Polar Biology 

About: Polar Biology is an academic journal published by Springer Science+Business Media. The journal publishes majorly in the area(s): Population & Arctic. It has an ISSN identifier of 0722-4060. Over the lifetime, 5034 publications have been published receiving 141317 citations.

Ecology of sea ice biota 2. Global significance.

Abstract: 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 CO2 before 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.

The nature of the diversity of Antarctic fishes

Abstract: The species diversity of the Antarctic fish fauna changed notably during the ≈40 million years from the Eocene to the present. A taxonomically restricted and endemic modern fauna succeeded a taxonomically diverse and cosmopolitan Eocene fauna. Although the Southern Ocean is 10% of the world’s ocean, its current fish fauna consists of only 322 species, small considering the global diversity of ≈25,000–28,000 species. The fauna is “reasonably well-known” from a taxonomic perspective. This intermediate designation between “poorly known” and “well-known” indicates that new species are regularly being described. A conservative estimate of the number of undescribed species is ≈30–60; many of these may be liparids. On the Antarctic continental shelf and upper slope the fauna includes 222 species from 19 families of benthic fishes. The most speciose taxa are notothenioids, liparids and zoarcids, accounting for 88% of species diversity. Endemism for Antarctic species is also, coincidentally, 88%, at least threefold higher than in faunas from other isolated marine localities. Eight notothenioid families, including five that are primarily Antarctic, encompass a total of 44 genera and 129 species, 101 Antarctic and 28 non-Antarctic. The 101 Antarctic species make up 45% of the benthic species diversity in the Antarctic region. However, at the highest latitudes, notothenioids contribute 77% of the species diversity, 92% of the abundance and 91% of the biomass. Although species diversity is low compared to other shelf habitats, the nature of the adaptive radiation in organismal diversity among notothenioids is noteworthy in the marine realm. In some notothenioid clades phyletic diversification was accompanied by considerable morphological and ecological diversification. The exemplar is the benthic family Nototheniidae that underwent a habitat or depth related diversification centred on the alteration of buoyancy. They occupy an array of pelagic and benthopelagic habitats at various depths on the shelf and upper slope. Diversification in buoyancy is the hallmark of the nototheniid radiation and, in the absence of swim bladders, was accomplished by a combination of reduced skeletal mineralisation and lipid deposition. Although neutral buoyancy is found in only five species of nototheniids some, like Pleuragramma antarcticum, are abundant and ecologically important. Much work remains to be done in order to frame and to use phylogenetically based statistical methods to test hypotheses relating to the key features of the notothenioid radiation. To reach this analytical phase more completely resolved cladograms that include phyletically basal and non-Antarctic species are essential.

Dynamics of nutrients and phytoplankton, and fluxes of carbon, nitrogen and silicon in the Antarctic Ocean

Abstract: Four major functional units have been identified in the Southern Ocean and the mechanisms that control the dynamics of nutrients and phytoplankton are detailed for the different sub-systems. The very productive Coastal and Continental Shelf Zone (CCSZ, 0.9 M km 2) can experience severe macronutrient depletion paralleling intense diatom-dominated phytoplankton blooming (maximum > 8 mg Chl a m−3) at the ice edge. In the Seasonal Ice Zone (SIZ, 16 M km 2) dramatic variations in the hydrological structure occur in surface waters during the spring to summer retreat of the pack-ice, changing from a well-mixed system to a stratified one within the reaches of the ice edge. Grazing activity of euphausiids limits phytoplankton biomass to a moderate level (Chl a maximum around 4mg m−3). A shift from new production to a regenerated production regime has been demonstrated during spring, along with the key role played by protozoans in controlling high ammonium concentrations (maximum > 2 μM) in the surface layers. The well-mixed Permanently Open Ocean Zone (POOZ, 14 M km 2) is characterised by variable N/Si ratios in surface waters along a north-south transect: at the northern border of the POOZ (N/Si = 0.25) silicate concentrations as low as <10 μM could help limit the phytoplankton growth. Although favourable conditions have been demonstrated for the initiation of blooms in spring in the Antarctic Circumpolar Current, it appears that critical-depth/ mixing-depth relationships control maximum chlorophyll a concentrations < 1 μg l−1 during summer. The POOZ is usually not influenced directly by euphausiids, except for the Scotia Sea and Drake Passage where migrations of krill from the adjacent SIZ are usual. Mesoscale eddies are typical of the Polar Front Zone (FPZ, 3 M km 2): significant increases in phytoplankton biomass have been reported in this frontal area (maximum Chl a = 2 mg m−3). Food web and biogeochemical cycles in this sub-system are poorly documented. The question of limitation of the primary production by eolian-transported trace-metals in these different sub-systems is still a matter of debate, although clear iron limitation has been evidenced for offshore waters of the Ross Sea.

Increases in Antarctic penguin populations: reduced competition with whales or a loss of sea ice due to environmental warming?

Abstract: A central tenet of Antarctic ecology suggests that increases in Chinstrap Penguin (Pygoscelis antarctica) populations during the last four decades resulted from an increase in prey availability brought on by the decrease in baleen whale stocks. We question this tenet and present evidence to support the hypothesis that these increases are due to a gradual decrease in the frequency of cold years with extensive winter sea ice cover resulting from environmental warming. Supporting data were derived from one of the first, major multidisciplinary winter expedition to the Scotia and Weddell seas; recent satellite images of ocean ice cover; and the analysis of long-term surface temperature records and penguin demography. Our observations indicate there is a need to pay close attention to environmental data in the management of Southern Ocean resources given the complexity of relating biological changes to ecological perturbations.

On the direct impact of ice on marine benthic communities, a review

Abstract: Ice has a significant impact on the polar and sub-polar benthos, but relationships between corresponding physical and biological processes are not yet sufficiently understood. Sea ice contributes to a vertical zonation in shallow waters, which also experience other important disturbances. Due to the length of the non-glaciated coastline, sea ice is of greater relevance in the north than in the south. Scouring by icebergs and ridged sea ice causes an increased diversity when different recolonisation stages coexist. Frequently scoured areas do not recover, especially in the Antarctic, due to slow growth rates of the fauna. Iceberg grounding in the Arctic is mainly restricted to the western Eurasian and northeastern American shelf, including Greenland. Around Antarctica, scouring is more evenly distributed. Glacier termini prevent sessile animals from settling in their proximity where only few motile species occur.