), little bioturbated, and commonly massive or laminated on a cm-scale. The unlithified radiolarian ooze may indicate an interval of high oceanic productivity, probably linked to a palaeoposition of Site 660 close to the equatorial upwelling belt during Middle Eocene time. The absence of organic matter, however, and both the laminated bedding and the mound-like structure of the deposit on the lower slope of a continental rise indicate deposition by relatively intense contour currents of oxygen-rich deep water, which passed through the Kane Gap, winnowed the fine clay fraction, and prevented the preservation of organic carbon. The ooze may be either a contourite-lag deposit, or a contourite accumulation of displaced radiolarians, originating south of the Kane Gap and being deposited in its northern lee, thus documenting the passage of a strong cross-equatorial bottom-water current formed near Antarctica. These Eocene contourites may be an analogue for ancient radiolarites in the Tethyan Ocean.

Description: In situ observations of microhabitat preferences of living benthic foraminifera are presented from sediments of the Norwegian-Greenland Sea, the upwelling area off northwestern Africa and the shallow-water Kiel Bight (Baltic Sea). Certain foraminiferal species (e.g.Cibicidoides wuellerstorfi andRupertina stabilis) can be regarded as strictly epibenthic species, colonizing elevated habitats that are strongly affected by bottom water hydrodynamics. Large epibenthic foraminifera (e.g.Rhabdammina abyssorum andHyperammina crassatina) colonize the sediment surface in areas where strong bottom currents occur and might have by virtue of their own size an impact on the small-scale circulation patterns of the bottom water. Motile species changing from epifaunal to infaunal habitats (e.g.Pyrgo rotalaria, Melonis barleeanum, Elphidium excavatum clavatum, Elphidium incertum, Ammotium cassis andSphaeroidina bulloides) are regarded here as highly adaptable to changes in food availability and/or changing environmental conditions. This flexible behaviour is regarded as a dynamic adaptation to optimize food acquisition, rather than a static concept leading to habitat classification of these ubiquitous rhizopods.

Description: The Houtman Abrolhos reefs, situated on the western continental margin of Australia, occupy a transitional position between cool-water shelf carbonate sediments to the south and more tropical environments to the north. Their existence at the outer limits of the geographical range for coral reef growth is a result of the warm, poleward-flowing Leeuwin Current. Though the modern reefs differ ecologically from tropical reefs, their geological characteristics have been little known until recently. Each of the three island groups in the Abrolhos consists of a central platform of Last Interglacial reefs, about which windward and leeward Holocene reefs have developed asymmetrically. In the Easter Group the subtidal windward reef in the west is ca. 10 m thick and is backed by a leeward-prograding, lagoon sand sheet which is 0–3 m thick. The emergent parts of the leeward reefs in the east consist of an upward-shallowing sequence comprising reef facies, peritidal rudstone facies, and coral rubble storm ridges. This is underlain by over 26 m of Holocene reef facies. Coring and dating of the Holocene reefs (using both TIMS and 14C methods) in the Easter Group has shown significantly different lithofacies in the windward and leeward reefs, and has allowed reconstruction of Holocene reef growth and sea-level history. Coralline algal bindstones and interbedded coral framestone facies characterise the relatively slow-growing windward Holocene reefs, whereas the fast-growing leeward reefs consist of coral framestone facies which are dominated by Acropora. The leeward reefs commenced growth about 10,000 years ago and the Morley reef grew to 0.3 m above present sea level by 6400 years B.P., recording a relative high sea-level event. This generated Holocene constructional topography characterised by “blue-hole” terrain. Windward Holocene reef growth commenced after 8200 years B.P. following erosion of the windward part of the Last Interglacial platform. High wave energy and competition with macroalgae limited coral growth, and the coralline algal-dominated windward reefs grew more slowly to sea level. The Holocene sea-level record provided by dates from the 26 m core of the Morley reef (a “keep-up” reef) is the first such record from the western continental margin of Australia.

Description: The dewatering of fine grained sediment piles in accretionary wedges is controlled by zones of active deformation. Episodic hydrofracture in these zones enhances permeability, enabling fluid flow to be faster than the speed of underthrusting. Here I investigate the mechanics of simultaneous shear failure and hydrofracture in muddy rocks as a function of the faulting mode. The physical properties of model rock types are chosen to represent uncemented mud or cherty/marly mudstones that have undergone significant diagenesis. During thrust faulting, hydrofracture always requires pore fluid pressures in excess of the lithostatic load, whereas shallow level wrenching or normal faulting permits hydrofracture at hydrostatic pressures significantly lower than lithostatic load. All three faulting modes are expected to occur in an accretionary wedge attempting to dynamically maintain its critical taper. The model computations indicate that in the upper 80-120 m of a section of "soft'' mudstone hydrofracture inevitably accompanies wrench or normal faulting. "Hard'' mudstones inevitably hydrofracture to depths of up to 1400 m during normal faulting. These differences in mechanical behaviour have profound consequences for fluid venting capabilities of accretionary wedges. They influence hydrocarbon trapping, and play a role in the localisation of mud diapirs and mud volcanism.

Description: During a R.V. Meteor JGOFS-NABE cruise to a tropical site in the northeast Atlantic in spring 1989, three different vertical regimes with respect to nitrate distribution and availability within the euphotic zone were observed. Besides dramatic variations in the depth of the nitracline, a previously undescribed nose-like nitrate maximum within the euphotic zone was the most prominent feature during this study. Both the vertical structure of phytoplankton biomass and the degree of absolute and relative new production were related to the depth of the nitracline, which in turn was dependent on the occurrence/non-occurrence of the subsurface subtropical salinity maximum (S(max)). The mesoscale variability of the nitracline depth, as indicated from a pre-survey grid, and published data on the frequent occurrence of the S(max) in tropical waters suggest higher variability of new production and F-ratio than usually expected for oligotrophic oceans. The importance of salt fingering and double diffusion for nitrate transport into the euphotic zone is discussed.

Description: Al- and Ti-rich smectites associated with alkaline volcanic rocks were dredged during several cruises of the German research vessel “SONNE” as part of an extensive survey of manganese crusts in the Central Pacific seamount region. X-ray diffraction, chemical composition and infrared spectroscopy suggest that the smectites are constituents of the nontronite-beidellite solid solution series. X-ray fluorescence analyses yield considerable amounts of Al2O3 and Fe2O3 averaging 14.5 and 12.4 wt%, respectively. According to ASTM data the smectites are Al-rich nontronites rather than Fe-rich beidellites. A TiO2 content of up to 4.9 wt% is thought to be due to anatase impurities. δ18O-values in the range of +23.8 to +21.0‰ vs. SMOV indicate formation temperatures of 32–48°C. The rare-earth element patterns of the nontronitic smectites and associated alkaline volcanics are almost identical, showing a relative enrichment of light and a depletion of heavy rare-earth elements. It is concluded that the smectites formed as low-temperature alteration products during interaction of seawater with cooling basaltic/alkaline rocks rather than by mixing of hydrothermal fluids with seawater.

Description: A closely spaced grid of seismic reflection profiles has permitted a description of the structure of the Vesterisbanken Seamount (Greenland Sea) and the distribution of the surrounding sediments. This isolated seamount is situated at 73°30′N, 9°10′W in the Greenland Basin and rises from the basin floor at a water depth of about 3100 m to ∼ 130 m below sea level; the maximum inclination of its slope is 26°. It is of basaltic origin, and reveals chaotic reflectors on the seismic profiles. No inhomogeneities are visible within the volcanic rocks of Vesterisbanken and the basement complex surrounding it. Dredge samples from the summit of Vesterisbanken reveal an age of ∼ 100,000 years. In the seismic records, there was no sediment cover discernable on top of or on the flanks of the seamount. At the base of Vesterisbanken, the seismic reflection characteristics suggest an alternation of sediments and basaltic rocks, the latter probably being the result of young lava flows. In some places the volcanic rocks disturb the sedimentary sequence to such a high degree, that the stratification is virtually eliminated. Volcanic activity also occurs in the vicinity of the seamount: for example, about 20 km northwest of Vesterisbanken an intrusion has pierced through 1000 m of sediment, almost reaching the seafloor. The sediment thickness is variable and it smooths the irregular basement topography. In addition, the sediment is characterized by local unconformities associated with onlap structures.

Description: Carbonate deposition at two core sites in the subarctic Pacific (48°N, 133°W; 2.9 km and 3.7 km water depth) follows the standard Pacific carbonate cycles, with glacial values being increased over interglacial values. Benthicδ13C follows the global trend; that is, glacial values are more negative than interglacial values. Comparison with the benthicδ13C record of North Atlantic DSDP Site 552 (56°N, 23°W; 2.3 km water depth) shows the North Pacific records to be nearly in phase with and continuously more negative relative to the North Atlantic record. This suggests that concentrations of∑CO2(org) were permanently higher in the North Pacific than in the North Atlantic during the past 750,000 years conceivably supporting the hypothesis that there was no deep-water forming in the late Pleistocene North Pacific. Whereas one would expect that the North Pacific deep waters were continuously more corrosive to carbonates than deep waters in the North Atlantic, carbonate deposition at the deep North Pacific core sites is enhanced during glacial periods, and occasionally higher than at shallow North Atlantic Site 552 even though Site 552 was probably above lysocline-depth during most of the late Pleistocene. This apparent paradox can be resolved only by invoking an increase in alkalinity in the glacial North Pacific which would have increased the degree of carbonate ion saturation and thereby improved the state of carbonate preservation.

Description: Dissolved silica (Si) and inorganic germanium (Ge) concentrations were measured in hydrothermal fluids from black smoker vents on the East Pacific Rise (21°N EPR) and the Southern Juan de Fuca Ridge (45°N SJdFR: North and South Cleft Sites, Axial Volcano). These typically display end-member concentrations ranging from 16 to 23 mM (Si) and 150 to 280 nM (Ge), and end-member Ge/Si ratios clustering between 8 and 14 × 10−6, more than 10-fold greater than the ratio entering the ocean via rivers (0.54 × 10−6) and being recycled in seawater (0.7 × 10−6). ‘Excess’ concentrations of dissolved Si and Ge above oceanic background are observed in mid-water hydrothermal plumes over mid-ocean ridge (MOR) spreading centers on the Southern EPR (SEPR) (10°–20°S) and the SJdFR. The largest Si and Ge concentration anomalies occur over the North Cleft Segment of the SJdFR. These are a factor of three greater than anomalies over the SEPR (10°–20°S). Excess Ge correlates with excess3He in plumes at a Ge/3He molar ratio of about 1 × 104, approximately the same ratio as in black smokers. These observations, combined with low abundances of Ge in Fesingle bondMn-rich metalliferous sediments, suggest that Ge (and Si) behave conservatively in mid-ocean ridge hydrothermal plumes. A simple ocean Si and Ge balance, constrained by the global river silica flux and Ge/Si ratios in hydrothermal vents, rivers and biogenic silica, suggests that the global hydrothermal silica flux is about 1–4 × 1011 mole yr−1, much lower than that estimated from3He. Either (1) 70–80% of the Ge flux to the ocean is removed in as-yet undiscovered sinks (not opal), or (2) only 10% of the mantle to ocean3He and heat fluxes is associated with MOR hydrothermal convection through the 350°C isotherm (90% is off-ridge), or (3) the oceanic Ge/Si,3He/ (and87Sr86Sr) balances today are far from steady-state.

Description: Polysyncraton lacazei (Giard), a colonial tunicate of the western Mediterranean, seems to be well-protected against epibiosis. Out of several thousand potential colonizers estimated, only one kamptozoan species, Loxocalyx sp., is found with some regularity (less-than-or-equal-to 21%) on the colonial surface. The results in this paper suggest the existence of overlapping mechanical, chemical and extrinsic adaptations with a good antifouling potential.

Description: We report the Sr, Nd and Pb isotopic compositions (1) of 66 lava flows and dikes spanning the circa 15 Myr subaerial volcanic history of Gran Canaria and (2) of five Miocene through Cretaceous sediment samples from DSDP site 397, located 100 km south of Gran Canaria. The isotope ratios of the Gran Canaria samples vary for 87Sr/86Sr: 0.70302–0.70346, for 143Nd/144Nd: 0.51275–0.51298, and for 206Pb/204Pb: 18.76–20.01. The Miocene and the Pliocene-Recent volcanics form distinct trends on isotope correlation diagrams. The most SiO2-undersaturated volcanics from each group have the least radiogenic Sr and most radiogenic Pb, whereas evolved volcanics from each group have the most radiogenic Sr and least radiogenic Pb. In the Pliocene-Recent group, the most undersaturated basalts also have the most radiogenic Nd, and the evolved volcanics have the least radiogenic Nd. The most SiO2-saturated basalts have intermediate compositions within each age group. Although the two age groups have overlapping Sr and Nd isotope ratios, the Pliocene-Recent volcanics have less radiogenic Pb than the Miocene volcanics. At least four components are required to explain the isotope systematics of Gran Canaria by mixing. There is no evidence for crustal contamination in any of the volcanics. The most undersaturated Miocene volcanics fall within the field for the two youngest and westernmost Canary Islands in all isotope correlation diagrams and thus appear to have the most plume-like (high 238U/204Pb) HIMU-like composition. During the Pliocene-Recent epochs, the plume was located to the west of Gran Canaria. The isotopic composition of the most undersaturated Pliocene-Recent volcanics may reflect entrainment of asthenospheric material (with a depleted mantle (DM)-like composition), as plume material was transported through the upper asthenosphere to the base of the lithosphere beneath Gran Canaria. The shift in isotopic composition with increasing SiO2-saturation in the basalts and degree of differentiation for all volcanics is interpreted to reflect assimilation of enriched mantle (EM1 and EM2) (cf. [1]) in the lithosphere beneath Gran Canaria. This enriched mantle may have been derived from the continental lithospheric mantle beneath the West African Craton by thermal erosion or delamination during rifting of Pangaea. This study suggests that the enriched mantle components (EM1 and EM2) may be stored in the shallow mantle, whereas the HIMU component may have a deeper origin.

Description: A mechanistic account of skeletal density band formation in massive colonies of Porites is developed by linking observations from vital staining of growing skeletons with measurements of density band characteristics, dissepiment spacing and the depth to which skeleton was occupied by tissue. Three growth processes contribute to density band formation. First, addition of new skeleton at the outer surface of the colony. Second, thickening of existing skeleton through the depth of the tissue layer (tissue usually occupies skeleton formed over the last 4–13 months). Third, the density pattern is then modified by periodic and abrupt uplift of the lower margin of the tissue layer which occurs about every 30 days. Uplift is associated with formation of new dissepiments and produces a fine density band at the lower margin of the tissue layer. Less regular, fine bands are formed within the tissue layer probably as a result of variations in calcification at the colonial surface. X-radiography of skeletal slices compresses and combines the results of these mechanisms making it difficult to distinguish the contribution of individual mechanisms to the overall X-ray image. The relative importance of the three mechanisms — extension, thickening and tissue uplift — to overall skeletal growth may differ between individual colonies. Variability in the way the mechanisms operate and combine may account for widely differing reports of coral density banding.

Description: During cruise ARK IV/3 with RV Polarstern (1987) volcanic rocks were recovered from the Nansen-Gakkel Ridge (NGR), a slow spreading (half rate approximately 0.5 cm) ridge with an axial depth of more than 5000 m. The NGR is one of the slowest and deepest mid-ocean ridges so far known and calculations based on the distance of sampling location from the axial valley yielded ages of approximately 600 ka for the rocks investigated here. According to petrographic and geochemical results i.e. spinifex textures, mg 〉 70 and MgO 〉 9 wt.%, the volcanics are termed komatiitic basalts. Dark spherical droplets of basanitic composition within the komatiitic basalts are believed to be relicts of an incomplete magma-mixing whose basanitic end-member could well account for the enriched character of the NGR basalts in terms of rare earth elements, Ti and incompatible trace elements. Based on Nd-isotope as well as high Sm/Nd ratios, mantle metasomatism (i.e. veined-mantle model) could be responsible for the enrichment of incompatible trace elements in the source region of komatiitic basalts of the NGR.

Description: Crustal xenoliths in three Cenozoic volcanic fields of West Germany, the Northern Hessian Depression (NHD), the Eifel and the Urach/Hegau, include medium to high-grade meta sedimentary and felsic to mafic meta-igneous rocks. Also present in all three suites are pyroxenites and hornblendites. For each volcanic field, a model crustal profile is proposed based on calculated or measured P-wave velocities of xenoliths and depth-Vp relationships (EGT Central Segment and Rhenish Massif traverses). The xenolith lithologies from the NHD and the Eifel show some similarities. The middle crust between the depths of about 10 and 25 km consists mainly of meta-sediments, felsic gneisses and granulites. Meta-sedimentary rock types are particularly abundant in the Eifel at depths of between about 5 and 15 km but are less common within the NHD xenolith collection. The felsic gneisses range from meta-granites to meta-tonalites (I-and S-type). Eifel meta-sediments range from meta-pelites to meta-greywackes and meta-quartzites. The NHD xenolith suite contains a few highly depleted granulite-facies meta-sedimentary fragments. At depths between 24 and 26 km, the increase in Vp from about 6.8 to 〉 8 km s−1 (28–34 km) is correlated with the presence of mafic granulites intercalated with eclogites, pyroxenites and hornblendites. Beneath North Hessia, the granulite layer problably grades into a composite eclogite-peridotite layer at the lower part of this transition zone. The crust beneath the Urach/Hegau consists largely of meta-sediments with subordinate felsic meta-igneous rocks. Most of the meta-sedimentary samples seem to be depleted in felsic components, suggesting intra-crustal differentiation by partial melting. The Urach crust contains lithologies which are similar to the outcropping Moldanubian-type para-gneisses of the Black Forest. Mafic and ultramafic xenoliths from the Urach/Hegau differ in their mineralogy and chemical composition from the Eifel and NHD mafic granulites. They represent meta-cumulates derived from alkaline magmas which intruded the base of the crust and underwent deformation and recrystallization. Petrographic and chemical differences between Urach/Hegau and Eifel/NHD are believed to reflect the contrasting styles of crustal evolution in the Rhenohercynian and the Moldanubian belts of the Variscan orogen.

Description: The flux of reactive organic carbon (C(org)) into sediments of the southern and eastern Weddell Sea was estimated by modelling measured oxygen and nitrate pore-water profiles. Highest flux of reactive organic carbon into the sediment was calculated for the shelf region (500 and 600 mmol C m-2 year-1), whereas for pelagic and continental slope sediments C(org) fluxes of less than 60 mmol C m-2 year-1 and 100-200 mmol C m-2 year-1 respectively were calculated. The oxygen penetration depth (OPD) ranged from less than 2 cm in shelf sediments to much greater than 40 cm in pelagic sediments. For the first time, sediments covered by the Filchner Ice Shelf (probably cut off from a source of primary production for a few decades) were sampled. In this area a restricted vertical flux of reactive organic carbon was expected. However, the C(org), content of these sediments was as high as that of Antarctic shelf sediments, which suggests lateral transport of organic matter. In contrast, pore-water profiles and calculated reactive organic carbon fluxes off Filchner Ice Shelf are similar to those of much deeper depositional environments (3000-4000 m water depth).

Description: 1. The salivary enzymes of the octopus Eledone cirrhosa were separated using isoelectric focusing techniques (IEF) and HPLC. 2. The use of casein zymograms allowed the detection of at least 10 caseinolytic bands in analytical IEF gels and a preliminary, based on pI values, is described. 3. There appear to be two salivary chitinases. 4. Using HPLC, it was possible to separate the most cationic of these from the proteolytic enzymes of similar pI.

Description: The Hg concentration in horned octopus was studied in relation to its biological cycle. The metal was measured in the muscle tissue of specimens of different size, sex and maturity. This species proved to be a strong accumulator of mercury, whose concentration was found to be correlated with length independently of the sex. The relationship with size was found also for the organic form. Consideration was given to the danger of frequent consumption of this cephalopod and to its use as a biomonitor of environmental mercury impact.

Description: U/Th (TIMS) and 14C (AMS) measurements are presented from two coral cores from the Easter group of the Houtman Abrolhos Islands between 28°S and 29°S on the western continental margin of Australia. The U/Th measurements on the Morley core from Morley Island cover a depth interval from 0.2 m above present sea level to 24.4 m below present sea level and comprise eleven samples. The ages vary between 6320 ± 50 a, at 0.2 m above sea level, and 9809 ± 95 a, at 24.4 m below sea level (all errors are 2σ). The mean growth rate is 7.1 ± 0.9 m/ka. The 14C dates of selected Morley core corals show that the 14C ages are ∼ 1000 a younger than their corresponding U/Th ages, which agrees with previous results. The main purpose of our 14C measurements is to be able to compare them precisely with other coral cores where no U/Th measurements are available. The U/Th measurements of the Suomi core from Suomi Island cover a depth interval from 0.05 m to 14.2 m below present sea level and consist of four samples. The ages vary between 4671 ± 40 a, at 0.05 m below sea level, and 7102 ± 82 a, at 14.2 m below sea level, with a mean growth rate of 5.8 ± 0.2 m/ka. The growth history of both cores is explained by a simple model in which the growth rates of the Morley core can be interpreted as reflecting local rates of sea level rise, whereas the Suomi core is interpreted as reflecting lateral growth during the past ∼ 6000 a. Our results indicate that sea level relative to the western margins of the Australian continent was about 24 m lower than present at about 9800 a B.P. (14C gives a date of 8500 a B.P.). Sea level then rose and reached a highstand, slightly higher than the present position at about 6300 a B.P (14C date: 5500 a). This highstand declined but was still higher than present at 4600 a B.P. This is in agreement with previous observations along the Australian coastal margins and with observations from the Huon peninsula (Papua New Guinea). Our results are very similar to theoretical numerical models, which take into consideration water loading and isostatic compensation and viscous mantle flow. In contrast, coral cores from Barbados show that corals with a 14C age of ∼ 5500 a B.P. are some ∼ 10 m b.p.s.l. We interpret the difference between the Barbados core and the Morley core as resulting from additional “flooding” of Barbados by water redistribution, due to changes in the Earth's geoid but not reflecting global sea level rise or major addition of melt waters over the past ∼ 6000 a. The difference in the geoid at Barbados between ∼ 6000 a B.P. and the present will require a refinement in the geophysical models. Precise230Th (TIMS) measurements on continental coasts will be required to provide an adequate data base for modelling deformation, flow of mantle material and sea-level height

Description: Coupling between surface water plankton and abyssal benthos was investigated during a mass development of salps (Salpa fusiformis) in the Northeast Atlantic. Cyanobacteria numbers and composition of photosynthetic pigments were determined in faeces of captured salps from surface waters, sediment trap material, detritus from plankton hauls, surface sediments from 4500–4800 m depth and Holothurian gut contents. Cyanobacteria were found in all samples containing salp faeces and also in the guts of deep-sea Holothuria. The ratio between zeaxanthin (typical of cyanobacteria) and sum of chlorophyll a pigments was higher in samples from the deep sea when compared to fresh salp faeces, indicating that this carotenoid persisted longer in the sedimenting material than total chlorophyll a pigments. The microscopic and chemical observations allowed us to trace sedimenting salp faeces from the epipelagial to the abyssal benthos, and demonstrated their role as a fast and direct link between both systems. Cyanobacteria may provide a simple tracer for sedimenting phytodetritus.

Description: An improved tectonic database for the South Atlantic has been compiled by combining magnetic anomaly, Geosat altimetry and onshore geologic data. We used this database to obtain a revised plate-kinematic model. Starting with a new fit-reconstruction for the continents around the South Atlantic, we present a high-resolution isochron map from Chron M4 to present. Fit reconstructions of South America and Africa that require rigid continental plates result in substantial misfits either in the southern South Atlantic or in the equatorial Atlantic. To achieve a fit without gaps, we assume a combination of complex rift and strike-slip movements: (1) along the South American Parana-Chacos Basin deformation zone (2) within marginal basins in South America (Salado, Colorado Basin) and (3) along the Benue Trough/Niger Rift system in Africa. These faults are presumed to have been active before or during the breakup of the continents. Our model describes a successive “unzipping” of rift zones starting in the southern South Atlantic. Between 150 Ma (Tithonian) and approximately 130 Ma (Hauterivian), rifting propagated to 38 °S, causing tectonic movements within the Colorado and Salado basins. Subsequently, between 130 Ma and Chron M4 (126.5 Ma), the tip of the South Atlantic rift moved to 28 °S, resulting in intracontinental deformation along the Parana-Chacos Basin deformation zone. Between Chron M4 and Chron MO (118.7 Ma) rifting propagated into the Benue Trough and Niger Rift, inducing rift and strike-slip motion. After Chron MO, the equatorial Atlantic began to open, while rifting and strike-slip motion still occurred in the Benue Trough and Niger Rift. Since Chron 34 (84 Ma), the opening of the South Atlantic is characterized by simple divergence of two rigid continental plates.

Description: Seabeam mapping in the central Pacific Ocean, southeast of Pitcairn Island, has revealed a number of large volcanic edifices, some of which appear to be currently active. Here we document the first isotope and trace element data obtained for dredge samples from these volcanoes which are believed to represent the present-day surface expression of the Pitcairn mantle plume. Striking linear trends in multi-isotope plots suggest the operation of a simple two-component mixing process in the genesis of these lavas with end-members of extreme EM-I and isotopically more depleted type. Isotope-trace element covariations allow limits to be placed upon the composition of the Pitcairn plume source, which is then compared with other EM-type oceanic islands. Current hypotheses for the generation of EM components are then evaluated in the light of these data. Temporal trends, similar to those seen on Pitcairn Island, are present within the seamount data, although samples equivalent to the post-shield formations on Pitcairn Island are not observed. These evolutionary trends suggest a high level origin for the depleted component rather than entrainment of asthenospheric material into a rising diapir. Three of the Pitcairn seamounts are much older, in the region of 20–25 Ma, and were probably formed in a near-ridge environment.

Description: The geochemistry of mid-oceanic ridge basalts from 86°N (Arctic Ocean) provides, for the first time, an insight into the composition of the mantle around the North Pole. Our data show the source region of the Arctic basalts to possess traces of an enrichment similar to the DUPAL signature. This is remarkable since up to now the DUPAL signature has been believed to be present only in Indian but not in Atlantic or Pacific MORB. These results also argue against a model of whole-mantle convection, in which upwelling of enriched material at the equator is balanced by downwelling of depleted material at the poles

Description: In order to characterize the sediments of the South Kolbeinsey Ridge and to determine the influence of morpho- and hydrodynamic conditions in this area, a comprehensive sedimentological investigation was combined with detailed geochemical analyses. Lithological composition and grain size are mainly controlled by the input from two different sources: the submarine, active mid-ocean ridge and Iceland. Coarse-grained volcanic material dominates in the ridge area, whereas fine-grained detritus from Iceland characterizes the adjacent basin. Further, the distribution of these sediments is largely influenced by hydrodynamic conditions and redeposition processes. Strong bottom-water currents indicated by the benthic foraminifer species Cibicides lobatulus prevent extensive deposition of fine-grained material on the top of the ridge. The ridge slope is characterized by redeposited sediments of various grain sizes. Bulk-sediment chemical analyses show element distribution patterns that are strongly correlated with the ratio of volcanic vs. detritic particle composition. This ratio reflects particle input and distribution processes. Two element associations are notable: elements coupled with (1) ridge-derived volcanic particles and (2) the detrital 〈2 μm fraction which reflects weathered material from Iceland.

Description: The oxygen isotopic composition of bulk chalk samples, the planktonic foraminifers Globotruncana and Rugoglobigerina, and the benthic bivalve Inoceramus are reported from the standard section of the Upper Cretaceous white chalk of Lägerdorf-Kronsmoor, NW Germany (Middle Coniacian to Lower Maastrichtian). The section shows the increasing impact of burial diagenesis with depth expressed by a significant negative trend in the oxygen isotopic values and increasing amounts of secondary, precipitated microspar. However, the biogenic components studied show different diagenetic characteristics. The planktonic foraminifers are completely recrystallized, whereas the prisms of Inoceramus are well preserved and only slightly overgrown by negligible amounts of secondary calcite. The original oxygen isotopic composition of the chalk is estimated on the basis of numerical elimination of the diagenetic trend and by use of a normalized carbonate content. It appears that the corrected isotopic signal of the bulk sediment, which primarily consisted of calcareous nannoplankton, significantly correlates with the isotopic composition of the Inoceramus prisms. Thus, the benthic bivalve Inoceramus and the nannoplankton probably lived in a water mass of the same isotopic composition. The Inoceramus oxygen isotope values suggest a mean temperature of approximately 16°C for the NW European Basin during the late Campanian and early Maastrichtian.

Description: In this paper we present a literature survey of the South Atlantic's climate and its oceanic upper-layer circulation and meridional heat transport. The opening section deals with climate and is focused upon those elements having greatest oceanic relevance, i.e., distributions of atmospheric sea level pressure, the wind fields they produce, and the net surface energy fluxes. The various geostrophic currents comprising the upper-level general circulation are then reviewed in a manner organized around the subtropical gyre, beginning off southern Africa with the Agulhas Current Retroflection and then progressing to the Benguela Current, the equatorial current system and circulation in the Angola Basin, the large-scale variability and interannual warmings at low latitudes, the Brazil Current, the South Atlantic Current, and finally to the Antarctic Circumpolar Current system in which the Falkland (Malvinas) Current is included. A summary of estimates of the meridional heat transport at various latitudes in the South Atlantic ends of the survey