Assessment of exposure of benthic organisms to selected organochlorine pollutants in the west Spitsbergen fjords.

Climate-related changes in environmental conditions, such as reduction of sea ice, intensive glacier retreat, and increasing summer precipitation, directly influence the arctic marine environment and, therefore, the organisms living there. Benthic organisms, being an important food source for organisms from higher trophic levels, constitute an important part of the Arctic trophic network. Moreover, the long lifespan and limited mobility of some benthic species make them suitable for the study of the spatial and temporal variability of contaminants. In this study, organochlorine pollutants (polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB)) were measured in benthic organisms collected in three fjords of western Spitsbergen. Two of these were recommended by the Marine Biodiversity and Ecosystem Functioning (MARBEF) Network of Excellence as European flagship sites, namely Hornsund as the Biodiversity Inventory and Kongsfjorden as the Long-Term Biodiversity Observatory. Adventfjorden, with notable human activity, was also studied. Æ©7 PCB and HCB concentrations in sediments were up to 2.4 and 0.18 ng/g d.w. respectively. Concentrations of Æ©7 PCBs and HCB measured in collected benthic organisms were up to 9.1 and 13 ng/g w.w., respectively. In several samples (41 of 169) the concentrations of ∑7 PCBs were below the detection limit values, yet nevertheless the results of the research show effective accumulation of target organochlorine contaminants by many Arctic benthic organisms. Important interspecies differences were observed. Free-living, mobile taxa, such as shrimp Eualus gaimardii, have accumulated a large quantity of contaminants, most probably due to their predatory lifestyle. ∑7 PCB and HCB concentrations were both significantly higher in Hornsund than in Kongsfjorden. Biomagnification occurred in 0 to 100 % of the predator-prey pairs, depending on the congener analyzed. Although the sampled organisms were proved to have accumulated organochlorine contaminants, the measured levels can be considered low, and not posing a substantial threat to the biota.

Will shrinking body size and increasing species diversity of crustaceans follow the warming of the Arctic littoral?

Over thirty species of littoral marine Gammaridea occur along the coasts of the North Atlantic. From one to several species can coexist in a single region. There is an evident, inverse relationship between egg incubation time and temperature (from 14 to >120 days) and consequent trends in the size of the animals on reaching maturity (from 5 mm in warmer waters to 30 mm in the coldest ones) and in lifespan (from <6 months to >5 years). Littoral gammarids are a good example of the shrinking size effect of increasing temperatures and size-related species diversity. In large species, the annual cohorts of the population (3-5 annual size groups) functionally replace the adults of smaller species. The ongoing warming of the European Arctic seas may extend the distribution limits of boreal species so that more Gammarus species may appear on northern coasts hitherto occupied by just one or at most two species.

Range extension of a boreal amphipod Gammarus oceanicus in the warming Arctic.

The recent (2008-2016) occurrence of a boreal intertidal amphipod Gammarus oceanicus along the Spitsbergen coast is compared with corresponding data from 1980 to 1994. We aimed to compare the pace of environmental changes in the area (ice retreat, temperature increase) with distribution change of G. oceanicus. Material for the study was collected from intertidal, at low water level from over 100 locations on Spitsbergen, the main island of Svalbard archipelago (expanding from 76 to 80°N). The west coast of the island has been exposed to a steady increase in sea surface and air temperature (2°C in 20 years), as well as a significant decrease in fast ice duration (from over 5 months to less than 1 per year). A total length of more than 3,600 km of the island's coastline has been recently impacted by warming. Of the two sibling Gammarus species that dwell in the Spitsbergen littoral, G. setosus, the local cold water species remains generally where it was observed about 20-30 years ago. By contrast, boreal G. oceanicus has expanded its distribution range by over 1,300 km along the west and north coasts of Spitsbergen and gained dominating position on the number of sites, where it was previously just an occasional species.

Unexpected Levels of Biological Activity during the Polar Night Offer New Perspectives on a Warming Arctic.

The current understanding of Arctic ecosystems is deeply rooted in the classical view of a bottom-up controlled system with strong physical forcing and seasonality in primary-production regimes. Consequently, the Arctic polar night is commonly disregarded as a time of year when biological activities are reduced to a minimum due to a reduced food supply. Here, based upon a multidisciplinary ecosystem-scale study from the polar night at 79°N, we present an entirely different view. Instead of an ecosystem that has entered a resting state, we document a system with high activity levels and biological interactions across most trophic levels. In some habitats, biological diversity and presence of juvenile stages were elevated in winter months compared to the more productive and sunlit periods. Ultimately, our results suggest a different perspective regarding ecosystem function that will be of importance for future environmental management and decision making, especially at a time when Arctic regions are experiencing accelerated environmental change [1].