Ice Fauna Research Articles

Ice algae in current water-ice environmental condition of the Arctic Ocean

In the Arctic Ocean (AO) of today, there are noticeable changes in the composition and structure of biological communities inhabiting the water-ice environment. Over the past two decades, a decrease in the number of species of the sea ice flora and fauna has been noted in the central regions of the AO due to the changing physical environment of their habitat. In view of the current climatic instability in the AO, it is important to monitor and evaluate their composition, structure and dynamics of development. It is also important to preserve the methods of processing the materials collected in order to compare the state of the water-ice biota on similar spatial and temporal scales of the basin. In the present study, centric and pennate diatoms dominating in ice floristic communities were selected as indicators of changes. The aim of the work is to analyze the physical state of the water-ice environment and the species composition of ice diatoms based on the materials of the expeditions within the NABOS program at the Research Vessel (R/V) “Akademik Treshnikov” in the Arctic Basin in 2018 and 2021. The field work included observations of the state of the sea-ice cover in the area of the expeditions, the selection of ice cores to assess the salt composition and species composition of the algae, as well as CTD-sounding of the under ice — water layer. The analysis of the materials collected showed significant differences in the species composition and abundance of algae between the seasons, which indicates the formation of independent floristic communities in the current conditions of unstable physical environment in the central regions of the AO, which confirms the previously obtained results in the period 2007–2015. The materials under discussion were obtained in a short period of time and in limited spaces in the zones of production of annual ice in the waters of the shelf seas and zones of removal to the central regions of the AO. At the same time, short-term observations provide “instant” information about the qualitative and quantitative state of sea-ice biological communities. In order to obtain reliable estimates, long-term observations are needed, which may be organized in the near future based on new logistical approaches to the study of the marine Arctic.

Characterization of the Biodiversity of Modern Sea Ice in the North Pole Region

The aim of this work was to analyze the observation data on the dynamics of the species composition of ice flora and fauna in the polar region of the Arctic Ocean. The analysis was based on the materials obtained by the Pan-Arctic ice camp expedition in April 2007–2011 and 2015 [1]. We indicated the dynamics of the species composition of flora by diatoms living in the ice, and of fauna by amphipods and copepods with habitats allocated to the bottom ice surface. The dynamics of the species composition of biota is analyzed in this work without specification of its natural or anthropogenic factors.

Variability of the fauna within drifting sea ice floes in the seasonal ice zone of the Southern Ocean during the austral summer

Sea ice covering the seasonal ice zone in the Southern Ocean contains micro-organisms (sea ice biota). Studies of sea ice biota have mostly been conducted on the land-fast ice and large ice floes, despite most sea ice in the Southern Ocean being seasonal and drifting ice types. We sampled 17 drifting sea ice floes in the marginal ice zone off Adélie Land, East Antarctica, in January 2013 and 2014. We found high densities of copepods such as Harpacticoida species (18,787 ± 50,647 inds.m−3), Paralabidocera antarctica (1773 ± 6370) and their nauplii (69,943 ± 149,607), as well as foraminiferans (193,869 ± 408,721) within ice. Variability in the animal assemblages among the different ice floes was observed. Cluster analysis of samples based on the assemblage of sea ice fauna revealed two major groups, which were divided by the year of the sampling, and were dominated by harpacticoid nauplii and foraminiferans, respectively. Sea ice trajectory and drifting duration estimated from satellite data were different for both years, although the origin of the sea ice was in the same bay. This study suggests that the variability of fauna among sea ice floes may reflect the continuance period of ice formation and the trajectory from where they originated.

Sympagic-pelagic-benthic coupling in Arctic and Atlantic waters around Svalbard revealed by stable isotopic and fatty acid tracers

Stable isotope and fatty acid trophic markers (FATMs) were used to assess carbon flow and trophic structures of sympagic, pelagic and benthic communities in high-Arctic Svalbard. Three regions were sampled: Northwest Svalbard – dominated by Atlantic water (AtW) and limited seasonal sea ice; Northern Svalbard – dominated by AtW and perennial sea ice; and Northeast Svalbard – dominated by Arctic water (ArW) and extensive seasonal sea ice. Three to four trophic levels (TL) were found in the three habitats, with a dominance of omnivores (TL = 2.4–2.7). Ice fauna relied on phytoplankton and ice algae, zooplankton primarily on phytoplankton, while benthos relied on ice algae/refractory material. Ice fauna (mean 39%; range 17–62%) and benthos (mean 25%; range 11–65%) had high proportions of diatom-FATMs, while zooplankton had equally high diatom- and Phaeocystis/dinoflagellate-FATMs (mean 11% and 15%, respectively). Calanus-FATMs were prominent in carnivorous ice fauna (up to 28%) and zooplankton (up to 38%), but also in benthic invertebrates (up to 41%). Ice fauna biomass was low. Biomass of zooplankton and benthic infauna were variable, but positively correlated to each other (r 2=0.89; p<0.01) and sedimentary pigment concentrations (r 2>0.40; p<0.05). The coinciding peak biomasses of zooplankton and benthos in Northeast Svalbard can be explained by allochthonous organic matter of ice algal origin and highly specialized Arctic zooplankton utilizing both ice algae and phytoplankton carbon sources.

Distribution patterns of micro- and meso-zooplankton communities in sea ice regions of Lützow-Holm Bay, East Antarctica

In the Southern Ocean, zooplankton research has focused on krill and macro-zooplankton despite the high densities of micro- and meso-zooplankton. We investigated their community structure in relation to different sea ice conditions around Japan’s Syowa Station in Lutzow-Holm Bay, in the summers of 2011 and 2012. Zooplankton samples were collected using vertical hauls (0–150 m), with a closing net of 100-μm mesh size. The results of cluster analysis showed that the communities in this region were separated into fast ice, pack ice, and open ocean fauna. The fast ice fauna had lower zooplankton abundance (393.8–958.9 inds. m−3) and was dominated by cyclopoid copepods of Oncaea spp. (54.9–74.8 %) and Oithona similis (6.6–19.9 %). Deep-water calanoid copepods were also found at the fast ice stations. Pack ice and open ocean fauna had higher zooplankton abundance (943.6–2,639.8 inds. m−3) and were characterized by a high density of foraminiferans in both years (6.6–61.9 %). Their test size distribution indicated that these organisms were possibly released from melting sea ice. The pteropod Limacina spp. was a major contributor to total abundance of zooplankton in the open ocean zone in 2012 (26.4 %). The physical and/or biological changes between 2 years may affect the abundance and distribution of the dominant zooplankton taxa such as cyclopoid copepods, foraminiferans, and pteropods. Information on the relationships between the different species associated with sea ice will help to infer the possible future impacts of climate change on the sea ice regions.

Retention of ice-associated amphipods: possible consequences for an ice-free Arctic Ocean

Recent studies predict that the Arctic Ocean will have ice-free summers within the next 30 years. This poses a significant challenge for the marine organisms associated with the Arctic sea ice, such as marine mammals and, not least, the ice-associated crustaceans generally considered to spend their entire life on the underside of the Arctic sea ice. Based upon unique samples collected within the Arctic Ocean during the polar night, we provide a new conceptual understanding of an intimate connection between these under-ice crustaceans and the deep Arctic Ocean currents. We suggest that downwards vertical migrations, followed by polewards transport in deep ocean currents, are an adaptive trait of ice fauna that both increases survival during ice-free periods of the year and enables re-colonization of sea ice when they ascend within the Arctic Ocean. From an evolutionary perspective, this may have been an adaptation allowing success in a seasonally ice-covered Arctic. Our findings may ultimately change the perception of ice fauna as a biota imminently threatened by the predicted disappearance of perennial sea ice.

Zooplankton boom and ice amphipod bust below melting sea ice in the Amundsen Gulf, Arctic Canada

Early summer in the Arctic with extensive ice melt and break-up represents a dramatic change for sympagic–pelagic fauna below seasonal sea ice. As part of the International Polar Year-Circumpolar Flaw Lead system study (IPY-CFL), this investigation quantified zooplankton in the meltwater layer below landfast ice and remaining ice fauna below melting ice during June (2008) in Franklin Bay and Darnley Bay, Amundsen Gulf, Canada. The ice was in a state of advanced melt, with fully developed melt ponds. Intense melting resulted in a 0.3- to 0.5-m-thick meltwater layer below the ice, with a strong halocline to the Arctic water below. Zooplankton under the ice, in and below the meltwater layer, was sampled by SCUBA divers. Dense concentrations (max. 1,400 ind. m−3) of Calanus glacialis were associated with the meltwater layer, with dominant copepodid stages CIV and CV and high abundance of nauplii. Less abundant species included Pseudocalanus spp., Oithona similis and C. hyperboreus. The copepods were likely feeding on phytoplankton (0.5–2.3 mg Chl-a m−3) in the meltwater layer. Ice amphipods were present at low abundance (<10 ind. m−2) and wet biomass (<0.2 g m−2). Onisimus glacialis and Apherusa glacialis made up 64 and 51% of the total ice faunal abundance in Darnley Bay and Franklin Bay, respectively. During early summer, the autochthonous ice fauna becomes gradually replaced by allochthonous zooplankton, with an abundance boom near the meltwater layer. The ice amphipod bust occurs during late stages of melting and break-up, when their sympagic habitat is diminished then lost.

Seasonal food web structures and sympagic–pelagic coupling in the European Arctic revealed by stable isotopes and a two-source food web model

We simultaneously followed stable carbon ( δ 13C) and nitrogen ( δ 15N) isotopes in a two-source food web model to determine trophic levels and the relative importance of open water- and ice-associated food sources (phytoplankton vs. ice algae) in the lower marine food web in the European Arctic during four seasons. The model is based upon extensive seasonal data from 1995 to 2001. Phytoplankton, represented by samples of particulate organic matter from open water (Pelagic-POM) and ice algae, represented by samples from the underside of the ice (Ice-POM), were isotopically different. Ice-POM was generally dominated by the typical ice diatoms Nitzschia frigida and Melosira arctica and was more enriched than Pelagic-POM in 13C ( δ 13C = −20‰ vs. −24‰), but less enriched in 15N ( δ 15N = 1.8‰ vs. 4.0‰). However, when dominated by pelagic algae, Ice-POM was enriched in 13C and 15N similarly to Pelagic-POM. The derived trophic enrichment factors for δ 15N (Δ N = 3.4‰) and δ 13C (Δ C = 0.6‰) were similar in both pelagic and sympagic (ice-associated) systems, although the Δ C for the sympagic system was variable. Trophic level (TL) range for zooplankton (TL = 1.8–3.8) was similar to that of ice fauna (TL = 1.9–3.7), but ice amphipods were generally less enriched in δ 15N than zooplankton, reflecting lower δ 15N in Ice-POM compared to Pelagic-POM. For bulk zooplankton, TLs and carbon sources changed little seasonally, but the proportion of herbivores was higher during May–September than in October and March. Overall, we found that the primary carbon source for zooplankton was Pelagic-POM (mean 74%), but depending on species, season and TL, substantial carbon (up to 50%) was supplied from the sympagic system. For bulk ice fauna, no major changes were found in TLs or carbon sources from summer to autumn. The primary carbon source for ice fauna was Ice-POM (mean 67%), although ice fauna with TL > 3 (adult Onisimus nanseni and juvenile polar cod) primarily utilized a pelagic food source.

Ciliated epibionts on the Arctic sympagic amphipod Gammarus wilkitzkii as indicators for sympago–benthic coupling

In September 2003 specimens of the sympagic amphipod Gammarus wilkitzkii were sampled in drifting pack ice above 50 m water depth and in the pelagic/benthic environment beneath in the coastal waters off Svalbard (Norway). Abundance values ranged between 1.5 and 8 individuals m−2 for the pelagic/benthic and the sympagic environments, respectively, and showed corresponding sex ratios of 1:1.4, favoring males. In the ice a significantly higher number of juveniles prevailed. In contrast, ovigerous females were more abundant among pelagic/benthic living specimens. Approximately 25% of the individuals hosted ciliated epibionts of the genera Ephelota, Cryptacineta, Acineta, Podophrya (all suctoria), and Epistylis (peritrichia). Cryptacineta and Ephelota were the most abundant epibionts on this amphipod species. Female specimens of G. wilkitzkii showed the highest degree of infestation (>2,100 individual epibionts per amphipod specimen: indE/A) followed by juveniles (>1,200 indE/A) and males (>220 indE/A). Highest densities of epibionts were found on anterior body parts with the antennae bearing up to 130 individuals. This is the first sighting of epibionts on crustacea from the sympagic environment. We interpret them as biomarkers that indicate the existence of sympago–benthic coupling processes between the ice and the underlying waters and the seafloor. The population structure and the proportion of infested specimens are equal for the amphipods sampled from both the sympagic and the pelagic/benthic environment, indicating the existence of exchange (coupling) processes between the two habitats. Considering the annual ice cycle, local ice drift patterns, and the shallow water depth in the sampling area, we hypothesize that ice amphipods spend ice-free periods near the seafloor where they may serve as basibionts for protozoans and eventually re-colonize the ice with the onset of ice formation. Our observations strongly emphasize that shallow coastal areas serve as both retention (rather than sink) areas for ice fauna during ice-free periods, and as stepping-stones for re-colonizing the ice when the ice is formed in winter.

Enantiomer Fractions of Organic Chlorinated Pesticides in Arctic Marine Ice Fauna, Zooplankton, and Benthos

Stereoisomers of chiral chlorinated pesticides (alpha-HCH (HCH = hexachlorocyclohexane), trans- and cis-chlordane, MC5, o,p'-DDT) were quantified in arctic marine invertebrates (ice-associated amphipods Gammarus wilkitzkii, pelagic copepods Calanus hyperboreus, krill Thysanoessa inermis, and amphipods Themisto libellula, and benthic amphipods Paramphithoe hystrix). Enantiomer fractions (EFs) were calculated to investigate the influence of habitat, geographic area, and diet on selective bioaccumulation of the (-)- or (+)-enantiomer. Depletion of the (+)-alpha-HCH enantionmer increased from ice fauna to zooplankton to benthos, corresponding to previous reports of EF variations with depth. Chlordanes and o,p'-DDT also showed the strongest enantioselective bioaccumulation in benthic amphipods and less so in zooplankton and ice fauna, which had closer to racemic EFs. Neither diet nor geographic area explained EF differences among samples. Nonracemic EFs in benthos may be related to stereoselective biotransformation, but is most likely reflecting vertical distribution of EFs in the water column and sediments, as demonstrated earlier for alpha-HCH in the Canadian and European Arctic.

Origin and fate of ice fauna in the Fram Strait and Svalbard area

The biomass of arctic sympagic (ice associated) amphipods from multiyear ice sampled in September and October 2002 in the Fram Strait between Greenland and Svalbard was approxi- mately 10% lower than in previous recordings (0.4 ± 0.17 g wet mass m -2 ). Gammarus wilkitzkii Birula and Apherusa glacialis Hansen were the most numerous species at the 4 ice stations, reaching average densities of 7 ± 6 and 4 ± 3 ind. m -2 , respectively. Along the marginal ice zone, sympagic amphipods are released to the water column and rapidly sink towards the seafloor. Amphipod densi- ties in the surface waters ranged between 0 and 9 ind. m -2 for the 0 to 25 m water layer and between 0 and 5 ind. m -2 for the 25 to 50 m water layer. In contrast to our observations in sea ice, the most abundant species in the water beneath the ice was Onisimus glacialis Sars. Laboratory experiments indicated that O. glacialis reaches 100 m water depth within approximately 80 min, and G. wilkitzkii sinks twice as fast. Using hydrographical data, air temperature recordings and simulated trajectories, we estimated the origin and drift route of the investigated ice fields and related their recent and long- term history to our findings. The driving forces for the release of ice amphipods are ice breakup and swell, along with the structural decay of the ice due to intense melting. Comparison of various data sets on the standing stock of sympagic amphipods in the ice north of Svalbard suggests that previous calculations estimating the loss of ice-bound bio-energy in the Fram Strait and Svalbard area are overestimations and apply only to certain climatic regimes. Based on our present understanding of (1) the circulation system and ice drift patterns in the Fram Strait, and (2) the impact of thermo- and hydrodynamics on the sympagic ecosystem along the ice margin, we have identified continental shelves and coastal areas as settling and retention zones for released ice fauna.

Seasonal variability in abundance, respiration and lipid composition of Arctic under-ice amphipods

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 292:251-262 (2005) - doi:10.3354/meps292251 Seasonal variability in abundance, respiration and lipid composition of Arctic under-ice amphipods Iris Werner1,*, Holger Auel2 1Institute for Polar Ecology, Wischhofstraße 1–3, Gebäude 12, 24148 Kiel, Germany2Marine Zoology (FB2) University of Bremen, PO Box 330440, 28334 Bremen, Germany *Email: iwerner@ipoe.uni-kiel.de ABSTRACT: The Arctic under-ice amphipods Apherusa glacialis, Onisimus glacialis, O. nanseni and Gammarus wilkitzkii are autochthonous below the pack ice, i.e. they occur in this habitat during all seasons. In this study, seasonal dynamics in abundance were only evident in A. glacialis. Respiration rates did not differ significantly between summer and winter in any species, indicating that the under-ice habitat is a comparatively stable environment in terms of seasonal variations. The assessment of total lipids and fatty acid biomarkers revealed differences in feeding behaviour and overwintering strategy among the amphipod species. A. glacialis is strictly herbivorous, feeding on ice-algae at the underside of the ice during the productive season. The species overwinters in an active state, fuelled at least partly by internal lipid reserves stored during summer. O. glacialis switches from a predominantly herbivorous diet in summer to metazoan prey, including planktonic copepods, in winter, so that lipid catabolism is less important to winter survival. The congener O. nanseni relies on an opportunistic omnivorous diet throughout the year, with a higher proportion of metazoan prey during summer compared to O. glacialis. G. wilkitzkii is able to exploit a wide spectrum of food sources, from predominantly ice algae in summer to more ice fauna and planktonic copepods in winter. This species partly meets its energy requirements by using internal lipid reserves during winter. KEY WORDS: Seasonal dynamics · Overwintering strategies · Cryo-pelagic coupling · Arctic foodweb · Apherusa glacialis · Onisimus glacialis · Onisimus nanseni · Gammarus wilkitzkii Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 292. Online publication date: May 12, 2005 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2005 Inter-Research.

Food web magnificaton of persistent organic pollutants in poikilotherms and homeotherms.

Food web magnification of persistent organic pollutants (POPs) was determined for the Barents Sea food web using 615N as a continuous variable for assessing trophic levels (TL). The food web investigated comprised zooplankton, ice fauna and fish (poikilotherms, TL 1.7-3.3), and seabirds and seals (homeotherms, TL 3.3-4.2), with zooplankton representing the lowest and glaucous gull the highest trophic level. Concentrations of lipophilic and persistent organochlorines were orders of magnitude higher in homeotherms than in poikilotherms. These compounds had significantly higher rates of increase per trophic level in homeotherms relative to poikilotherms, with the highest food web magnification factors (FWMFs) for cischlordane and p,p'-DDE. Some compounds, such as transnonachlor and HCB, had similar rates of increase throughout the food web, whereas compounds that are more readily eliminated (gamma-HCH) showed no relationship with trophic level. It is preferable to calculate FWMFs with regard to thermal groups, because the different energy requirements and biotransformation abilities between poikilotherms and homeotherms may give different rates of contaminant increase with trophic level. When biomagnification is compared between ecosystems, FWMFs are preferable to single predator-prey biomagnification factors. FWMFs represent a trophic level increase of contaminants that is average for the food chain rather than an increase for a specific predator-prey relationship. The Barents Sea FWMFs were generally comparable to those determined for marine food webs with similar food chain lengths in the Canadian Arctic.

Differences in contamination load between pelagic and sympagic invertebrates in the Arctic marginal ice zone: influence of habitat, diet and geography

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 235:157-169 (2002) - doi:10.3354/meps235157 Differences in contamination load between pelagic and sympagic invertebrates in the Arctic marginal ice zone: influence of habitat, diet and geography K. Borgå1,2,*, G. W. Gabrielsen1, J. U. Skaare3,4 1Norwegian Polar Institute, 9296 Tromsø, Norway 2Norwegian College of Fishery Science, University of Tromsø, 9037 Tromsø, Norway 3Norwegian School of Veterinary Science, PO Box 8146 Department, 0033 Oslo, Norway 4National Veterinary Institute, PO Box 8156 Department, 0033 Oslo, Norway *E-mail: katrine.borga@npolar.no ABSTRACT: Concentration and transport of organic pollutants by Arctic sea ice may expose iceassociated fauna to high contaminant concentrations relative to pelagic organisms. Zooplankton and ice-associated amphipods were collected in the marginal ice zone near Svalbard to investigate whether habitat, diet and geographic sampling site influenced their organochlorine burden. Organochlorine concentrations were low in both zooplankton (Calanus hyperboreus, Thysanoessa inermis, Parathemisto libellula, Chaetognatha) and ice-associated amphipods (Apherusa glacialis, Gammarus wilkitzkii, Onisimus spp.), from 0.3 ng g-1 lipid weight trans-chlordane in A. glacialis to 36.9 ng g-1 lipid weight hexachlorobenzene (HCB) in G. wilkitzkii. Diet accounted for most of the explained organochlorine variance, followed by habitat and geographic sampling site. The concentrations were higher in carnivores (P. libellula, Chaetognatha, G. wilkitzkii, Onisimus spp.) than in herbivores (C. hyperboreus, T. inermis, A. glacialis). In comparison with zooplankton, ice fauna had high levels of organochlorines with high residence time in surface layers (hexachlorocyclohexane [HCH] and HCB), whereas compounds with higher particle affinity did not differ between habitats. This was attributed to the sea ice serving as a habitat that keeps ice fauna in the surface layer, rather than to the release of contaminants from the sea ice itself. HCHs were the only compounds that differed geographically. Higher α / γ -HCH ratios in C. hyperboreus and A. glacialis from the Greenland Sea relative to North of Svalbard, are consistent with the geographic patterns in HCH levels reported for air, water, ringed seals Phoca hispida and polar bears Ursus maritimus. KEY WORDS: Zooplankton · Ice-associated · Svalbard · Greenland Sea · Crustaceans · Organochlorines · γ -HCH · α-HCH · Redundancy analysis Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 235. Online publication date: June 19, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.

Lipids and trophic interactions of ice fauna and pelagic zooplankton in the marginal ice zone of the Barents Sea

Gammarus wilkitzkii, Apherusa glacialis, Onismus nanseni, Onismus glacialis, Boreogadus saida, Parathemisto libellula and Calanus hyperboreus, collected in late June in the Barents Sea marginal ice zone, contained substantial levels (28–51% of the dry mass) of total lipid, the highest levels (51% and 41% respectively) being in A. glacialis and C. hyperboreus. Neutral lipids were present in greater amounts than polar lipids in all species. Triacylglycerols were major neutral lipids in A. glacialis, G. wilkitzkii and O. nanseni; triacylglycerols and wax esters were present in similar amounts in O. glacialis; higher levels of wax esters than triacylglycerols occurred in P. libellula; wax esters greatly exceeded triacylglycerols in C. hyperboreus, the opposite being true for B. saida. Diatom fatty acid markers were prominent in the triacylglycerols of G. wilkitzkii, O. nanseni, O. glacialis and, particularly, of A. glacialis; 20:1(n-9) and 22:1(n-11) moieties were abundant in wax esters of G. wilkitzkii, O. nanseni, O. glacialis, P. libellula and C. hyperboreus, and in triacylglycerols of B. saida. We deduce that A. glacialis feeds mainly on ice algae and phytodetritus, G. wilkitzkii and the Onismus spp. feed on calanoid copepods as well as ice algae, whereas P. libellula and especially B. saida feed extensively on calanoid copepods.

The ice fauna in the shallow southwestern Beaufort Sea, Arctic Ocean

Sympagic fauna were studied in seasonal fast ice adjacent to Narwhal Island during the spring of 1979 and 1980, with emphasis on the origin of the fauna and its relationship to contiguous pelagic and benthic communities. The results of five subprojects are reviewed and compared with recent literature. Within Stefansson Sound, inshore of Narwhal Island, total sympagic meiofaunal densities and species diversity were low. In March 1979, the dominant taxa were polychaete larvae and crustacean nauplii, while in May the dominant group was Nematoda. Total numerical densities were low, ranging from 4500 to 8000 per m 2. During the spring of 1980 large numbers of invertebrate fauna concentrated at the undersurface of seasonal sea ice on the inner western Beaufort Sea continental shelf, seaward of Narwhal Island. The sympagic meiofauna were comprised primarily of benthic harpacticoid and cyclopoid copepods, turbellarians, nematode worms, and polychaete worm larvae. Total meiofaunal densities increased from about 6000 per m 2 in April to about 482,000 per m 2 in June. All life stages of Cyclopina gracilis (Copepoda: Cyclopoida) were present in the ice. This species appeared to reproduce continuously from early April to early June during the study period. The Harpacticus sp. (Copepoda: Harpaticoida) population consisted of one cohort whose individuals grew in size from April to early June. The sympagic macrofauna consisted entirely of amphipod crustaceans, primarily comprised of benthic species. Population size structure of the amphipod Pseudalibrotus (= Onisimus) litoralis was bimodal and there was a lack of intermediate growth stages. These characteristics indicate that this species has a two-year life cycle in the Beaufort Sea. The highest growth rate for P. litoralis coincided with maximal ice algal production. P. litoralis fed largely on meiofaunal Crustacea and amphipod fragments in April, but its diet switched to ice algae during the height of the bloom in late May-early June. Results indicate that P. litoralis, normally a shallow benthic species, uses the ice undersurface as a spawning site and a temporary nursery ground for its young during the spring. Beneath the ice, the input of total organic carbon to the bottom remained at fairly constant low levels from April through early June, 1980. Little carbon, exported from the ice community beneath the sea ice, reached the shallow sea floor. However, this food source is available to the benthos earlier than that from phytoplanktonic or benthic microalgal production that occurs later in the season after ice breakup.

Sympagic macro-fauna from multiyear sea-ice near Svalbard

The object of the present investigation was to map the distribution and abundance of sympagic fauna (= ice fauna) (>350 μm) within the perennial sea ice zone near Svalbard and to study relations between the sympagic fauna and the age and history of its ice substrate. The sampling took place in July/August 1986 and September 1988 using SCUBA-operated sampling gear (suction samplers, plankton nets with especially designed frames for sampling at the sea-ice/seawater interface, and underwater cameras). The amphipods Apherusa glacialis, Onisimus sp., and Gammarus wilkitzkii were the most conspicuous sympagic species both years. Scattered individuals of the amphipods Gammaracanthus loricatus, Weyprechtia penguis and the polychaete Harmathoinae indet. were also recorded. A. glacialis was the most numerous and contributed near 65% of the collected specimens in both years, with a maximum density exceeding 2000 individuals/m2. However, G. wilkitzkii was on average larger, and contributed most to the biomass (1986: 80%; 1988: 77%). The average biomass of sympagic fauna in 1986 and 1988 was estimated to be 4.7 g/m2 and 8.3 g/m2 respectively. Biomass values reported here are ten to hundred times higher than what is found within the seasonal sea ice zone. Autochthonous sympagic species, like A. glacialis, Onisimus sp. and G. wilkitzkii, have a permanent association with ice. The seasonal sea ice zone will thus have to be recolonized every year resulting in lower densities compared to multiyear ice. It is suggested that the speed of the ice leaving the Polar Basin through the Fram Strait is too high for the sympagic fauna to remain its position in the sea ice zone. The result is an annual loss in the order of 7*105 tons of sympagic fauna from the perennial sea ice zone.

On the distribution of sympagic macro-fauna in the seasonally ice covered Barents Sea

The sympagic fauna (= sea ice fauna) of the Barents Sea was investigated on nine (2–5 weeks) cruises in the period 1983–1988. The amphipods Apherusa glacialis, Onisimus sp. and Gammarus wilkitzkii were the most conspicuous and abundant invertebrate species associated with the ice. Mean biomass-values ranged from 0 to about 2 g/m2, and were less than 0.001 g/m2 in five of the nine cruises. Apherusa glacialis, Onisimus sp. and Gammarus wilkitzkii are regarded as autochthonous sympagic species, and as such dependent upon a permanent ice cover. Allochthonous sympagic species were few and without significant importance. The variations in species abundance and biomass were believed to be closely connected to the age and drift-history of the ice. The density of the sympagic fauna increases as a result of increasing influx of ice into the Barents Sea from the Arctic Ocean. Density of the sympagic fauna were believed to increase with decreasing distance to the multiyear/first-year ice boundary. A. glacialis was found further away from the spreading centers and in higher numbers than the other sympagic species due to its greater motility. No day-night variations in the occurrences of the sympagic fauna were recorded.

Source, density and composition of sympagic fauna in the Barents Sea

The sympagic fauna (= ice fauna) of the Barents Sea was investigated on nine different cruises in 1982-1988. Each cruise lasted from two to five weeks. Sampling techniques were based on scuba diving. The abundant sympagic organisms were the polar cod (Boreogadus saida) and the three amphipods Apherusa glacialis, Onisimus sp. and Gammarus wilkitzkii. Mean biomass-values (wet weight) of the invertebrate sympagic fauna ranged from 0 to 2 g/m2. Values above 0.001 g/m2 were not recorded in five of the nine cruises. This is orders of magnitude lower than mean values recorded in multi-year ice north of Svalbard and in the Fram Strait where values between 1-10g/m2 are quite common. Apherusa glacialis seemed to have the best spreading capacity of the three most conspicuous amphipods. Gammarus wilkitzkii was most dependent on a passive transport with the ice. Sympagic amphipods play an important part in a food chain from microalgae to polar cod and marine birds in areas covered with ice, especially in areas with multi-year ice.

Trophic relationships of the sea ice meiofauna in Frobisher Bay, Arctic Canada

A distinct fauna consisting mainly of nematodes, harpacticoid and cyclopoid copepods, rotifers, turbellarians and polychaete larvae, inhabits the lower levels of the sea ice in Frobisher Bay. Similar faunas are found throughout circumpolar regions. Thirteen taxa of the Frobisher Bay ice fauna were entirely herbivorous. Their food consisted of 26 genera of algae dominated by Chlamydomonas, Nitzschia, Navicula and Chaetoceros. There was a clear tendency to feed on the most abundant ice algae, hence little evidence of selective feeding. High algal food concentrations in the ice (estimated at 5000 μg C/l) were in sharp contrast with the scant nourishment available from phytoplankton under the ice (8 μg C/l) from mid-winter until the start of the summer bloom. Algal stocks and estimated productivity rates indicate that ice meiofaunal food requirements may be met by the ice algae. All the major ice meiofaunal species are well adapted to feeding within the ice. All are small enough to enter brine channels and secure particulate prey from surfaces within confined spaces. The ice meiofaunal species are major consumers of the ice algae and therefore important links in the transfer of energy from the ice to pelagic and benthic predators, including fishes, birds and mammals.