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We critically evaluate the applicability of Ca-isotope ratios in planktonic foraminifers as proxy for past sea surface temperatures (SST) and isotope composition of paleo-seawater (δ44Casw) reconstructions. Previous studies have shown discrepancies regarding the temperature sensitivity of Ca isotope fractionation in foraminifers of more than one order of magnitude. We present new data from the planktonic foraminifer species Orbulina universa, Globigerinoides sacculifer and Neogloboquadrina pachyderma (sinistral) from culture experiments, multinet deployments and coretop samples. Specimens of G. sacculifer cultured at low salinities (33–34.5) show predominantly no major temperature dependent Ca isotope fractionation, in contrast to previous individuals cultured at higher salinities of 34.5–36. The new data of O. universa are consistent with previously published results, revealing a small but significant temperature sensitivity. Calcium isotope fractionation in tests of N. pachyderma shows a significant variation with temperature, which is not uniform over the total investigated temperature range (−1.6 °C to +10 °C), possibly reflecting the influence of additional controlling factors besides temperature. Controlled dissolution experiments in the laboratory indicate that the Ca-isotope composition of G. sacculifer and N. pachyderma is relatively insensitive to partial dissolution of their tests. Calcium isotope ratios in the planktonic foraminifers G. sacculifer and N. pachyderma (s) reveal a complex Ca isotope fractionation behaviour, which is not yet fully understood. Additional validation studies are crucial to enhance the basic understanding of the calcium isotope systematics in planktic foraminifer shells, and the potential for applying Ca-isotope ratios as proxies for seawater temperature and the oceanic Ca budget.

Tergipes antarcticus (Gastropoda, Nudibranchia) has been reported from Antarctic sea ice twice (1903 and 2008). The extent of its distribution and life history remained unclear. We have evaluated data from several cruises, showing that T. antarcticus is widely distributed in sea ice throughout the Weddell Sea. Adults, juveniles, larvae and egg clutches of T. antarcticus were found in the ice indicating that the species reproduces within this habitat. We collected live material of T. antarcticus for a thorough description of all life stages and to investigate the developmental stages and physiological adaptations. Total developmental time from egg to veliger larvae was relatively short with 31 days (range 13–65 days) at 0°C. Liquid withdrawn from egg clutches and adult T. antarcticus showed clear signs of thermal hysteresis. This is the first report of thermal hysteresis from a sea ice metazoan. We conclude that T. antarcticus is an autochthonous species to Antarctic sea ice.

Between May 2004 and May 2005, we studied the horizontal and vertical movements of foraging Galapagos penguins Spheniscus mendiculus during their breeding season to examine space use at sea and to compare the volume of water exploited by this penguin to those of other penguin species. A total of 23 adult penguins (11 males and 12 females) brooding chicks were fitted with GPS- depth recorders at the 3 main nesting sites on south-western Isabela Island. Birds moved between 1.1 and 23.5 km (mean = 5.2 ± 4.9 km) from the nest, concentrating foraging in a strip of sea within 1.0 km of the shore. Foraging trips lasted a mean of 8.4 ± 2.0 h. Although the deepest dive was 52.1 m, birds spent, on average, 90% of their time underwater at depths less than 6 m. Both foraging ranges and dive depths were below those predicted from allometric regressions derived from other penguin species. Applying the maximum values for movement to calculate space use, the Galapagos penguin exploits a maximum volume of water of

The Laptev Sea is a high-Arctic epicontinental sea north of Siberia (Russia) that is one of the least understood regions of the world’s ocean. It is characterized by a shallow and broad shelf plateau, high influx of river water, sediments and nutrients during summer, long-lasting sea-ice cover from October to May, and the formation of a narrow flaw-lead polynya off the fast-ice edge during winter. Here, we describe results of a German–Russian research project (1993-present), presenting the distribution patterns and dynamics of its marine flora and fauna, as well as pathways and processes of coupling between sea-ice, water-column and sea-floor biota. Three ecological zones are distinguished along a combined east–west and Lena-impact gradient, differing in the composition of pelagic and benthic communities. In general, high Chl a concentrations in the sediments indicate a tight coupling between sympagic and pelagic primary production and nutrient supply to the benthos throughout the entire Laptev Sea. However, there were pronounced regional differences between the ecological zones in magnitude of primary production and trophic dynamics. Primary production during the ice-free summer was highest in the estuarine zone most strongly influenced by the Lena River (210 mg C m −2 day −1 ). The western and northeastern Laptev Sea yielded 55 and 95 mg C m −2 day −1 , respectively. Moreover, the zones differed in the partitioning of carbon flux between zooplankton and benthic food webs. In the Lena zone zooplankton carbon demand was about 31 mg C m −2 day −1 whereas in the western zone it was 21 mg C m −2 day −1 and in the eastern zone 4 mg C m −2 day −1 . Total benthic carbon demand was 32 mg C m −2 day −1 for the Lena zone, 56 mg C m −2 day −1 in the western zone and 100 mg C m −2 day −1 in the northeastern zone. A carbon budget constructed for the Laptev Sea indicates that (1) a high proportion of primary production is channelled through the benthic trophic web, bypassing the pelagic trophic web, and (2) autochthonous primary production in the northeastern and western Laptev Sea might not be sufficient to fuel both pelagic and benthic secondary production and, hence, input of allochthonous organic carbon is required to balance the overall carbon demand.

The aim of this study was to qualify the impact advection has on local populations of planktonic organisms. The study area was Kongsfjorden, an open glacial fjord on the West Coast of Spitsbergen, divided into two basins. On a cruise in May 2001 water masses with different salinity and temperature characteristics were identified from CTD data and sampled for mesozooplankton. Water velocity was measured with a ship-mounted broad band ADCP. Flux of the calanoid copepods Calanus finmarchicus and Calanus glacialis was calculated and based on this advection of zooplankton into the fjord was determined by simulation. The younger copepodite stages were concentrated in surface and subsurface waters and subject to high water velocities. Thus the advective impact on these copepodites was high. Older stages were located deeper in the water column and could maintain their position for a longer time. An eddy was observed in the outer basin and retained zooplankton in the fjord in simulations. The inner basin is likely to be more isolated from the shelf and residence time in this basin is thus probably longer. Calanus finmarchicus was most abundant in the outer basin at the periphery of the eddy and the population in May in Kongsfjorden consisted presumably mainly of individuals advected into the fjord from the surrounding shelf. Calanus glacialis was most abundant in the inner basin and local production there is assumed to exceed advection. Net inflow of zooplankton exceeded outflow during the study period. This impact of zooplankton is probably of high importance for higher trophic levels.

The Arctic sea ice is the habitat of an astonishing abundance of plant and animal life. These biocenoses have a momentous impact on the polar ecosystem

The concentration and size distribution of exopolymer particles were measured in and below pack ice in the Fram Strait area during autumn 1999. Vertical profiles of exopolymer particles were determined in young, first-year and multi-year sea ice. In addition, a variety of abiotic parameters (temperature, salinity, NO 2 , PO 4 , NO 3 , SiO 2 ) and biotic parameters (particulate organic carbon [POC] and nitrogen [PON], chlorophyll a [chl a], abundances of diatoms and bacteria) were measured. Median abundances and areas of exopolymer particles in the different ice types (3.17 x 10 6 to 4.90 x 10 6 particles 1 -1 and 4.6-6.9 cm 2 1 -1 , respectively) exceeded median concentrations in the under-ice water (0.56 x 10 6 particles 1 -1 ; 0.6 cm 2 1 -1 ) by 1 order of magnitude. Exopolymer particle concentrations in sea ice were highest in the interior of the sea ice and were significantly correlated with chl a as well as with the abundances of pennate diatoms, centric diatoms and bacteria. Our data indicate that pennate diatoms are the main producers of exopolymer particles in sea ice. The observed exopolymer particle-size spectra in both sea ice and under-ice water differed from those commonly reported for exopolymer particles in pelagic environments by a relatively large fraction of large particles. Crude estimates of integrated exopolymer particle carbon indicate that these particles can be important components in the context of food-web structure and organic carbon dynamics in the sea ice habitat. The high concentrations of exopolymer particles in the sea ice will also impact the fate of other particles during ice melt.

Physical, chemical and biological properties of sea ice and underlying brackish water (0–10 m water depth) were investigated in the Bothnian Bay and at a coastal station at the entrance of the Gulf of Finland in March 2000. Sea-ice texture was analysed and vertical profiles for δ18O, inorganic nutrient concentrations [NO3 –, NO2 –, NH4 +, PO4 3+, Si(OH)4] and chlorophyll a and pheopigment concentrations were obtained with a vertical resolution of 1–10 cm. Biomass estimates of bacteria, protists and metazoans were based on microscopical counts. Due to low ice bulk salinities, sea-ice brine volumes were small with a median value of only 3%. Ice thickness varied between 22 and 27 cm. Refrozen snow and granular ice dominated in the surface parts of the sea ice; columnar ice formed the bottom layers. The total biomass in the sea ice and under-ice water ranged from 2.7 mg C m–2 to 45.1 mg C m–2 and 36.8 mg C m–2 to 3,874.3 mg C m–2, respectively. Mean integrated ice values were dominated by pennate diatoms (33%), followed by centric diatoms (29%), autotrophic flagellates (23%), bacteria (8%) and heterotrophic flagellates (7%). The low integrated biomass of ice-associated metazoans (1%) consumed on average only 1.5% of the algal standing stock per day. The combined data suggest that abiotic factors (particularly nutrient availability as reflected by small brine volumes), rather than the heterotrophic component of the sympagic community, controlled autotrophic biomass in Baltic sea ice during March 2000.

The shipworm Teredo navalis L. is a xylophagous bivalve mollusc (Bivalvia: Teredinidae) with a long record of being very destructive to wooden ships and harbour buildings. It has been reported from numerous sites at the coasts of both the North and Baltic Seas since the eighteenth century. Here, we document for the first time the occurrence of live adult T. navalis in the harbours of Bremerhaven (Weser estuary, northern Germany). From August to December 1998, various wooden structures (fir floating fenders and pier posts, oak piles) from seven stations in different docks of two harbours (Uberseehafen, Fischereihafen) were investigated for the presence and density of live specimens and burrows of T. navalis. The settlement of larval shipworms was studied by exposing experimental fir panels 0.06 m2 in size at 20 stations at water depths between 1 and 2 m for periods of 4 months between July and November. In addition, hydrographic profiles (0–8 m water depth) were obtained at 17 stations in five docks once every month from August to December. Live adult shipworms were found in both fir floating fenders and oak piles at four stations. The largest specimen found was 250 mm long. Shipworm burrows were detected at five stations in almost every wooden structure investigated but their abundances differed significantly: Maximum values were >10,000 m–2 in fir floating fenders, 4,600 m–2 in oak piles and 200 m–2 in fir pier posts. Actual shipworm infestation was detected at three of 16 stations in the exposed fir panels (1–3 burrow holes per panel). Water temperatures and salinities varied considerably during the 4-month investigation period. Temperatures decreased from 19.9°C in August to 0.7°C in December. Salinities ranged from 17.6 in August to 1.1 in November, but only at two lock stations during November and December did value drop below 5, which is regarded as the lethal limit for the larvae of this euryhaline teredinid species. We conclude that T. navalis encounters favourable conditions for growth and reproduction in the harbours of Bremerhaven, at least during summer and autumn, and is a common element of the harbour ecosystem. Therefore, a persistent infestation of all wooden structures after a relatively short period of time seems to be highly probable.

Sea-ice meiofauna was studied during various cruises to the Weddell Sea. Foraminifers dominate (75%) the sea-ice community in terms of numerical abundance while turbellarians dominate (45%) in terms of biomass. Distribution of organisms is patchy and varies considerably between cruises but also between sampling sites within one cruise. The bulk of the meiofauna is concentrated in the lowest parts of the sea ice, especially during winter and autumn. However, in porous summer sea ice, sympagic organisms also occur in high densities in upper and intermediate layers of sea ice. Proto- and metazoans associated with Antarctic sea ice include organisms actually living in sea ice, as well as those on the underside of floes and in the underlying water. The sea-ice habitat serves as a feeding ground, as well as an important nursery for juveniles, providing energy-rich food resources. The ice also constitutes a shelter from predators.

Dynamic temporal and spatial changes of physical, chemical and spatial properties of sea ice pose many challenges to the sympagic community which inhabit a network of brine channels in its interior. Experiments were conducted to reveal the influence of the internal surface area and the structure of the network on species composition and distribution within sea ice. The surface of the brine channel walls was measured via a newly developed method using a fluorogenic tracer. These measurements allowed us to quantify the internal surface area accessible for predators of different sizes, at different ice temperatures and in different ice textures. Total internal surface area ranged from 0.6 to 4 m2 kg−1 ice and declined with decreasing ice temperature. Potentially, 6 to 41% of the area at −2°C is covered by micro-organisms. Cooling from −2 to −6°C drastically increases the coverage of organisms in brine channels due to a surface reduction. A combination of brine channel frequency measurements with an artificial brine network experiment suggests that brine channels ≤200 μm comprise a spatial refuge with microbial community concentrations one to two magnitudes higher than in the remaining channel network. The plasticity of predators to traverse narrow passages was experimentally tested for representative Arctic sympagic rotifers, turbellarians, and nematodes. By conforming to the osmotic pressure of the brine turbellaria match their body dimensions to the fluctuating dimensions of the brine channel system during freezing. Rotifers penetrate very narrow passages several times their body length and 57% their body diameter. In summary, ice texture, temperature, and bulk salinity influence the predatory–prey interactions by superimposing its structural component on the dynamic of the sympagic food web. Larger predators are excluded from brine channels depending on the architecture of the channel network. However, extreme body flexibility allows some predators to traverse structural impasses in the brine channel network.

During two cruises to the Greenland Sea, we studied the abundance and biomass of the sea ice biota in summer and late autumn. The mean calculated biomass of the sympagic community was 0.2 g C m −2 ice. Algae contributed on average 43% to total biomass, followed by bacteria (31%), heterotrophic flagellates (20%), and meiofauna (4%). Diatoms were the main primary producers (60% of total algal biomass), but flagellated cells contributed significantly to the algal biomass. Among the meiofauna, ciliates, nematodes, acoel turbellarians and crustaceans were dominant. Calculated potential ingestion rates of meiofauna (0.6 g C m −2 (120 d) −1 ) are on the same order of magnitude as annual primary production estimates for Arctic multi-year sea ice. We therefore assume that grazing can control biomass accumulation of primary producers inside the sea ice.

Fifty specimens of Notothenia coriiceps caught in Potter Cove, King George Island, were examined for ecto- and endoparasites. Of the 22 parasite species found, 18 were helminths, 2 were hirudineans and 2 were crustaceans. The isopod Aega antarctica and an unidentified hirudinean are reported for the first time from this fish host. Dominant parasites were the adults of Aspersentis megarhynchus, the invasive stage of Corynosoma spp. (cystacanth) and the adults of Macvicaria pennelli, with respective prevalences of infestation of 94, 76 and 74%. The preferred sites of infestation were the pylorus and intestine, where five different larval (nematodes and cestodes) and eight adult (digeneans and acanthocephalans) parasite species were found. No adult nematodes and cestodes were found and no parasites could be isolated from the musculature. The results of the present study are related to previous findings on the parasite fauna of N. coriiceps. The comparison implies a high parasite diversity in this benthic Antarctic fish species. Most parasites found appear to have a wide range of distribution within Antarctic waters together with a low host specificity. Besides its role as final host for several species of trematodes and acanthocephalans, N. coriiceps serves as transmitter of parasite larvae to piscivorous birds and seals. It is concluded that the parasite fauna in Antarctic fish species provides important insights into the different habitat use and trophic relationship of their fish hosts.

The sea ice of both of the Earth's polar regions contains an internal system of delicate brine channels and pockets which serve as a habitat for a variety of organisms including plants and animals. The large standing stock of algae in the ice provides an ample food source for heterotrophic consumers. The sea ice habitat is characterised by low temperatures and correspondingly high salinities. During winter, temperatures as low as-15℃ and salinities as high as 177 psu were recorded in the brine channel system of the upper part of Antarctic sea ice. The tolerance of sympagic organisms to increased salinities is remarkable. Algae grow in salinities of up to 95 psu and also sea ice animals can survive, grow and partly reproduce under high salinities. The foraminifer Neogloboquadrina pachyderma was subjected to a variety of different salinities. Formation of new chambers occurs in salinities of up to 58 psu, specimens survive 82 psu for at least a week, and drastic changes in salinity are tolerated, e.g. direct transfer from 30 to 60 psu or from 60 to 40 psu. Chamber formation rates are slightly slower at higher salinities and the final size of specimens decreases with increasing salinity. Reproduction was never observed in salinities above 50 psu, which corroborates earlier results that N. pachyderma does not reproduce within the sea ice.

Studies on the life strategy of the small calanoid copepod Stephos longipes were carried out in the eastern Weddell Sea during four expeditions (January/February 1985, August 1986, October/December 1986 and April/May 1992). Samples were taken from the water column, the ice/water interface and the sea ice. In winter (August 1986) S. longipes copepodite stage CIV occurred mainly in the upper water layers of the ice covered eastern Weddell Sea, while only nauplii were found in the sea ice. In late winter/early spring (October-December 1986) very low numbers of S. longipes were found in the water column, mainly in the upper 50m, but high numbers occurred immediately below and within the sea ice. Adults dominated in the water column and in the under ice water layer while the sea ice contained nauplii and copepodite stage CI. During summer (January/February 1985) the eastern Weddell Sea was almost entirely free of ice with the exception of fast ice fields atthe ice shelf. During this time S. longipes was concentrated in the upper 50m of the water column and in the ice/water interface where an ice cover was present. Young copepodite stages (CI-CIII) comprised the largest fraction of the population. In autumn (April/May 1992) as new ice began to develop, S. longipes , dominated by copepodite stage CIV, occurred in greatest number within mid-water layers. The abundance of S. longipes in autumn was similar to late winter/early spring highest in the sea ice and lowest in the water column. During all periods of investigation the population structure differed between the various habitats with the youngest population occurring in the sea ice and the oldest in the water column. A younger generation of the S. longipes population appears to overwinter in the sea ice and ice/water interface and an older one in deeper water layers or near the bottom.

In 1988, the short-term response of sea-ice organisms to manipulated changes in snow cover (no snow cover, natural snow cover, natural snow cover + black foil) was investigated in one ice floe located in the East Greenland Current northwest of Svalbard over a period of three weeks. Autotrophic organisms (flagellates and diatoms) were concentrated in the lowermost 30 cm of the floe. In the field without snow cover, the highest diatom concentrations were observed, consisting nearly entirely of pennate forms, together with a maximum bacterial abundance. The community of larger protozoa and smaller metazoa was dominated by ciliates. Under natural conditions the flora consisted of both flagellates and diatoms, while turbellaria were the dominating animals. In the darkened field, the organism concentrations decreased with time. The results indicate that brine drainage, induced by changes in ice temperature, can reduce concentrations of ice organisms over short time scales.

The pelagic foraminifer Neogloboquadrina pachyderma (Ehrenberg, 1861) occurs in new ice, congelation ice, and the underlying water column of the Weddell Sea. Neogloboquadrina pachyderma is incorporated into the ice in large numbers at the time of its formation. The average number of foraminifers per liter of ice was 87 and numbers ranged between 0 and 1,075. Sea ice contained 70 times more foraminifers per unit volume than the underlying water column and on an areal basis the sea ice cover has approximately the same number of specimens as 60 m of underlying water column. The foraminifera are usually incorporated into the ice when it is being formed dynamically and are thus subsequently associated mainly with granular ice. Many foraminifers are able to survive and grow in the ice where algal biomass in winter is high compared to the water column, perhaps indicating an overwintering strategy. Arctic sea ice, on the other hand, is practically devoid of foraminifers. These observations may have implications for paleoceanographers who use N. pachyderma as a tool to reconstruct past surface water conditions.

The “Ice Station POLarstern” (ISPOL) drift experiment was an interdisciplinary study within the perennial sea ice of the western Weddell Sea that brought together scientists from 11 countries. The primary goal was the monitoring of physical and biogeochemical interactions between atmosphere, ice and ocean at the transition from austral winter to summer. Special emphasis was set on the processes controlling sea-ice melting and the onset of phytoplankton bloom. The ISPOL observations complement the study of the seasonal sea ice–ocean cycle in the western Weddell Sea, initiated by the summer to winter drift of Ice Station Weddell-1 (ISW-1) in 1992. This volume contains a collection of papers that range from the atmosphere to the deep ocean, from micro- to macro-scales, from physics to biology with their interactions investigated during the 36 days of the ISPOL experiment.

Large numbers of acantharian cysts, up to more than 30 individuals per m3, were collected during the austral summer (January–February) 1985 in the Weddell Sea, Antarctica by a multiple open-closing plankton net system. Stations were sampled 17 days later in the season and revealed slightly higher abundances of cysts. Samples collected in the same region during winter and spring 1986 (July–November) contained no acantharian cysts. The numbers of cysts decreased from open ocean conditions to locations close to the ice shelf coast. Cysts were most abundant in water depths between 100 and 300 meters. The morphology of the cysts, constructed from differently shaped strontium sulfate plates or from amorphous strontium sulfate, is described and the taxonomy of the different types discussed.

The distribution and structure of zoobenthic communities have been investigated in the northern North Atlantic. The principal goal of these studies is to assess the degree to which benthic community patterns depend on and/ or mediate carbon flux between the pelagic and benthic realms, as well as between seabed, sediment-water interface and benthic boundary layer. A common rationale is that these patterns integrate the impact of environmental factors over longer periods of time and reflect relatively long-lasting or predictably recurrent environmental states, thus providing clues to the relative significance of potential community determinants on a time scale of months to years. Since 1992, several meso-scale field studies have been carried out in three regions at the East Greenland continental margin between 68° N and 81° N at water depths ranging from 40 to 3,700 m. A suite of sampling methods was employed (corers, trawls, seabed imaging) to adequately probe various benthic community fractions, such as foraminifers, poriferans, macrobenthic endofauna, peracarid crustaceans and megabenthic epifauna.A depth zonation in the faunal composition, accompanied by a shift in the predominance of different feeding types and a significant decline in biomass and abundance by as much as two and three orders of magnitude was the most conspicuous general pattern detected. However, in terms of species richness, no common trend for water depth or latitude was perceivable. The general depth zonation of the macrobenthos as well as the spatial concordance of high macrobenthic abundance and biomass with relatively productive hydrographic zones, such as marginal ice zones, polynyas and anti-cyclonic gyres, provide evidence for the importance of water column processes and, hence, for subsequent food availability as major determinants for benthic assemblages and the significance of pelago -benthic coupling in the study area in general. However, for megafaunal species such as echinoderms, community patterns on a 10-1an scale and the dispersion of organisms on a 100-m scale, are best explained by seafloor properties. There is no evidence of direct pelago-benthic coupling, irrespective of water depth. These contrasting findings emphasize that the relative importance of potential community determinants can change with both spatial scale and life traits, e.g. body size, mobility and feeding ecology, of the organisms considered.

Russian and German scientists have investigated the extreme environmental system in and around the Laptev Sea in the Siberian Arctic. For the first time a major comprehensive research program combining the efforts of several projects addressed both oceanic and terrestrial processes, and their consequences for marine and terrestrial biota, landscape evolution as well as land-ocean interactions. The primary scientific goal of the multidisciplinary program was to decipher past climate variations and their impact on contemporary environmental changes. Extensive studies of the atmosphere, sea ice, water column, and sea-floor on the Laptev Sea Shelf, as well as of the vegetation, soil development, carbon cycle, permafrost behaviour and lake hydrology, and sedimentation on Taymyr Peninsula and Severnaya Zemlya Archipelago were performed during the past years under a framework of joint research activities. They included land and marine expeditions during spring (melting), summer (ice free), and autumn (freezing) seasons. The close bilateral cooperation between many institutions in Russia and Germany succeeded in drawing a picture of important processes shaping the marine and terrestrial environment in northern Central Siberia in Late Quaternary time. The success of the projects, which ended in late 1997, resulted in the definition and establishment of a new major research effort which will concentrate on establishing a better understanding of the paleoclimatic and paleoenvironmental record of the area. This is important because it allows to be able to judge rates and extremes of potential future environmental changes.

This contribution focuses on coupling processes between the three major Arctic marine realms, the sea ice, the pelagic and the benthic habitat. Physically and biologically mediated interactions cause specific Arctic growth regimes, which are—to a large extent — due to the seasonal changes of the Arctic sea ice cover. Based on the described interactions we recommend combined studies of ice extent and ocean colour together with field measurements of organic biomass, production and diversity for a better understanding of relevant biological processes in Arctic seas.

The sea ice which covers large areas of the polar regions plays a major role in the marine ecosystem of both the Arctic and Southern Oceans. Not only do warmblooded animals depend on sea ice as a platform, but the sympagic organisms living internally within the sea ice or at the interfaces ice/snow and ice/water provide a substantial part of the total primary production of the ice covered regions. In addition sea ice organisms are an important food source for a variety of pelagic animals and may initiate phytoplankton spring blooms after ice melt by seeding effects. Sea ice organisms often are enriched by some orders of magnitude if the same volume of melted ice is compared to that of the underlying water column. Three hypotheses try to explain this discrepancy and are discussed. Investigations on the nutrient chemistry within the sea ice system and in-situ observations still are rare. Intense growth of sympagic organisms can result in nutrient deficiencies, at least in selected habitats. Advances in endoscopie methods may lead to a better understanding of the life within the sea ice.

The distribution of ice organisms was investigated in Fram Strait in May 1988 during the ARK V/1 expedition on RV Polarstern. Over a 3 week period the abundances of bacteria, diatoms, auto- and heterotrophic flagellates as well as various groups of meiofauna organisms were observed in the lowermost 30 cm of an ice floe. Data were obtained from three experimental fields under three different light regimes as a result of manipulations of the snow cover. The application of multivariate factor analysis on this time series data set resulted in the characterization of four succession stages of an Arctic sea ice community: 1) the diatom bottom assemblage, 2) the mixed autotrophic assemblage, 3) the mixed auto- and heterotrophic supra-bottom assemblage, and 4) the heterotrophic supra-bottom assemblage. The two most abundant meiofauna groups (Turbellaria, Ciliata) showed different preferences according to algal distribution. While turbellarians were most abundant in samples with mixed populations of diatoms and flagellates, ciliates reached their abundance maxima in samples dominated by diatoms, suggesting different prey selections. We have developed a model for the explanation of the spatial separation of auto- and heterotrophic organisms, highlighting the possible role of DOC production by ice algae and DOC transport with brine flow.

Polar regions are covered by extensive sea ice that is inhabited by a variety of plants and animals. The environments where the organisms live vary depending on the structure and age of the ice. Many terms have been used to describe the habitats and the organisms. We here characterize the habitats and communities and suggest some standard terms for them. We also suggest routine sampling methods and reporting units for measurements of biological and chemical variables. © 1992 Springer-Verlag GmbH & Co. KG.

The sea ice does not only determine the ecology of ice biota, but it also influences the pelagic systems under the ice cover and at ice edges. In this paper, new estimates of Arctic and Antarctic production of biogenic carbon are derived, and differences as well as similarities between the two oceans are examined. In ice-covered seas, high algal concentrations (blooms) occur in association with several types of conditions. Blooms often lead to high sedimentation of intact cells and faecal pellets. In addition to ice-related blooms, there is progressive accumulation of organic matter in Arctic multi-year ice, whose fate may potentially be similar to that of blooms. A fraction of the carbon fixed by microalgae that grow in sea ice or in relation to it is exported out of the production zone. This includes particulate material sinking out of the euphotic zone, and also material passed on to the food web. Pathways through which ice algal production does reach various components of the pelagic and benthic food webs, and through them such top predators as marine mammals and birds, are discussed. Concerning global climate change and biogeochemical fluxes of carbon, not all export pathways from the euphotic zone result in the sequestration of carbon for periods of hundreds of years or more. This is because various processes, that take place in both the ice and the water column, contribute to mineralize organic carbon into CO2before it becomes sequestered. Processes that favour the production and accumulation of biogenic carbon as well as its export to deep waters and sequestration are discussed, together with those that influence mineralization in the upper ice-covered ocean. © 1992 Springer-Verlag GmbH & Co. KG.

Under controlled laboratory conditions the influence of increased water fertility was tested in four spinose planktonic foraminifers. Among other things, increased water fertility may be characterized by high prey densities and longer wavelength, low light conditions. Normally, a larger test is formed at higher feeding rates. This is shown most distinctly in Globigerinella siphonifera (d'Orbigny). The effect of increased food availability on test size of Orbulina universa d'Orbigny is larger at lower temperatures, a condition that prevails during upwelling events. For logistical reasons, the mean final size of Globigerinoides sacculifer (Brady) does not show a consistent tendency with feeding rate. Globigerinoides ruber (d`Orbigny) does not tolerate high levels of brine shrimp and was thus not kept at higher feeding levels.Globigerinella siphonifera and O. universa reach smaller shell sizes under light conditions that characterize fertile regions (yellow-green) relative to typical open ocean light conditions (blue). In contrast, G. ruber attains smaller shell sizes under blue light relative to yellow-green light. Again, G. sacculifer does not show a clear trend with respect to final test size under normal and upwelling light.The effect of longer wavelength light counteracts and overrules the effect of increased prey capture rates in the investigated symbiont bearing species. This phenomenon is explained as photosynthesis-limited host respiration. The extent to which the light effect counteracts the effect of feeding probably depends on habitat to which the species are originally adapted. Qualitative and qualitative pigment analyses suggest that G. ruber lives shallow, G. sacculifer lives deeper and that G. siphonifera has the deepest habitat. Data from the literature indicate that O. universa lives at intermediate depth between G. siphonifera and G. sacculifer. As G. siphonifera is somehow adapted to low intensity longer wavelength light, the counter effect of low intensity and longer wavelength light is minimized in this species. As a result, the effect of increased feeding rate is most pronounced in this species.Fertile water is found in upwelling settings and in areas where rivers enter into the ocean. Comparison of sediments from fertile regions and neighboring open ocean sites shows that symbiont bearing planktonic foraminifers attain smaller shell sizes in the upwelling area off Benguela but that larger shells are found in the Zaire river plume. Due to the small quantity of reference sediment, statistically significant differences were found only for O. universa. The different response is explained as the result of limited respiration in upwelling areas because of lower than usual oxygen levels.The morphology of the final chamber is influenced by both light quality and feeding rate. At higher feeding rates the number of sac-like phenotypes is decreased. Yellow-green light induces more kummerform morphologies in G. sacculifer, G. ruber, and G. siphonifera and increases second sphere formation in O. universa. Light quality effects the terminal morphology to a larger extent than prey capture rates do. Unfortunately, these trends could not be confirmed in our reference sediment due to the low number of kummerforms and sac-like chambers.Water fertility also influences the fractionation of stable oxygen isotopes. It is concluded that G. sacculifer does not secrete carbonate in equilibrium with ambient seawater. Isotopically lighter tests are constructed under longer wavelength light conditions and they tend to get heavier with increasing prey capture rates. Specimens with sac-like chambers are lighter than normalform specimens whereas kummerform types are heavier than normalform types.

Seasonal and spatial variation in sea ice organisms were studied in the Weddell Sea region during the austral summer 1985 and winter and spring 1986. Sea ice cores were collected from 22 stations. Winter values for chlorophyll a measured per 10 cm segment of drilled ice core ranged between 0 and 49 μgl−1 (mean 3.4) during July to September and between 0 and 450 μgl−1 (mean 7.6) during October to December, while mean summer values were considerably higher (mean 34.5) with a maximum of 2220 μgl−1. Increasing numbers of sea ice organisms were also observed in sea ice cores from stations reoccupied after several weeks in spring. Samples taken later in season (November compared to October) revealed a higher biomass and more organisms. Algal biomass and absolute numbers of sea ice organisms including foraminifers, copepods and ciliates decreased along a transect from the ice edge towards the continent and along the eastern Weddell Sea coast from northeast to southwest. However, the distribution of organisms was patchy and replicate cores taken only a few centimeters apart contained numbers of organisms which differed considerably. This is partly due to different ice formation processes which show both small and mesoscale variation and may account for the observed abundances of ice organisms.

Two types of morphogenetic patterns of development are described: (1) a sequence commencing with lattice development followed by rim growth within the lattice pores and culminating in lattice-like cap projections at the poles of the bilocular shell as in the development of Didymocyrtis tetrathalamus tetrathalamus , and (2) a pattern of porous plate deposition followed by ridge lattice growth between the pores, culminating in a rim growth producing the outer porous wall of the spherical shell as in Hexalonche amphisiphon . Morphometric data are presented for major shell parameters and pore shape in the two species as a means of documenting the skeletal diversity found in populations of these radiolarian species.

The remarkable originality of Dos Passos's Manhattan Transfer (1925) has been long recognized. From Sinclair Lewis's early appreciative essay onwards, the novel's significant advance over Dos Passos's three previous novels, its break with constricting convention, and its technical boldness have been repeatedly noted. Dos Passos's broad concern remains that of the traditional realist–the heavily itemized portraiture of urban social life–but in Manhattan Transfer that portraiture is energized and given fresh impact by new modes of description and new principles of narrative structure. These innovations have customarily been traced to the influence of modernist experimentation in the novel, and Dos Passos's debts to James Joyce, Gertrude Stein and Marcel Proust have been established. Yet an explanation of Dos Passos's conception of form which confines itself to literary modernism alone must be regarded as incomplete. Dos Passos's heightened visual sense and the marked painterly and cinematic qualities of his work indicate that it is to the twentieth-century pioneers in the visual arts, as well as to the pioneers in fiction, that we must look for formative influences.Dos Passos enjoyed a lifelong interest in the visual arts. After Harvard he went to Spain to study architecture, and at one time as a young man he was unsure whether to choose fine art or literature as his main avenue of creative expression.

The planktonic foraminiferGlobigerinoides sacculifer (Brady) was maintained in the laboratory under different temperature (19.5–29.5°C) and salinity (33 and 36‰) regimes. The light and feeding conditions were adjusted to the open ocean environment. The light intensity and quality corresponded to a water depth of 10–30 m and the specimens were fed daily. Specimens were raised from a mean initial size of approximately 220–240 μm to the reproductive mean size ranging from 521 μm to 657 μm according to the different temperature and salinity regimes. The survival time decreased with increasing temperature relatively independent of salinity. The growth rate decreased with decreasing temperatures but significantly only at the lowermost temperature range. The general vitality increased with increasing salinity, partially indicated by more chamber formations of specimens of the 36‰ salinity group in comparison to those of the 33‰ salinity group. The different phenotypes of the final chamber and the different morphologies ofG. sacculifer are discussed.

A unique property of polythalamous foraminifers among protozoans is the preservation of their entire life-history in the sequential arrangement of chambers forming the test. By tracing the chamber-by-chamber growth of Globigerinoides sacculifer (Brady) and Globigerinoides ruber (d'Orbigny), marked changes in skeletal morphology, quantified test parameters and vital behavior were observed. Comparison with other globigerinid species shows these changes to reflect a basic, phased pattern of globigerinid growth. We propose an ontogenetic concept defining the prolocular, juvenile, neanic, adult and terminal stages of ontogeny. During ontogeny, species show a diagnostic morphology enabling identification of each stage at the species level, except for most prolocular and earliest juvenile stages. During the late neanic stage morphological features initially develop that are currently used to characterize a species. The proposed ontogenetic concept has major applications in planktonic foraminiferal micropaleontology. Comparative ontogeny offers a new and comprehensive means to establish a “natural” classification and taxonomy. Also, it provides a tool to reliably infer phylogenetic lineages. Once the pre-adult morphology of large-sized species is known, species that are small-sized at maturity can be recognized. As a result, faunal analysis of the fine fraction of foraminiferal samples becomes feasible, thus permitting improved resolution in biostratigraphic and paleoceanographic studies.

Sergei Eisenstein, the Russian film-maker, called An American Tragedy “ as broad and shoreless as the Hudson … as immense as life itself.” It allowed, he wrote, “ almost any point of view of itself.” This rare quality of multi-faceted massiveness has fathered a large number of critical studies, which all vary in their reading of the text and the significance they attribute to Dreiser's protagonist, Clyde Griffiths. For Irving Howe, Clyde represents “ the passivity, rootlessness and self-alienation of urban man,” while for F. O. Matthiessen, he is “ a victim of the contemporary American dream.” Richard Lehan views him deterministically as “ a young man … caught in and finally destroyed by the crush of conflicting forces,” while Ellen Moers generalizes him into “ the Everyman of desire.” These interpretations acknowledge Clyde's representative stature, but make only imprecise gestures towards its origins. The vagueness they suffer from has its root in an individualist emphasis upon the character and fate of the protagonist and a corresponding lack of specificity in describing the social framework with which that character interacts. Eisenstein regarded Clyde's crime as “ the sum total of those social relations, the influence of which he was subjected to at every stage of his unfolding biography and character.” An analysis of these “ social relations,” particularly as elaborated in the closely integrated themes of youth, class, and consumerism, is a prerequisite to a more exact identification of Clyde's social representativeness.

Sea ice cores were obtained from eleven fast ice stations and one floe in the Weddell Sea, Antarctica in January–February 1985. All cores from the north eastern part of the Weddell Sea contained numerous living and dead planktic foraminifers of the species Neogloboquadrina pachyderma (Ehrenberg), while cores drilled in southern parts were barren of foraminifers with one exception. Foraminiferal abundances were variable, with numbers up to 320 individuals per liter melted sea ice. Distribution of foraminifers appears to be patchy, parallel cores taken less than 30 cm apart contained numbers which varied considerably. On the other hand, three cores taken on a transect each more than 3 km apart showed striking similarities. In general, small dead tests were found in the upper parts of the sea ice cores while large living individuals mainly occurred in lower sections. Abundant diatoms probably serve as a food source for the foraminifers. Correlation of foraminiferal abundance with salinity, chlorophyll and nutrient profiles are inconsistent. The possible mechanism of incorporation of N. pachyderma into the ice is discussed.