ALBERT

Description: Marine organic-carbon-rich deposits occur where there is an ample rain of organic particulate material to the sea floor and conditions favorable to its preservation. It was originally thought that the accumulation of organic carbon (Corg) was dependent mostly on anoxic conditions at the site of deposition; two such environments, the stagnant basin and the O2 minimum, were often cited as models. High productivity in the overlying waters has become recognized to be of greater importance. In an overall evaluation of burial of Corg in marine sediments, it is apparent that terrigenous input of organic matter is the largest source, followed by marine organic matter fixed in highly productive coastal areas receiving nutrients from land. In terms of rich accumulations of marine organic matter most likely to generate petroleum, areas of ocean upwelling along continental margins are most significant.

Description: The role of cephalopod haemocyanins in oxygen transport is analysed in the light of the coordination of metabolism, acid‐base regulation and gas exchange processes. Results obtained in squid, the most active among cephalopod species, indicate that the pH dependence of their haemocyanin supports a Po2‐buffer function for the pigment. The release of base equivalents from the tissue during aerobic exercise and the minimal release of protons during anaerobic octopine formation protect arterial pH and, thus, oxygen binding. The extent of respiratory acidification and haemocyanin deoxygenation on the venous side is higher in blood returning from the mantle than from the head. In vivo blood gas measurements reported for squid and for other cephalopod species support the conclusion that CO2 accumulation and respiratory acidification of the blood occur in excess of the effect expected from the consumption of haemocyanin bound O2 and RQ values derived from protein catabolism. This suggests that a considerable fraction of the oxygen consumed by the animal enters via the skin, especially in the mantle. Model calculations demonstrate that skin O2 uptake in the mantle increases during activity in squid. In other cephalopod species like cuttlefish, the special process of arterial CO2 binding to oxygenated haemocyanin and its release during venous deoxygenation may provide the excess CO2 required for venous acidification. All of these processes allow the classical Bohr effect to function supporting oxygen loading at the gills and oxygen unloading in the tissues. The large pH‐dependent cooperativity and the Bohr effect combine to maximize the Po2‐buffer function of the respiratory pigment. These adaptations probably evolved after the ancestors of modern cephalopods lost their shells and locomotor activity assumed a greater role in their lifestyle.

Description: A number of reproductive indices were compared with a subjective maturity scale for assessment of Loligo forbesi maturity. The ratio between nidamental gland length and mantle length corresponded well with female maturation, as did the ovary mass-soma mass and nidamental gland mass-soma mass ratios. For males, the ratio between spermatophoric complex mass and somatic mass was found to be the most suitable for maturity assessment. The timing of recruitment and maturation of L. forbesi in Irish waters was described from the size and maturity of squid in commercial landings in the south of Ireland during the years 1991–1993. Immature squid first appeared in commercial catches in July and August, and this represented the main period of recruitment. A second period of recruitment was apparent in December 1991, but was not identified in the 1992–1993 season. Mature females were present in the commercially exploited population between November and April, with a small number also found in the summer. The abundance of egg masses was used to indicate timing of spawning. Egg masses recovered from the Cork coast indicated that peak spawning occurred during the winter months, but continued on a small scale for much of the year.

Description: Some deep water squids are known to achieve neutral buoyancy by storing ammonium in their body tissues. The Cranchiidae use a unique coelomic cavity to store ammoniacal fluid; in 15 other families, ammonium appears to be sequestered in either vacuoles in the active body tissues or in a gelatinous outer layer. The hypothesis that these squids form a single lineage is here reconsidered through reviews of morphological characters that could support this hypothesis and physiological mechanisms that could contribute to the repeated evolution of ammonium storage. No readily apparent character identifies all ammoniacal squids as belonging to a single lineage, although 5 families of tissue ammoniacal squids appear to be monophyletic. If the elaborate funnel locking apparatus of this group arose within the clade, it is not homologous with that in other taxa, refuting a basis on which close relationships were suggested for ammoniacal squids. Given the limited data available, we question whether some squids considered to be ammoniacal may develop these characters as a result of senescence. Squids are all thought to derive energy from amino acid catabolism, produce large quantities of ammonia and have very low blood pH's which effectively remove ammonia from cells that produce it. They also minimize H+ ion transfer between muscle cells and blood. These features may be important preadaptations for ammonium storage. Given the physiological data, and the absence of morphological evidence supporting monophyly, we argue that ammoniacal squids be best considered to be a polyphyletic group, evolved in parallel.

Description: Horizontal starch gel electrophoresis was employed to investigate levels of genetic differentiation between 13 samples of the neritic squid species Loligo forbesi Steenstrup obtained from throughout the majority of its known geographical range. Six enzyme loci identified in a preliminary study as being polymorphic were screened for variation between samples. No significant differences in allele distribution were detected between any of the samples obtained from the Faroe Bank in the north to Lisbon in the south, suggesting that squid throughout this range in the vicinity of the continental shelf are able to maintain panmixia, and effectively belong to a single population sharing a common gene pool. No clinal variation in allele distribution was detected throughout this range, a result which complements the findings of a detailed morphological companion study of the same individuals. Comparison of this homogenous European continental shelf population with squid from the Azores revealed highly significant (P〈0.01) differences in allele distribution at five of the six polymorphic enzyme loci studied. A genetic identity value (I) equivalent to 0.93 over 33 loci was obtained. Analysis of F-statistics suggested migration rates between sites to be as low as one individual per five generations, a rate deemed insufficient under most models to prevent divergence by random genetic drift. The large distance and oceanic depths separating the Azores from continental Europe seem to present an effective barrier to gene flow to L. forbesi, a squid belonging to a family considered to be confined in distribution to relatively shallow, near coastal waters. The two populations of squid in the Azores and along the European continental shelf currently both ascribed to L. forbesi should therefore probably best be regarded as relative subspecies.

Description: Beak lengths (lower rostral length and upper rostral length) were taken for a sample of Moroteuthis ingens which were captured on the Chatham Rise, New Zealand. Beak lengths were plotted against both mantle length and wet weight to determine the relationship between these parameters for future use in biomass estimates in predator analysis. Although M. ingens is markedly sexually dimorphic, with females reaching 5 times the weight of males, there was no obvious sexual dimorphism in either lower or upper rostral length. This resulted in sex-specific relationships between both LRL and mantle length, LRL and weight; and URL and mantle length, and URL and weight. Males appeared to have a curvilinear relationship between beak length and mantle length and beak length and weight (even for log-transformed data). There was also considerable spread in the data in the plot between beak length and weight for females of similar weight. These characteristics of the data makes biomass estimates based on rostral length measurements for this species difficult. Other beak parameters may prove more useful for estimating biomass of M. ingens.

Description: Body size at sexual maturity, egg-size distributions, and potential reproductive output have been estimated for female and male squid, Loligo forbesi Steenstrup, off the west coast of Scotland. Two size modes at maturity were found in both sexes, but separation into size cohorts was more pronounced in males (180 and 350 mm mantle length, ML). Preliminary ageing studies based on statolith ring-counts suggest that these size modes are not due to different age groups at breeding. Females have a single size mode of mature eggs in the proximal oviduct, but may have at least two size modes of eggs within the ovary. This finding is interpreted as evidence of batch-spawning in this squid. There was a weak relationship between total egg numbers (range 1000 to 16000) and body size (range 196 to 318 mm ML) and between mature egg size and body size. Males showed a strong positive relationship between spermatophore length and body length but a weak relationship between total number of spermatophores and body size. The results are discussed in the context of flexibility of breeding strategies in the loliginids and variety of life-cycle patterns.

Description: This study assesses the potential of the tropical loliginid squid Photololigo sp. to lay multiple batches of eggs and examines changes in somatic growth during reproduction. Histological analysis of the ovary and the relative size of the oviduct to mantle weight and ovary weight were used to determine the potential for multiple spawning. Ovaries of mature females always had immature and mature oocytes present, suggesting that not all the oocytes were maturing simultaneously and that multiple batches of eggs were being produced. Furthermore, poor correlations of oviduct weight with body size and ovary weight indicated that mature oocytes were not accumulating in the oviduct for a single spawning event. Both these observations supported the hypothesis that Photololigo sp. has the potential to lay multiple batches of eggs throughout its life. Specific growth rates, length-weight relationships, relative growth of somatic and reproductive tissue and microscopic assessment of muscle tissue were compared between immature and mature females. Growth rates of immature females were almost twice as fast as those of mature females. Mature females also had no large muscle fibres present, suggesting that energy for reproduction was mobilised from the muscle tissue.

Description: The quick development of the skull structure is of vital importance to animals during the early stages of life given that here in are located the governing center and the mechanisms which make feeding possible. However, the rhythm of growth changes thoughout the life cycle, a process which is particularly manifest in the proportionate head/body growth. The mouth structures grow proportionately to head growth. These accentuated changes in the anatomy of the animal could be reflected in its behavioural pattern (migrations between two areas in the case of some species and significant changes in diet connecting to these migrations). Scomber japonicus (Pisces. Scombridae) and Illex coindetii(Cephalopoda, Ommastrephidae) both undergo significant changes in the rhythm of growth of their respective mouth structures when they reach around 13-15 and 14-20 cm of total body length (mantle length in cephalopods) respectively. In Illex coindetii there are also differences by sex, being the changes of growth at 15 cm in males and around 20 cm in females. In both of these species, this change in the rhythm of growth implies a significant variation in dietas the consequence of a shift of habitat.

Description: Two species of third-stage larvae of the family Anisakidae are described from the Japanese common squid (Todarodes pacificus Steenstrup) from the Sea of Japan. The larvae of 1 of them, Anisakis simplex (Rudolphi, 1809), commonly occur encapsulated in the viscera of squid, whereas those of another 1, identified as Lappetascaris sp., are found free in the mantle musculature. The latter, characterized by the presence of a very long ventricular appendix, a conspicuous esophageal gland, and the structure of the cephalic end (presence of sclerotized supports of lip anlagen), previously were reported by various authors as members of the genera Contracaecum, Thynnascaris, or Hysterothylacium. It appears that the larvae form the mantle of squid belong to a hitherto undescribed Lappetascaris species whose adults parasitize an, as yet unknown, predatory marine fish.

Description: Cephalopod research in Thailand has been underway since 1978 with the goal of developing successful mass-culture techniques. Results of mass cultivation have demonstrated several favorable aquaculture characteristics of cephalopods, i.e., high growth rates, short life cycle, high fecundity, high hatching rate, and absence of true larval stages. Three species are being cultured: bigfin squid, Sepioteuthis lessoniana; spineless cuttlefish, Sepiella inermis; and pharaoh cuttlefish, Sepia pharaonis. They were listed in declining order of production and suitability for aquaculture. About 2 million cephalopod seed have been produced and released annually since 1990 to enhance natural stock. Biohistory, behavior and water quality requirements are also being studied in order to supply basic information for aquaculture. However, there are also several obstacles, particularly development of cost-effective feeds.

Description: We establish the relationship between shell oxygen(6le0) and carbon (S13C) isotopic composition and size and thickness for the planktonic foraminifers Orbulina universa and Neogloboquadrina dutertrei (size only). The degree to which the stable isotopic composition of individual shells correlates with shell size limits their applicability to paleoenvironmental reconstructions and must therefore be examined carefully. We selected shelis from four intervals from a western and an eastern equatorial Atlantic core corresponding to the glacialhnterglacial extremes of the last 150,000 years (isotope stages 1, 2, 5e, and 6). We estimate the shell thickness of 0, universa using a mathematical relationship between the geometry and physical properties of a calcite sphere. Thickness measurements on selected shells of this species confirm that the calculated thickness, once it has been corrected for shell porosity, is equivalent to the measured thickness. There are no consistent trends between 0. universa 6l80 or 613C values and shell size or thickness for the size range 450-900 pm. For N. dutertrei, there are no systematic fluctuations between shell 6l80 and size between 450-700 pm. N. dutertrei shells larger than 500 pm show no 613C : size relationship. We are confident that the stable isotopic variability contained in 0. universa (450-900 pm) and N. dutertrei (〉500 pm) assemblages analyzed does not fluctuate with differences in shell morphology. The stable isotope data from these size ranges can thus be confidently used for paleoenvironmental reconstructions.

Description: A non-Fickian physico-chemical model for electrolyte transport in high-ionic strength systems is developed and tested with laboratory experiments with copper sulfate as an example electrolyte. The new model is based on irreversible thermodynamics and uses measured mutual diffusion coefficients, varying with concentration. Compared to a traditional Fickian model, the new model predicts less diffusion and asymmetric diffusion profiles. Laboratory experiments show diffusion rates even smaller than those predicted by our non-Fickian model, suggesting that there are additional, unaccounted for processes retarding diffusion. Ionic diffusion rates may be a limiting factor in transporting salts whose effect on fluid density will in turn significantly affect the flow regime. These findings have important implications for understanding and predicting solute transport in geologic settings where dense, saline solutions occur.

Description: Alkaline volcanic rocks including nephelinites, basanites and trachybasalts dredged from the volcanic pedestal of Rakahanga Atoll and from a volcanic edifice with 100 satellite volcanoes at the eastern edge of the Manihiki Plateau, ca. 40 km southwest of the atoll, fall well within the category of EM-type ocean island basalts. They indicate a hotspot involvement during the formation of the plateau basement. The rocks are thought to be products of explosive eruptions which took place subaerially or in shallow water in the Aptian. The volcanoes, together with other volcanic eruption centers, most likely were responsible for the formation of the 230 m thick volcaniclastite layer which rests on the basement for at least 5000 km2 of the eastern part of the Manihiki Plateau. Erosion has prevented any substantial sediment cover on the volcanic cone field and most of the slope of Rakahanga and thin pelagic limestones were deposited instead at least since the Maastrichtian.

Description: The acoustic response from areas of varying nodule abundance and number densities in the Central Indian Ocean has been studied by using the echo peak amplitudes of the normal incidence beam in the Multibeam Hydrosweep system. It is observed that in areas of higher nodule abundance, the acoustic response is more deterministic. The coefficient of variation of the echopeak amplitude is observed to be the highest for areas with medium nodule abundance and number densities.

Description: A model is presented which tests the representation of the maturity process in terms of gonadosomatic indices (GSI) in chokka squid Loligo vulgaris reynaudii. It assumes that the true maturation process is reflected by the results of histological investigation, which cannot be used in large-scale ecological work in the field. However, the maturity scales used in ecological studies define some morphological categories which can be linked directly to microscopic development. Therefore, the overlap of GSI ranges for each morphological maturity category may be used to judge how well the GSIs represent the histological stages. Results have shown that the overlap is large and that GSI cannot be recommended as adequately reflecting the maturation process in squid. A morphological scale of maturity with possible broad applications in exploited families of squid is proposed as a better representation of the maturation process than GSI.

Description: Morphological differences between paralarvae of two loliginid squid species common in southern African waters (Loligo vulgaris reynaudii and Lolliguncula mercatoris) are described. The differences are: Loligo — "cheek patches" consisting of four dark chromatophores, nine large dark dorsal chromatophores on the mantle, tentacular clubs broad and much wider than tentacle stalks, proximal row of three club suckers with others tetraserial, suckers large enough to appear crowded on the club surface; Lolliguncula — "cheek patches" with three dark chromatophores, two pairs of" large, dark dorsal chromatophores on the mantle, tentacular clubs narrow, proximal club suckers arranged in three pairs, suckers small, not particularly crowded. Relationships with other myopsids are briefly discussed.

Description: The natural feeding of 485 Octopus mimus (164 to 3088 g) was studied in relation to the species' life cycle and environmental seasonal variations off the north of Chile from autumn 1991 to summer 1992. Analysis of digestive-tract contents revealed that O. mimus preyed upon 25 different prey items belonging to five zoological groups (Teleostei, Mollusca, Crustacea, Echinodermata and Polychaeta). Cannibalism was only occasional. The results indicate that the diet and food intake of this species are significantly affected by sex and maturation. Senescent individuals ingest a small amount of food, and their diet is mainly based on small, not very motile prey. The food intake, expressed as body weight, of non-senescent individuals is higher in females than in males. Seasonal changes in sea-water temperature seem to be followed by adjustments in food intake. Like other Octopus species, O. mimus appears to be an opportunistic predator.

Description: The relationship between reproduction and condition was studied in a 15 mo sample of 919 maturing, mature and post-spawning female Octopus mimus (388 to 3714 g) caught in Iquique (North Chile). O. mimus is a semelparous species, with reproduction taking place all year round. Investment in reproductive tissues was, on average, 9.9% of mature female body weight, independent of season. However, somatic growth during maturation was dependent on season and varied between 26 and 63% of the whole-body growth in weight. The condition of females did not vary markedly until spawning, although seasonal variations were apparent, winter being the most unfavourable. Condition deteriorated dramatically after spawning, during parental care of the eggs. During this period, somatic-tissue depletion, mainly from the muscles, was 〉25% of the total body weight of mature females. The fecundity of O. mimus was probably limited by the costs associated with parental care of the eggs.

Description: Logs collected while drilling measured density in situ, through the accretionary prism and decollement zone of the northern Barbados Ridge. Consolidation tests relate void ratio (derived from density) to effective stress and predict a fluid pressure profile, assuming that the upper 100 m of the prism is at a hydrostatic pressure gradient. The calculated fluid pressure curve rises to 〉90% of lithostatic below thrusts in the prism, presumably due to the increase in overburden and lateral tectonic loading. Thin (0.5–2.0 m) intervals of anomalously low density and resistivity in the logs through the basal decollement zone suggest dilation and perhaps hydrofracturing. A peak in hydraulic head in the upper half of the decollement zone requires lateral influx of fluid, a conclusion consistent with previous geochemical studies. Although the calculated fluid-pressure profile is model dependent, its inherent character ties to major structural features.

Description: Recent data from research cruises and explorator fishing in the Antarctic Polar Frontal Zone (APFZ) of the Scotia Sea, together with data from dietary studies of Antarctic vertebrate predators, have revealed a large, previously overlooked trophic system in the Southern Ocean (Fig. 1). The upper trophic levels of this open-ocean epipelagic community are exceptional in that they contain no fish species. Fishes are replaced by cephalopods, including the ommastrephid squid, Martialia hyadesi. This squid preys on mesopelagic m.yctophids (lanternfish), which feed largely on copepods. We identify here a geographically distinct, Antarctic, open-ocean food chain which is of importance to air breathing predator species but where Antarctic krill, Euphausia superba, is absent. This system is probably prevalent in areas of higher primary productivity, especially the Scotia Sea and near the peri-Antarctic islands. Squid stocks in the APFZ may have potential for commercial exploitation, but they, and the predators they support, are likely to be sensitive to overfishing. Squid have a short, semelparous lifecycle, so overfishing in a single year can cause a stock to collapse.

Description: The first record of Potamothrix bedoti (Piguet, 1913) in Norway is from the eutrophic lake Ärungen 34 m a.s.1. (59°45’N, 10°41’E) in the county of Akershus, where 31 mature specimens were collected in the littoral zone from 1.0 to 3.0 m depth in silt and clay Sediments. In Scandinavia, the species is also known from Sweden. Six mature specimens of Haber speciosus (Hrabe, 1931) were found in the northem part of the oligotrophic lake Maridalsvannet 149 m a.s.L (59°59’N, 10°47’E) in the county of Oslo. The worms were found in the littoral zone on sandy bottom with scattered Isoetes sp. Vegetation at approximately 1.5 m depth. The species has earlier not been recorded from Scandinavia.

Description: A 900-m-thick section of tuffaceous sedimentary rock, vitric fallout tuff, and ash-flow tuff is well exposed along Trapper Creek in south-central Idaho. This section provides nearly continuous exposure through the fill of the Goose Creek basin, a major north-trending Miocene extensional basin located along the southern margin of the Snake River Plain volcanic province (SRPVP). Some 51 separate units of vitric fallout tuff are recognized in the Trapper Creek section. Petrographic and chemical characteristics of these vitric tuffs indicate that most are from SRPVP sources. New 40Ar/39Ar laser-fusion dating, along with prior isotopic age determinations, show that the Trapper Creek tuffs span the period ca. 13.9 – 8.6 Ma. Chemical correlation indicates that fallout tuffs in the central part of the Trapper Creek section (12.5 – 10.0 Ma) are from sources in the Bruneau-Jarbidge volcanic field of the SRPVP centered ≈100 km west of Trapper Creek. Underlying fallout tuffs may have had sources in the Owyhee-Humboldt field of the SRPVP centered ≈200 km west of Trapper Creek, while overlying fallout tuffs, interlayered with several ash-flow tuffs, had a relatively proximal source, possibly in the proposed Twin Falls volcanic field centered ≈60 km north of Trapper Creek. The Trapper Creek tuffs provide insight into the characteristics of explosive silicic volcanism within the SRPVP during middle – late Miocene time. From ca. 13.9 to ca. 9.5 Ma, major eruptions (those depositing ≥1.5 m of fallout tuff) were frequent (about one event per 200 k.y.); their products display a trend toward the eruption of progressively less evolved, higher temperature silicic magma after 12.5 Ma. This trend to higher temperature eruptions, termed the Cougar Point “flare-up,” culminated in the eruption of high-temperature (≈1000°C), plagioclase-rich magma during the period 10.5 – 9.5 Ma. In contrast to these eruptions, later (〈7.0 Ma) major silicic eruptions within the SRPVP were characterized by the lower temperature (≈850°C) of the erupted magma and by the longer intervals (about one event per ≈500 – 600 k.y.) between eruptions. Variations in the character of SRPVP explosive silicic eruptions may reflect changes in the structure, composition, or state of stress in the crust beneath the eastward propagating SRPVP, or, perhaps, changes in the Yellowstone hot-spot plume that may drive the SRPVP volcanism.

Description: This chapter discusses the rates of protein synthesis in fish. Protein synthesis can be viewed at a number of levels. Whole-animal values can be integrated into the descriptions of assimilation/growth or assimilation/metabolism patterns in different fish species and is the focus of the chapter. The measurement of protein synthesis rates in body organs and tissues can provide information on the extent to which differences exist among various tissues and offer a challenge in understanding the integration of organ metabolism into whole animal physiology. The majority of methods for estimating protein synthesis measure the flux of an amino acid or nitrogen. This involves the use of tracer substances—that is, amino acids labeled with an isotope, which are given in a single dose or by continuous infusion. The measurements, parameters, and formulae that are commonly employed in the studies of protein growth, synthesis, and degradation are described in the chapter. It discusses the mechanism of nutrition and protein synthesis in the fish and explains the impact that protein synthesis has upon the rates of oxygen consumption.

Description: The tissue of 31 demosponge and 7 hexachnelhd species was analyzed for its composition of organic and lnorganic matter With one excephon (Hahclona cf gausaana) inorganic matter i e n~ostly the siliceous skeleton, accounted for most of the dry weight, varying between about 60 and 95%dry wt There were no general trends in the ratio of organic to inorganic matter within sponge orders or genera, and within one species, the ratio could vary between stations For one of the hexactinellids Bathydorus spmosus, several size classes were analyzed and there was no systematic change in the organic inorganic matter ratio w t h specimen size For some species the results from the Weddell Sea sponges are in good agreement with earlier data from McMurdo Sound The low organic matter content in Weddell Sea sponges mphes that sponge biomasses are much lower than hitherto assumed on the basis of then high abundances and large sizes In consequence Antarctic sponges despite their ubiquitousness, may only channel a m n o r fractlon of the general bentho-pelagic flow of matter and energy and their maln role in the ecosystem is likely structural rather than dynamic

Description: Auf- und Abbauprozesse und Bedeutung deponierter Skelettelemente für die Struktur der Lebensräume

Description: During 5 consecutive summer seasons (1990 to 1994) both Aureliaaurita medusa and mesozooplankton abundances were investigated at 2 stations in the Kiel Bight (western Baltic Sea). Stocks of medusae varied considerably between the years, with median abundance of 1 and 0.3 ind. 100 m-3 in 1990 and 1991, 3 and 4 ind. 100 m-3 in 1992 and 1994, but 9 ind. 100 m-3 in 1993. Significant differences in the mesozooplankton stock and community composition were observed in 1993 when compared with the year of rather low Aurelia abundance (1991). Total zooplankton and copepod numbers both exhibited an inverse relationship with the abundance of medusae and were thus considerably lower in 1993 than in 1991. However, not all copepod species were affected by A. aurita. Pseudo- and Paracalanus spp. and Oithonasimilis showed dramatically reduced stocks in the bloom year when compared with the medusa-poor situation, but no significant changes were found for Centropageshamatus and Acartia spp. Also other zooplankton groups with the exception of bivalve larvae were reduced by the medusae. The differential response of zooplankton to varying abundance of medusae led to a shift in the trophic structure of the zooplankton community. Fine-filter feeders and raptorial feeders were much more important in years when medusae occurred in low densities, whereas coarse-filter feeders dominated in the opposite situation.

Description: The modern ocean is comprised of four units: an equatorial belt shared by the two hemispheres, tropical subtropical anticyclonic gyres, mid-latitude belts of water with steep meridional temperature gradients, and polar oceans characterized by cyclonic gyres. These units are separated by lines of convergence, or fronts: The Early Cretaceous ocean closely resembled the modern ocean. The developing Atlantic was analogous to the modern Mediterranean and served as an Intermediate Water source for the Pacific. Because sea-ice formed seasonally in the Early Cretaceous polar seas, deep water formation probably took place largely in the polar region. In the Late Cretaceous, the high latitudes were warm and deep water moved from the equatorial region toward the poles, enhancing the ocean's capacity to transport heat poleward. The contrast between surface gyre waters and intermediate waters was less. -from Author

Description: Age and growth of the large oceanic squid Thysanoteuthis rhombus were estimated by statolith increment analysis of 72 specimens [mantle length (ML) ranging from 25 to 805 mm] and reproductive biology was studied on 162 T. rhombus (ML 150 to 850 mm) captured in the eastern tropical Atlantic and southwestern Pacific between 1976 and 1990. The maximum ages found in our samples were observed in a mature female of 750 mm ML (305 d) and in a mature male of 770 mm ML (309 d). The life span of T. rhombus was estimated to be about 1 yr; males and females matured at age 6 to 8 mo. T. rhombus is one of the fastest-growing squids: by age 300 d, they reached 750 to 800 mm ML and 17 to 17.5 kg body weight (BW). The increase in both ML and BW during ontogenesis was best fitted by a logistic growth curve. T. rhombus has high potential fecundity (up to 4.8 million oocytes), but a rather small maximum volume of oviducts (up to 140000 eggs) and egg masses (35000 to 75000 eggs). It is suggested that T. rhombus is an intermittent spawner with multiple filling and evacuation of oviducts. The main function of the (for squid) unusual behaviour of T. rhombus, i.e. living in pairs consisting of a male and female, is reproduction and is optimal given the low density of T. rhombus populations and low active movement of squids.

Description: There is considerable discussion about the nature of the health metaphor as applied to ecosystems. One does not need to accept the analogy of ecosystem as 'organism' to reap insight into the diagnosis of ecosystem ills by applications of approaches pioneered in the health sciences. Ecosystem health can be assessed by the presence or absence of signs ecosystem distress, by direct measures of ecosystem resilience or counteractive capacity, and by evaluation of risks or threats from human activity and natural forces which may decrease the supply of ecological services. The focus of this essay is on what is and what is not implied by the ecosystem health metaphor. It also elaborates a research agenda for this emerging transdiciplinary science. One can argue that beyond the metaphor is the potential for systematic diagnosis of ecosystem ills, develop- ment of indicators of ecosystem health, development of early warning indicators of ecosystem dysfunction, development of diagnostic protocols and preventive strategies for maintaining ecological services.

Description: In the middle of the Cretaceous period the climatic zonation of the Earth differed from the present zonation. During that time, the polar regions were free from permanent glaciation and permafrost. Episodic glacial deposits of the Middle Cretaceous indicate only short cooling periods, which locally resulted in the seasonal freezing of seas. The temperate character of the high-latitude climate is evident from the composition of Middle Cretaceous vegetation and intense coal accumulation as well as occurrences of thermophilic insects and dinosaurs. Accordingly, this peculiar climate of the mid-Cretaceous was of the temperate, high-latitude type. It had distinct seasonal variations in insolation and temperature conditions that changed from moderately cool to moderately warm (polar nights and days). As indicated by the types of vegetation; thermophilic insects; abundant dinosaurs; and the widespread distribution of laterite, bauxite, kaolin, and coal deposits, the conditions in the middle latitudes of both hemispheres corresponded to a warm humid climate. Arid belts were also typical of the mid-Cretaceous Earth. During the Aptian, they occupied nearly all of the low-latitude zones and some provinces within the middle latitudes. In subequatorial zones, traces of the humid Aptian climate are episodic and occur only in the northeastern Arabian plate. The humid climatic belt near the equator was formed later, during ~he Albian-Turonian interval; it was confined to the western Gondwanan continents only. Its appearance seems to be related to the opening of the South Atlantic Ocean.

Description: The genus Illex is likely to constitute a large portion of the annual world ommastrephid squid catches (Roper et al, 1984), even though specific official statistics are difficult to obtain. The broad-tail short-fin squid Illex coindetii is a widespread species ranging from the western to the eastern Atlantic (Roper et al., 1984) and east through the whole Mediterranean Sea (Mangold & Boletzky, 1987). Usually a by-catch of important fisheries, it is caught mainly by trawlers. Although its economic value is lower than that of other squid species (i.e. Loligo spp.), in the Sicilian Channel Illex coindetii may represent a valuable resource due to its abundance. In Italian waters, the available statistics (Cingolani et al., 1986) report that 2680 tonnes of ommastrephid squid were landed in 1982 (0.5% of the total landed catch). The main component of these was landed in Sicily (2183 tonnes), a consistently large part of which was no doubt Illex coindetii (Ragonese & Jereb, 1992). The catches came mainly from southern Sicilian waters (Sicilian Channel) where one of the major Mediterranean landing places is in Mazara del Vallo. Large trawlers (up to 200 gross tonnage) usually carry out long fishing trips (15–20 d), and Illex coindetii is caught mainly by those targeting Parapenaeus longirostris and Merluccius merluccius (Jereb & Ragonese, 1991).

Description: Age and growth of the large oceanic squid Thysanoteuthis rhombus were estimated by statolith increment analysis of 72 specimens [mantle length (ML) ranging from 25 to 805 mm] and reproductive biology was studied on 162 T. rhombus (ML 150 to 850 mm) captured in the eastern tropical Atlantic and southwestern Pacific between 1976 and 1990. The maximum ages found in our samples were observed in a mature female of 750 mm ML (305 d) and in a mature male of 770 mm ML (309 d). The life span of T. rhombus was estimated to be about 1 yr; males and females matured at age 6 to 8 mo. T. rhombus is one of the fastest-growing squids: by age 300 d, they reached 750 to 800 mm ML and 17 to 17.5 kg body weight (BW). The increase in both ML and BW during ontogenesis was best fitted by a logistic growth curve. T. rhombus has high potential fecundity (up to 4.8 million oocytes), but a rather small maximum volume of oviducts (up to 140 000 eggs) and egg masses (35 000 to 75 000 eggs). It is suggested that T. rhombus is an intermittent spawner with multiple filling and evacuation of oviducts. The main function of the (for squid) unusual behaviour of T. rhombus, i.e. living in pairs consisting of a male and female, is reproduction and is optimal given the low density of T, rhombus populations and low active movement of squids.

Description: In the Neil Brown Instruments' MKIIIB-CTD (conductivity-temperature-depth profiler), the system's digital outputs for the three basic measurements of temperature, conductivity and pressure typically show some small amplitude deviations from smooth calibrations which should be corrected for to achieve high accuracies, as required, e.g. within the Hydrographic Program (WHP) of the current World Ocean Circulation Experiment (WOCE). These deviations show up as (i) a strong nonlinearity or even discontinuity of several mK close to 0°C in temperature output leading to too high subzero temperatures; (ii) a jump of order 0.002 mS cm−1 in conductivity output when passing the half-range value 32.768 mS cm−1, which causes jumps in the relation of potential temperature and salinity; and (iii) errors in pressure measurements of up to 4 dbar due to mechanical hysteresis and both static and dynamic responses to temperature changes. The existence of these effects is demonstrated, and methods to reduce the associated errors are suggested.

Description: A new species of rhodaliid siphonophore, Archangelopsis jagoa sp, nov., is described from three specimens collected at depths between 250 and 370 m in the Gulf of Akaba, Red Sea, by the submersible JAGO. Comparisons are made with the established species of that genus and observations, both in situ and on the living animals in captivity, are reported.

Description: Based on various lines of evidence such as the widespread occurrence of basalts, pumice, volcanic glass shards and their transformational products (zeolites, palagonites, and smectite-rich sediments), we suggest the presence of a volcanic province in the Central Indian Basin (CIB). In addition to the rocks studied, the occurrence of many morpho-tectonic features such as seamounts, abyssal hills and major fracture zones at 73 degrees E, 75 degrees 45'E and 79 degrees E, have helped in correlating and in deciphering the source of the rock types. Further, the large manganese nodule fields in the CIB are seen to occur in conjunction with the volcanic materials, since the latter forms nuclei and substrates for ferromanganese deposits. It is concluded that a spatial relation exists between the occurrence of the volcanic materials and the ferromanganese deposit in the CIB

Description: From the Gulf of Aden along a transect to the central-northern Red Sea the abundance and taxonomic composition of metazoan plankton was studied during the southwest monsoon period (summer 1987). Samples were taken with 0.055 mm mesh nets down to a maximum depth of 1050 m. In the epipelagic zone, a distinct decrease in total plankton abundance was observed from south to north, which was much more pronounced in biomass (by a factor of up to 10) as compared to numbers (by a factor of 2). This could partly be explained by differences in the taxonomic and/or size composition of the planktonic fauna. Among non-calanoid copepods, 40 out of 75 species or taxa investigated decreased in abundance from south to north. Sixteen of these species were completely absent in the central-northern area. Nineteen species or taxa, however, showed the opposite feature of a higher abundance in the central-northern Red Sea. The stations were grouped according to similarities in the taxonomic composition of non-calanoid copepods in the epipelagic zone. The following 3 geographical regions could be separated: (1) Gulf of Aden and Strait of Bab al Mandab; (2) southern Red Sea; and (3) central-northern Red Sea. In the meso- and bathypelagic zones, regional differences were not evident. The results are discussed in relation to hydrographic conditions during summer 1987.

Description: A spring investigation of the phytoplankton in the western Alboran Sea (Mediterranean) was undertaken using chlorophyll and carotenoid biomarkers to characterize the community in the water column and in drifting sediment traps set at 100 and 200 m. During 2 drifter experiments, calm and sunny conditions induced a progressive thermal stratification that reduced pigment sedimentation into deeper water and confined the phytoplankton to the surface layer, resulting in an increase in chlorophyll biomass. 19'-Hexanoyloxyfucoxanthin (prymnesiophytes) and chlorophyll b (chlorophytes, prasinophytes, prochlorophytes) were the major accessory pigments, while fucoxanthin, alloxanthin and peridinin indicated the presence of diatoms, cryptophytes and dinoflagellates, respectively. The proportional contribution of each algal group to the chlorophyll a (chl a) biomass, as derived from multiple regression analysis, revealed that prymnesiophytes, cryptophytes and the green algal group collectively accounted for at least 75% in the upper 100 m, emphasizing the importance of the nanophytoplankton. Phaeopigments, dominated by phaeophorbide a2, were the main pigments observed in sediment traps, although chl a, fucoxanthin and 19'-hexanoyloxyfucoxanthin were detected in smaller concentrations as well as traces of chlorophyll b (chl b). In deep water, fucoxanthin and 19'-hexanoyloxyfucoxanthin were the only accessory pigments present while total phaeopigment/chl a molar ratios 〉1 reflected the active transformation of fine phytogenic material at depth. High particulate organic carbon (POC)/chl a ratios (〉100 in surface water; 〉1000 in deep water) suggested that phytoplankton was a relatively small component of the total carbon biomass down the water column. Using simple budget calculations, we determined that 58 to 65% of the chl a produced in the upper 100 m accumulated in the water column over both experiments. During Expt 1, 29% of the chl a sedimented out, mostly as phaeopigment, at 100 m (24%), and 6% was degraded to colourless residues in the water column. In contrast, only 12% of the chl a sedimented in Expt 2, while 20% was degraded to colourless residues.

Description: A fourfold subdivision of the NP10 zonal interval is proposed based on calcareous nannofossil biostratigraphic events associated with lineages in the genus Tribrachiatus. This subdivision, based on a detailed analysis of DSDP Site 550, provides a reliable means of determining relative completeness of upper Paleocene-lower Eocene sections in deep-sea as well as epicontinental settings. By means of calibration to magnetochronology it affords a fine chronologic resolution for Biochron NP10. Correlation of planktonic foraminiferal Zones P5 to P6b to the proposed subzonal scheme as seen in Hole 550 is presented. Carbon isotopic trends in the four NP10 subzones as seen in Hole 550 are also given. The proposed subdivision rests largely upon the range of a new species described herein, Tribrachiatus digitalis. This species has a broad geographic distribution and a restricted range in Zone NP10. The concept of Zone NP10 was recently modified to conform to the proposal that Rhomboaster cuspis and Tribrachiatus bramlettei are synonymous, a view that is not shared here. The structural differences between nannoliths assigned to Rhomboaster and Tribrachiatus are clarified and it is shown that R. cuspis and T. bramlettei are discrete taxa. The main consequence of the new zonal scheme is that it allows the determination of a level equivalent to the base of the London Clay Formation in marine sections outside of northwestern Europe. It is inferred from this that the age of the basal transgression of the London Clay Formation (Walton Member) is 54.37 Ma.

Description: The species, distributions and abundances of squids in the Southern Ocean are difficult to assess by conventional oceanographic means. The study of the food and feeding ecology of squid-eating predators such as procellariiform seabirds appears to be a supplemental way to collect useful information on cephalopod biology. Regurgitations were collected from 52 chicks of the black-browed albatross Diomedea melanophrys at Kerguelen Island in February 1994. Cephalopod remains were removed and identified by means of beaks, gladius and mantle. Squid beaks of the family Ommastrephidae amounted to 55 % (n = 348) of the accumulated squid beaks. They were also those most often regurgitated in association with partially digested crowns and mantles (90 % of the squid fresh remains, n = 28). Two species of ommastrephids equally dominated the squid diet, Martialia hyadesi (only found once in Kerguelen waters) and a Todarodes species, probably T. angolensis, previously unknown in the area. The concomitant satellite tracking of 16 adult birds over a total of 35 foraging trips identified their main feeding areas as the inner shelf break to the NE and over a bank to the SE of Kerguelen Island. Taken together, albatross dietary and foraging data indicate that juveniles of M. hyadesi and Todarodes sp, concentrate over the upper shelf slope to the east of Kerguelen Island, some of them occurring in the top 5 m of the water column where they are caught by the albatrosses.

Description: Many studies have demonstrated relationships between seabird prey harvests and fishenes catches. These correlations have for the most part been found at scales from 10s to 100s of kilometers within foraging ranges around seabird breeding colonies. In the present study, we investigated associations between the prey harvests of northern gannets Sula bassana at a large breeding colony off the northeast coast of Newfoundland and the catches of the inshore Newfoundland fishery at different spatial scales and time intervals. Significant correlations occurred between the seabirds' and the humans' catches of mackerel Scomber scombrus and short-finned squid Illex illecebrosus from 1977 through 1992. The relationships for squid were stronger over larger geographic areas than were those for mackerel. The associations for both squid and mackerel reflected abundance/availability around the colony, at a larger scale near the gannets' maximum foraging range (e.g. -200 km), and for the entire Newfoundland region (1000s of kilometers). These correlations were significant at August vs August and August vs annual time intervals. The gannets' landings of squid were also associated with fishery-independent, research survey indices of squid abundance over thousands of kilometers. The robustness of these relationships indicates that levels of pelagic prey harvest by seabirds can provide reliable indices of prey abundance within and outside reproductive seasons and foraging ranges around breeding colonies. Similar relationships are predicted between seabird and human fisheries that are directed at migratory 'warm-water' pelagic prey that move into cold and high latitude oceanographic regions.

Description: The diet of emperor penguins Aptenodytes forsteri was studied during late austral summer at Drescher Inlet, eastern Weddell Sea, Antarctica. Antarctic krill Euphausia superba was a major component of the food, accounting for 75% of all prey items. Emperor penguins appear to feed on krill during shallow dives under the fast sea ice. Fish, mainly nototheniids, accounted for less than 20% by number of all prey. An evaluation of the main prey types in terms of mass indicated, however, that fish represented up to 75% approximately of prey mass. Feeding experiments were performed on captive penguins and showed that squid beaks can accumulate for up to 3 weeks within the stomach without any clear signs of erosion. The lack of cephalopod soft parts in the samples makes it likely that all squid beaks were derived from animals captured some time previously. Squid seems to be a very minor dietary component of emperor penguins at the Drescher Inlet.

Description: This communication presents the first records of mated female Loligo gahi in Falkland Island waters. In October 1993 fully mature mated female L. gahi were identified in samples taken from the commercial fishery in waters east of Lively Island, East Falkland, at depths of 145–174 m. Spermatophores were found in both the mantle cavity and buccal sites of deposition. These records, combined with past records of spent females, suggest spawning periods in late October/early November and April/May. These concur with two of the three periods of spawning suggested from previous studies of juvenile and adult L. gahi.

Description: Age, growth and maturation of Loligo vulgaris were studied by examination of growth increments within statoliths of 294 specimens (mantle length, ML, ranging from 31 to 498 mm) caught on the west Saharan shelf between 1985 and 1988. Maximum age was 335 d (290 mm ML) for females, and 396 d (498 mm ML) for males. Growth rates varied considerably among individuals with a greater range in males. Sexual dimorphism in length was apparent after about 210 d. Males and females diverged considerably in weight, with males reaching a greater weight after about 180 d. Growth in length between 124 and 396 d was best described by a power function, while growth in weight was best described by the Gompertz function. Males started maturing at 180–210 d and mature males ranged in age between 250 and 396 d; while females started maturing at 240–270 d and mature females ranged between 285 and 335 d. Loligo vulgaris hatched throughout the year with two distinct peaks; in winter (December - early March) and summer (June-July). The life cycle of L. vulgaris populations on the west Saharan shelf lasts ~1 y, with large males (〉450 mm ML) living slightly longer.

Description: Fourteen enzymes involved in digestion (esterases, glycosidases and peptidases) were localized by histochemical methods in planktonic paralarvae belonging to four families of cephalopods: Octopodidae, Bolitaenidae (Octopods), Ommastrephidae and Enoploteuthidae (Oegopsid squids). The high protease activity and very low or histochemically undetectable amylasic activity indicate a carnivorous diet suggesting that the diet of paralarvae resembles that of adults. The digestive gland displays the highest enzyme activities which agrees with the key role of the gland in the digestive processes of cephalopods. In particular, the gland appears to be the main source of the proteolytic enzymes found in the posterior digestive tract. The high acid phosphatase activity, DAP II and acetyl-glycosaminidase activities, typically lysosomal, point to intracellular digestive processes in the gland. The posterior salivary glands are as well developed in squids as in octopods and they display several enzyme activities, most notably a high proteolytic activity. This could indicate that the salivary glands would be more involved in the digestive processes in paralarval squids than in adults where they are mostly poison glands. In all of the specimens studied, the whole digestive system appears to be already developed and able to digest prey. The high level of alkaline phosphatase activity of the skin suggests active exchanges with the external medium. It seems possible therefore that nutrients could be absorbed through the skin and provide a part of the energy necessary to the young cephalopods.

Description: Samples of the squid Loligo forbesi Steenstrup 1856 were obtained from commercial catches and research cruises in the Irish and Celtic Seas from August 1991 until October 1993. Age and growth of L. forbesi were estimated from putative daily statolith growth increment counts and from length-frequency data. Indirect evidence of the daily deposition of growth increments was obtained by counting increments on statoliths from immature female squid from successive monthly modes, during a four-month period when length-frequency growth estimates were high. Female growth estimates from length-frequency analysis (15–30 mm per month) were slightly lower than statolith-based estimates (30 mm per month). Statolith data indicated that both sexes had a life-span of approximately one year and that males grew faster and attained a larger size than females. In both sexes growth was found to be logarithmic over the size range sampled (28–505 mm mantle length). Mean estimated age of mature males and females was 317 and 312 days respectively, with the minimum age at maturity found to be 236 and 241 days. Back-calculations of hatching dates showed an extended spawning season from November to May. Squid hatched in the spring grew faster than those hatched in the autumn and winter. In post-recruit L. forbesi, growth of head, mantle and viscera were approximately isometric with body mass. The digestive gland showed slight positive allometry, whilst reproductive organs showed strong positive allometry.

Description: The reproductive strategies of male and female Loligo forbesi Steenstrup, 1856 were investigated from samples obtained from commercial catches and research cruises in Irish waters. In females maturity increased with size, but in males two modes in the size at maturity were identified, with approximately 40% mature at small size (180–200 mm mantle length), and the remainder mature at 〉250 mm mantle length. The difference in estimated age of the two modes of mature males was small, so size differences were probably due to different growth rates. Growth and maturation proceeded together in both sexes over much of the life-cycle. The effect of maturation on relative growth of somatic tissues was examined using analysis of covariance and multivariate regressions. In males there was a significant decline in total mass, and in mass of mantle, head and viscera, relative to mantle length with maturation. In females total mass was not significantly affected by maturation, but relative masses of head, mantle and viscera declined with maturation, indicating that energy was diverted from somatic growth to gonad production. Potential fecundity estimates were obtained by counting eggs and ova in the oviduct and ovary of mature females and were in the range 2500 to 10,500 (mean 5800). Fecundity was positively related to mantle length. The ovaries of mature females contained a range of egg sizes and developmental stages, indicating that spawning probably occurs intermittently.

Description: Late Permian reefs of the Capitan complex, west Texas; the Magnesian Limestone, England; Chuenmuping reef, south China; and elsewhere contain anomalously large volumes of aragonite and calcite marine cements and sea- floor crusts, as well as abundant microbial precipitates. These components strongly influenced reef growth and may have been responsible for the construction of rigid, open reefal frames in which bryozoans and sponges be- came encrusted and structurally reinforced. In some cases, such as the upper biostrome of the Magnesian Limestone, precipitated microbialites and inorganic crusts were the primary constituents of the reef core. These microbial and inorganic reefs do not have modern marine counter- parts; on the contrary, their textures and genesis are best understood through comparison with the older rock rec- ord, particularly that of the early Precambrian. Early Precambrian reefal facies are interpreted to have formed in a stratified ocean with anoxic deep waters en- riched in carbonate alkalinity. Upwelling mixed deep and surface waters, resulting in massive seafloor precipitation of aragonite and calcite. During Mesoproterozoic and ear- ly Neoproterozoic time, the ocean became more fully ox- idized, and seafloor carbonate precipitation was signifi- cantly reduced. However, during the late Neoproterozoic, sizeable volumes of deep ocean water once again became anoxic for protracted intervals; the distinctive "cap car- bonates" found above Neoproterozoic tillites attest to re- newed upwelling of anoxic bottom water enriched in car- bonate alkalinity and 12C. Anomalous late Permian sea- floor precipitates are interpreted as the product, at least in part, of similar processes. Massive carbonate precipi- tation was favored by: 1) reduced shelf space for carbonate precipitation, 2) increased flux of Ca to the oceans during increased continental erosion, 3) deep basinal anoxia that generated upwelling waters with elevated alkalinities, and 4) further evolution of ocean water in the restricted Del- aware, Zechstein, and other basins. Temporal coincidence of these processes resulted in surface seawater that was greatly supersaturated by Phanerozoic standards and whose only precedents occurred in Precambrian oceans.

Description: Fifteen species and morphotypes of planktonic foraminifera from three core-tops in the tropical Atlantic were chosen for 6' 80 and 613C analyses. For each species several size fractions were analyzed. 6' 80 values are used to predict calcification temperature. Since temperature varies linearly with 6' 3C of IC02 of sea water due to mixing of upwelling waters with surface waters, it can be used to predict the 6'3C of IC02 of sea water. Measured d13C values are compared lo the predicted 613C of IC02 of sea water in order to determine the offsets of each size fraction of each species from the sea water values. Spinose species, and Neogloboquadri11a dutertrei have d13C offsets that vary as a function of size due to changing biological or kinetic fractionation effects as the foraminifera increases in size. For species measured from more than one site, the size-dependent fractionation is consistent between the sites which are located in regions with extremely different hydrographic conditions. Little to no size-dependent fractionation is found in Globorotalia menardii, G. tumida, G. injlata, G. crassaformis, G. truncatulinoides, and Pulleniatina obliquiloculata. Temperature dependenl kinetic fractionation of oxygen and carbon is found in G. menardii, G. crassaformis, G. trwrcatulinoides, and possibly G. injlata. No temperature dependent fractionation is apparent in G. tumida and P. obliquiloculata. lnter-core differences in the 613C offsets from sea water composition for each species may be due to inadequate constraints on sea water chemistry.

Description: The eukaryotic green alga Dunaliella tertiolecta acclimates to decreased growth irradiance by increasing cellular levels of light-harvesting chlorophyll protein complex apoproteins associated with photosystem II (LHCIIs), whereas increased growth irradiance elicits the opposite response. Nuclear run-on transcription assays and measurements of cab mRNA stability established that light intensity-dependent changes in LHCII are controlled at the level of transcription. cab gene transcription in high-intensity light was partially enhanced by reducing plastoquinone with 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU), whereas it was repressed in low-intensity light by partially inhibiting the oxidation of plastoquinol with 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB). Uncouplers of photosynthetic electron transport and inhibition of water splitting had no effect on LHCII levels. These results strongly implicate the redox state of the plastoquinone pool in the chloroplast as a photon-sensing system that is coupled to the light-intensity regulation of nuclear-encoded cab gene transcription. The accumulation of cellular chlorophyll at low-intensity light can be blocked with cytoplasmically directed phosphatase inhibitors, such as okadaic acid, microcystin L-R, and tautomycin. Gel mobility-shift assays revealed that cells grown in high-intensity light contained proteins that bind to the promoter region of a cab gene carrying sequences homologous to higher plant light-responsive elements. On the basis of these experimental results, we propose a model for a light intensity signaling system where cab gene expression is reversibly repressed by a phosphorylated factor coupled to the redox status of plastoquinone through a chloroplast protein kinase.

Description: The chemical composition of sediments from the Reykjanes Ridge is controlled by allochthonous and autochthonous processes. The surface sediments are characterized by relatively high contents of calciumoxide and strontium. Calcium and strontium dominate in the carbonate phase due to the high content of biogenic carbonate. A high percentage of iron and manganese are bound to oxides and hydroxides. An indication of hydrothermal activity was not observed. A considerable portion of adsorbed barium is transported in clay minerals. The higher amounts of aluminium in glacial sequences indicate an enhanced input of terrigenous material; the increase of stable bonding elemen~s points toward the large influence of detrital minerals. The distinct differences in the bonding characteristics of elements in these marine sediments in comparison to fluvial and coastal - deposits could be due to the different environmental conditions.

Description: Deep-sea sediments deposited at or near an actively spreading mid-ocean ridge experience a distinctly different thermal history than sediments deposited in other marine geotectonic settings. For sediments of a given age the impact of high heat flow decreases with increasing distance from the ridge. This simple relation is superimposed in the active spreading ridge along the margin of Southern Chile—the Chile Triple Junction—by the process of sediment accretion. Both processes, heat flow and lateral thrusting, strongly modify the mechanical behavior of sediment accreted. The original intent was to study the mechanical state of accreted sediment recovered during Ocean Drilling Program (ODP) Leg 141, both unaltered and altered diagenetically by hydrothermal fluids, to differentiate the effects of thermal and mechanical diagenesis. The research program included high-pressure oedometer as well as triaxial testing to quantify the relative importance of both diagenetic processes for shear strength and consolidation behavior. Unfortunately, whole-round core samples available from Leg 141 appeared to be inadequately preserved and only a limited number of specimens could be used for mechanical testing. Therefore, most of the pre-cruise goals could not be attained. This paper reports the results of oedometer as well triaxial tests obtained from a restricted testing program.

Description: Three groups of siliceous flagellates are discussed from Sites 860 and 861 in the southeastern South Pacific Ocean off southern Chile. Three silicoflagellate zones and two ebridian/actiniscidian zones are recognized in upper Pliocene to Quaternary sediments. Repeated occurrences of Dictyocha messanensis messanensis demonstrate that the cool subpolar water masses of the Peru Current were mixed with or replaced by warm transitional water masses of the central South Pacific several times during late Pliocene to middle Pleistocene times. Continuous occurrences of Dictyocha messanensis aculeata in Zone NN21 sediments reflect an enhanced influence of transitional surface-water also during late Pleistocene and Holocene times. These Pliocene and Quaternary warming episodes may have been caused by strong El Nino activities, which resulted in a southward shift of the transitional water belt and an expansion of warmer surface-water over the study area.

Description: A method to derive salinity data from RAFOS float temperature and pressure measurements is described. It is based on evaluating the float's in situ density from its mechanical properties and in situ pressure and temperature data. The salinity of the surrounding water may then be determined, assuming that the float has reached equilibrium with its environment. This method, in comparison with the possible use of floatborne salinity cells, has the advantage of being both cost and energy neutral and highly stable in the long term. The effect on the estimated salinity of various parameters used in the determination of the float's in situ density is discussed. Results of seven RAFOS Boats deployed in the Brazil Basin are compared with corresponding CTD data to estimate the magnitude of these errors. At present, an accuracy of 0.3 psu is achieved. The accuracy may be improved to 0.02 psu by referring the float's calculated density to a reference density established by a CTD cast at the time of launch. Results from five floats deployed in the heterogeneous water masses of the Iberian Basin are compared with the corresponding CM casts to demonstrate the variability and interpretation of p-T-S float datasets from different areas.

Description: Logs collected while drilling measured density in situ, through the accretionary prism and decollement zone of the northern Barbados Ridge. Consolidation tests relate void ratio (derived from density) to effective stress and predict a fluid pressure profile, assuming that the upper 100 m of the prism is at a hydrostatic pressure gradient. The calculated fluid pressure curve rises to 〉90% of lithostatic below thrusts in the prism, presumably due to the increase in overburden and lateral tectonic loading. Thin (0.5–2.0 m) intervals of anomalously low density and resistivity in the logs through the basal decollement zone suggest dilation and perhaps hydrofracturing. A peak in hydraulic head in the upper half of the decollement zone requires lateral influx of fluid, a conclusion consistent with previous geochemical studies. Although the calculated fluid-pressure profile is model dependent, its inherent character ties to major structural features.

Description: Dinoflagellate cysts and other organic-walled microfossils have been studied in recent surface sediments from the entire Norwegian-Greenland Sea. More than 30 taxa have been recognized, of which only few show a distinct distribution pattern, and allow description of four assemblages. The occurrence of most taxa is related to the relatively warmer waters of the Norwegian Sea. Algidaspaeridium? minutum s.1., Brigantedinium simplex and Impagidinium? pallidum are the only species showing a preference for colder water masses. Two species, I.? pallidum and Nematosphaeropsis labyrinthus are mainly restricted to the oceanic environment, whereas the other species have also been reported from neritic environments in previous studies. Due to the limited knowledge of the ecological and sedimentological factors influencing the occurrence of dinoflagellate cysts in oceanic environments, their distribution in recent sediments can be only related to surface water masses in a broad sense. Although the distribution of assemblages correlates with specific surface water masses, comparison with assemblages recovered from sediment traps deployed basinwide in the Norwegian-Greenland Sea (Dale and Dale, 1992) revealed some major discrepancies in species composition and percentage abundances. The differences cannot be explained with certainty at the moment, although there is some evidence that transport of dinoflagellate cysts and other fossilizable microplankton in water masses by currents, in sea-ice and sediments may modify the assemblages found in recent oceanic surface sediments from the Norwegian-Greenland Sea.

Description: The distributions and transports of deepwater masses at the western boundary in the tropical Atlantic off Brazil have been studied on three surveys along 35 degrees W and 5 degrees S and one at 10 degrees S. Transports are obtained from direct measurements of the velocity fields (Pegasus profiling system and lowered acoustic Doppler current profiler) and from geostrophic computations. Using chlorofluoromethane (CFM) and hydrographic distributions, four water masses could be identified forming the North Atlantic Deep Water (NADW) system. Two of these have a high CFM content, the ''shallow upper NADW'' (SUNADW) and the ''overflow lower NADW'' (OLNADW). These exhibit the highest velocity signals at 35 degrees W, where distinct flow cores seem to exist; most of the southeastward flow of the SUNADW (centered around 1600 m) occurs 320 km offshore between 3 degrees 09'S and 1 degrees 50'S (9.7 +/- 3.3 Sv); farther north in that section, a highly variable reversing flow is found in a second velocity maximum. The transport of OLNADW (centered around 3800 m) of 4.6 +/- 2.6 Sv is guided by the Parnaiba Ridge at 1 degrees 45'S, 35 degrees W. The water masses located between the two CFM maxima, the Labrador Sea Water (LSW) and the LNADW old water mass (LNADW-old), did not show any persistent flow features, however, a rather constant transport of 11.1 +/- 2.6 Sv was observed for these two layers. The total southeastward flow of the NADW at 35 degrees W showed a transport of 26.8 +/- 7.0 Sv, if one neglects the reversing SUNADW north of 1 degrees 50'S. At 5 degrees S the flow of all deepwater masses shows vertically aligned cores; the main southward transport occurred near the coast (19.5 +/- 5.3 Sv). The boundary current is limited offshore by a flow reversal, present in all three surveys, but located at different longitudes. At 10 degrees S a southward transport of 4.7 Sv was observed in November 1992. However, the section extended only to 32 degrees 30'W, so that probably a significant part of the flow has been missed. An important result is the large transport variability between single cruises as well as variability of the spatial distribution of the flow at 35 degrees W, which could lead to large uncertainties in the interpretation of single cruise observations. Despite these uncertainties we suggest a circulation pattern of the various deepwater masses near the equator by combining our mean transport estimates with other observations.

Description: The flow field in the area of what was thought to be the source region of the North Brazil Current (NBC) off the northeast coast of Brazil between 5 degrees 30'S and 10 degrees S was investigated in austral spring during November 1992 and compared with observations in October 1990. The data were taken with several different instruments, including vessel-mounted ADCP, lowered-ADCP, Pegasus, CTD and XBTs. The flow was found off the coast at 5 degrees 30'S as well as at 10 degrees S as an undercurrent, the North Brazil Undercurrent (NBUC). The NBUC shows a subsurface core at about 200 m depth with velocities of up to 90.0 cm s(-1), resulting in large northward transports of more than 22 Sv in the upper 1000 m. The transport is about the same at 5 degrees 30'S and 10 degrees S, hence no net inflow from the east is required to feed the NBUC. The climatological Ekman transport is to the south between 5 degrees 30'S and 10 degrees S, and in consequence the northward flow near the surface was reduced and might be one reason for the existence of the undercurrent. The flow near the coast was to the north at 10 degrees S, therefore the Brazil Current had to start as a coastal current south of 10 degrees S. For the zonal sections at 5 degrees 30'S and 10 degrees S the geostrophic computations relative to the density surface sigma(1) = 32.15 kg m(-3) (about 1150 m depth) resulted in transports comparable to those obtained from direct measurements. The results further show that the choice of a correct level of no motion can be supported by the direct observations. A shallower reference based on water mass boundaries alone would reduce the NBUC transport to almost zero. Computations with data from the historical data base for austral fall resulted in a weaker NBUC of less than 20 Sv near 10 degrees S, indicating a possible seasonal signal in the NBUC with a stronger NBUC in austral spring.

Description: During March 1994 a survey of the western boundary of the tropical Atlantic, between 10 degrees N and 10 degrees S, was carried out by conductivity-temperature-depth and current profiling using shipboard and lowered acoustic Doppler current profilers. In the near-surface layer, above sigma. = 24.5, the inflow into the boundary regime came dominantly from low latitudes; out of the 14 Sv that crossed the equator in the upper part of the North Brazil Current (NBC), only 2 Sv originated from south of 5 degrees S, while 12 Sv came in from the east at 1 degrees-5 degrees S with the South Equatorial Current (SEC). After crossing the equator near 44 degrees W, only a minor fraction of the near-surface NBC retroflected eastward, while a net through flow of about 12 Sv above sigma. = 24.5 continued northwestward along the boundary, By contrast, in the isopycnal range sigma. = 24.5-26.8 encompassing the Equatorial Undercurrent (EUC), the source waters of the equatorial circulation were dominantly of higher-latitude South Atlantic origin. While only 3 Sv of eastern equatorial water entered the region through the SEC at 3 degrees-5 degrees S, there was an inflow of 10 Sv of South Atlantic water in the North Brazil Undercurrent (NBUC) along the South American coast that originated south of 10 degrees S, The transport of 14 Sv arriving at the equator along the boundary in the undercurrent layer was almost entirely retroflected into the EUC with only marginal northern water additions along its path to 35 degrees W. The off-equatorial undercurrents in the upper thermocline, the South and North Equatorial Undercurrents carried only small transports across 35 degrees W, of 5 Sv and 3 Sv, respectively, dominantly supplied out of SEC recirculation rather than out of the boundary current. Still deeper, three zonal undercurrents were observed: the westward-flowing Equatorial Intermediate Current (EIC) in the depth range 200-900 m below the EUC, and two off-equatorial eastward undercurrents, the Northern and Southern Intermediate Countercurrents (NICC, SICC) at 400-1000 m and 1 degrees-3 degrees latitude. In the lower part of the NBUC there was an Antarctic Intermediate Water (AAIW) inflow along the coast of 6 Sv, and there was a clear connection at the AAIW level to the SICC by low salinities and high oxygens and a weaker suggestion also that some supply of the NICC might be through AAIW out of the deep NBUC.

Description: In this study we analyze two groups of Mediterranean salt lenses: ''mid-life'' lenses, typically 1-2 years old, observed in the Canary Basin, and younger Meddies from the Iberian Basin. In contrast to turbulent features, vortex lenses have a clear coherent structure in the temperature and salinity fields. This physical property supports the hypothesis that a mathematical description with only a few degrees of freedom may exist. We use nonlinear transformation of variables to find a unique function describing vertical profiles at different locations inside the lens. When this function is found, its existence is considered as ''self-similarity'' of the lens structure. We also found a common function that describes each group of Meddy, Canary and Iberian, and noted a remarkable difference between the groups. A possible reason for this result might lie in the difference in lens age. Iberian lenses are in a more juvenile state and may go through adjustment transformations before turning into more stable mid-life vortices. The developed parameterization is used to calculate radii and integral heat and salt contents of Meddles.

Description: Das Klima der geologischen vorzeit unterlag einem ständigen Wandel. So war es in der Kreidezeit vor etwa 100 Mio. Jahren, als die Dinosaurier noch lebten, deutlich wärmer als heute, und tropische Pflanzen besiedelten auch die höheren Breiten unserer Erde. Legt man hingegen nur die Klimaschwankungen der letzten 3 Mio. Jahre zugrunde, in denen Eiszeiten und Warmzeiten in zyklischen zeiträumen von 20000 bis 100000 Jahren miteinander wechselten, so erfreuen wir uns heute eines Klimas, das optimaler kaum sein könnte. Noch vor 22000 bedeckten nämlich mächtige Eismassen große Teile der Nordhalbkugel, und die Wüstengebiete der Subtropen erreichten ihre größte Ausdehnung. Aber auch während der letzten 1000 Jahre gab es wiederholt kurzfristige Klimaschwankungen, wie z. B. die der "Kleinen Eiszeit" von 1450 bis 1850 n. Chr. Strenge Winter und kältere Sommer prägten damals das Klima in Europa und Nordamerika.

Description: The Southern Hemisphere Subtropical Front (STF) is a narrow zone of transition between upper-level subtropical waters to the north and subantarctic waters to the south. It is found near 40 degrees S across the South Atlantic and South Indian Oceans and is associated with an eastward geostrophic current band, The current band in each basin is found at or just north of the surface front except near the eastern boundaries where most of the subtropical waters turn north into the eastern limbs of the subtropical gyres. The bands associated with the STF are thus distinct features separated from the strong zonal flows of the Antarctic Circumpolar Current farther south. The authors have referred to the current bands in the two respective oceans as the South Atlantic Current and the South Indian Ocean Current. In this paper the authors use the historical database from the South Pacific Ocean to investigate the geostrophic flow associated with the STF there. The STF extends across the southern Tasman Sea from south of Tasmania to southern New Zealand, and a weak eastward flow appears to be associated with it. The transport amounts to only about 3 Sv (1Sv = 10(6) m(3) s(-1)), little of which passes south of New Zealand. Mixing within the eddy-rich Tasman Sea may account for this weakness, while also setting up another more significant front in the northern Tasman Sea, the Tasman Front. It branches off from the East Australian Current toward the north of New Zealand, along which moves a flow of about 14 Sv. After passing north of New Zealand, a portion of this current flows east to contribute to a current band near 30 degrees S, while another portion turns south as the East Auckland Current and meets with subantarctic waters near Chatham Rise (44 degrees S), thus reestablishing the STF. An enhanced eastward current band is associated with the front there, one that extends across the remainder of the South Pacific and is referred to as the South Pacific Current. In comparison with its counterparts in the other basins, which typically begin by carrying 30 Sv (Atlantic) to 60 Sv (Indian) in the upper 1000 m in their western portions before weakening to 10-15 Sv in the east, the South Pacific Current is weak. Near Chatham Rise, it starts with a transport of approximately 5 Sv, and it remains near this strength as it shifts gradually north across the basin toward South America. The current appears to split into two smaller bands in the region of 115 degrees-85 degrees W, while near 28 degrees 5, 83 degrees W it begins to turn more strongly north and becomes shallower and weaker. Potential vorticity distributions indicate that this current acts as an impediment toward the northward spreading of Antarctic Intermediate Water, But why the South Pacific Current east of New Zealand should be so much weaker than its counterparts in the other basins is not particularly clear. It may be due to the presence of New Zealand and other topographic barriers to deep now east of Australia, to the axis of the subtropical gyre in the South Pacific shifting more rapidly southward with depth than those elsewhere, thus causing greater reductions in the underlying zonal velocities, and to strong poleward eddy heat and salt fluxes in the other two basins leading to smaller cross-STF gradients in the Pacific.

Description: While the aggregation and mass settlement of diatoms at the termination of blooms results in significant export of carbon from the surface ocean, the mechanisms of bloom aggregation have been poorly understood. The aggregation of a multispecies diatom bloom was investigated under controlled conditions in a 1200 liter, nutrient-enriched, laboratory mesocosm in order to elucidate the parameters sufficient to accurately predict bloom aggregation. A diverse bloom of diatoms dominated by several species of Chaetoceros and Thalassiosira progressed through a classic pattern of exponential, stationary, and senescent phases in the mesocosm. Aggregates larger than 0.5 mm became detectable on the eighth day after inoculation, and aggregates 〉1 mm increased exponentially from Day 10 onward producing the appearance of a mass aggregation event late on Day 10. The bloom aggregated sequentially with Thalassiosira dominating early aggregates and Chaetoceros dominating later ones. Chaetoceros resting spores formed only in aggregates. Aggregation was not linked to nutrient depletion or to the physiological state of the cells since the onset of aggregation and the mass aggregation event occurred 1 to 3 days prior to nutrient depletion and while carbon:nitrogen ratios of cells were still very low and growth rates high. Moreover, visible aggregates did not form in the mesocosm until cell abundances were considerably higher than abundances observed to aggregate in nature, suggesting that aggregation was not strongly linked to phytoplankton cell concentration. Complementary studies in this volume clarify the role of non-phytoplankton particles in aggregation of the mesocosm bloom. The mesocosm approach proved highly effective in producing an aggregating diatom bloom under controlled conditions.

Description: This note describes a method for the determination of the age of individual water mass contributions in a mixture of water masses. The method is based on a combination of Optimum Multi parameter analysis and CFC analysis. Synthetic data designed to mirror the situation in the permanent thermocline of the eastern Indian Ocean are used to demonstrate the method. The feasibility of applications to oceanic data is discussed.

Description: The pelagic nekton community was sampled with the RMT 25 opening/closing net and a neuston net at two stations in the Scotia Sea south of the Antarctic Polar Front in the open ocean (Station 1) and on the South Georgia northwestern slope (Station 2). Downward oblique tows were made with the RMT 25 through discrete 200 m layers to 1000 m in daylight and darkness. A total of 119 cephalopods representing nine species were removed from the samples, and mantle and arm lengths were measured to the nearest 0.1 mm. The most abundant species at each station was an undescribed Brachioteuthis sp. (B. ?picta). Galiteuthis glacialis and Alluroteuthis antarcticus were caught at both stations. Histioteuthis eltaninae, Bathyteuthis abyssicola and Psychroteuthis glacialis were caught at Station 1. Mastigoteuthis psychrophila and a Chiroteuthis sp. were caught at Station 2. B. ?picta was present throughout the water column to 1000 m at both stations, with little evidence of ontogenetic descent. There was evidence for ontogenetic descent in G. glacialis. This species was absent from the Antarctic Surface Water (ASW) at Station 1, where it was concentrated in the Circumpolar Deep Water (CDW). At Station 2 it was present throughout the water column to 1000 m. The other species were all caught in the core of the CDW (〉400 m). In juvenile B. ?picta, G. glacialis and A. antarcticus, growth of the brachial crown is positively allometric with respect to mantle length. Recent data on biomass spectra in high-latitude pelagic systems show that they are characterised by the presence of peaks of biomass separated by biomass minima. Positive allometric growth in the brachial crown of these antarctic oceanic squid is suggested to have evolved as an adaptation to the peaked, or domed, structure of the pelagic biomass spectrum which must be spanned by these predators as their optimum prey size increases with growth. Interspecific differences in the allometry of tentacle growth are probably related to differences in strategies for stalking and capture of prey.

Description: We reconstructed late Quaternary deep (3000–4100 m) and intermediate depth (1000–2500 m) paleoceanographic history of the Eurasian Basin, Arctic Ocean from ostracode assemblages in cores from the Lomonosov Ridge, Gakkel Ridge, Yermak Plateau, Morris Jesup Rise, and Amundsen and Makarov Basins obtained during the 1991 Polarstern cruise. Modern assemblages on ridges and plateaus between 1000 and 1500 m are characterized by abundant, relatively species-rich benthic ostracode assemblages, in part, reflecting the influence of high organic productivity and inflowing Atlantic water. In contrast, deep Arctic Eurasian basin assemblages have low abundance and low diversity and are dominated by Krithe and Cytheropteron reflecting faunal exchange with the Greenland Sea via the Fram Strait. Major faunal changes occurred in the Arctic during the last glacial/interglacial transition and the Holocene. Low-abundance, low-diversity assemblages from the Lomonosov and Gakkel Ridges in the Eurasian Basin from the last glacial period have modern analogs in cold, low-salinity, low-nutrient Greenland Sea deep water; glacial assemblages from the deep Nansen and Amundsen Basins have modern analogs in the deep Canada Basin. During Termination 1 at intermediate depths, diversity and abundance increased coincident with increased biogenic sediment, reflecting increased organic productivity, reduced sea-ice, and enhanced inflowing North Atlantic water. During deglaciation deep Nansen Basin assemblages were similar to those living today in the deep Greenland Sea, perhaps reflecting deepwater exchange via the Fram Strait. In the central Arctic, early Holocene faunas indicate weaker North Atlantic water inflow at middepths immediately following Termination 1, about 8500–7000 year B.P., followed by a period of strong Canada Basin water overflow across the Lomonosov Ridge into the Morris Jesup Rise area and central Arctic Ocean. Modern perennial sea-ice cover evolved over the last 4000–5000 years. Late Quaternary faunal changes reflect benthic habitat changes most likely caused by changes in the import of cold, deepwater of Greenland Sea origin and warmer and middepth Atlantic water to the Eurasian Basin through the Fram Strait, and export of Arctic Ocean deepwater.

Description: Three methods of estimating H20 contents of geologic glasses are compared: (1) ion microprobe analysis (secondary ion mass spectrometry), (2) Fourier-transform infrared spectroscopy (FTIR), and (3) electron microprobe analysis using the Na decay-curve method. Each analytical method has its own advantages under certain conditions, depending on the relative importance of analytical accuracy, precision, sensitivity, spatial resolution,and convenience, and each is capable of providing reasonably accurate estimates of the H20, or total volatile, content of geologic glasses. The accuracy of ion microprobe analyses depends critically on the availability of well-characterized hydrous standard glasses. Precision is often better than 0,2 wt% (10). The method provides good spatial resolution (-15 #m) and the capability to determine simultaneously the abundance of other volatile species of interest (e.g., F, B). FTIR spectroscopy provides excellent analytical sensitivity (-10 ppm), accuracy and precision «0.1 wt%), and the capability to determine the abundance of H20 and C02 species (H20, OH-, C02' eOj-) in analyzed glasses, although the spatial resolution (〉 25-35 #m) is not as good as that of the ion microprobe. The main advantages of the estimation of H20 contents of hydrous glasses using the electron microprobe are excellent spatial resolution (- 10 #m) and analytical convenience. The disadvantages are that accuracy and precision (〉0.5 wt%) are not as good as those associated with the other methods, but, for certain applications, these uncertainties may be acceptable for the estimation of H20 contents of H20-rich (〉 1 wt%) samples.

Description: The history of the Late Weichselian northwestern Barents Shelf, including western Svalbard, has been investigated by provenance/sedimentologist studies of five cores from the continental shelf and slope west of Svalbard. The chronostratigraphy of the cores is based on AMS 14C dates and oxygen isotope analyses. Interpretations of the cores suggest that the ice sheets of western Svalbard and northwestern Barents Sea experienced advances and retreats in two steps. The first significant ice advance beyond the present coastline occurred ca. 22,000 14C yr B.P. and was followed by an ice advance to the shelf edge ca. 18,000 14C yr B.P. Ice recession from the outer shelf and the southwestern Barents Sea began 14,800 14C yr B.P. and was followed by a second ice recession between 13,000 and 12,000 14 C yr B.P. during which ice withdrew from the inner shelf. A minor readvance of the ice sheet on the shelf west of Svalbard occurred close to 12,400 14C yr B.P. The first deglaciation event was associated with release of icebergs containing ice-rafted detritus, while the later episode also included significant amounts of meltwater and fine-grained sediment.

Description: Sediment cores of 20 cm diameter contaning the natural benthic fauna were subjected to low oxygen conditions in a laboratory microcosm system. After several days of oxic conditions ('oxic stage') the oxygen content of the water was reduced to 25% saturation for 15 d ('hypoxic stage'), followed by a 'reoxygenation stage'. Effective solute transport rates were calculated using measurements with the conservative tracer ion bromide. Profiles of oxygen and ΣCO2 were measured and molecular diffusive as well as effective fluxes, account mg for effective solute exchange, were calculated. The overall response of the benthic community was to compensate for low oxygen content of the overlying water by increased pumping activity. On average, effective diffusion coefficients (Den} were 3 times higher in hypoxia than under oxic conditions. D eff reached 1.5 x 10^-4 cm2 s^-1, a value 30 times that of molecular diffusion. During hypoxia we observed low molecular diffusive O2 flux, higher effective O2 flux, as well as an increase in ΣCO2 within the sediment. We interpret this as a shift of transport away from diffusion within the bulk sediment interstices (oxic conditions) to the advective transport pathways along burrows during hypoxia. This facilitates fast transport of oxygen and bromide along burrows and contrasts with the slower transport of CO2 from the interstices governed by molecular diffusion. In this transient situation calulations based on gradients result in an unrealistic molar ratio of fluxes(CO2/O2)as high as 11.