Exploitable results Biodiversity and adaptation strategies of Arctic coastal marine benthos Extreme low temperatures and absence of light over prolonged periods require in the Arctic unique adaptations of endemic organisms. Moreover, these organisms have to adapt nowadays to anthropogenic disturbances. Because human activities concentrate most where rivers meet the sea, the impact of changes in marine systems will be felt most strong by the benthic organisms that can not escape from natural and anthropogenic stress. Therefore, the INTAS study in the Arctic coastal area aimed at comparing and understanding 1) the present biodiversity of benthos in pristine and disturbed Arctic coastal ecosystems, and 2) the adaptive strategies of some Arctic benthic key species under natural and anthropogenic stress. In 1995 to 1998 four main expeditions to the White Sea, eastern Barents Sea and Pechora Sea were carried out to 1) determine the biodiversity through the benthic community composition, 2) to sample specimens of the key species, the bivalves Macoma balthica, the Baltic clam, and Mytilus edulis, the edible blue mussel, to assess their adaptive strategies and ecophysiological features, and 3) to make an inventory of the biogeochemical characteristics at the sampling stations to assess the (possible stress from) environmental conditions. Simultaneously, laboratory experiments and translocation experiments in the field were carried out to test the stress-sensitivity of the key-species and to possibly indicate the influence of natural and anthropogenic stress. Seven east and west European institutes participated in the project, and three Russian PhD students base their thesis on materials sampled during the INTAS missions. The estuaries could be divided geochemically in two different types: horizontally stratified and vertically stratified (well-mixed) estuaries. The horizontal stratification, controlled by a high river discharge, was most strong in the Dwina and Pechora estuaries. The Mezen, with a strong tidal amplitude, was the most well mixed estuary, where the most well mixed estuary, where the tides were more important than river discharge. The distribution of suspended matter (SPM), organic carbon (POC), chlorophyll and metals is determined by these major hydrological patterns. The different hydrodynamics determine salinity and grain size distribution, and are therefore forcing factors for benthos composition and biodiversity. Metals in the suspended matter in most estuaries could be divided in those from terrigenous origin (Al, Fe, Mn), showing decreasing concentrations from river mouth to open sea, and those controlled by mixing of marine material included in biological production processes (Cu, Zn), whereas the other metal (Cd, Pb, Co, Ni) showed an intermediate behaviour. In the sediments the metals are primarily minerally incorporated. Concentrations are strongly depended on grain size distribution and organic matter. The degree of heavy metal pollution is low, and only in organisms locally enhanced concentrations of metals were found (especially in Keret (Pb, Cu) and Khaypudyr (Pb, Cd). In general, contaminants do probably not reach levels influencing significantly the biota, and major part of the coastal area and estuaries may be judged to be pristine. The domination of a certain species in a faunal association of macrobenthos in dependent on the territory and hydrological conditions (primarily grain size and salinity). A major division could be made as follows: 1)White Sea versus Pechora Sea, 2) marine (above 25ppt), estuarine (around 15ppt) and brackish (around 2 ppt). Faunal associations with the bivalve Macoma balthica as the dominant species were typical in all inspected estuaries. Biomass was highest at mid-estuarine salinities, whereas the species diversity was higher with increasing salinity. No indications of anthropogenic stress were found. It was hypothesised that the performance (as growth or genetic diversity) of the key species (the clam Macoma balthica and the mussel Mytilus edulis) would decrease towards their northern limit of distribution in the eastern part of the Pechora Sea. In general, the performance (growth, glycogen level, genetic diversity) of both the key species in the White Sea was indeed slightly reduced in comparison to conspecifics from temperate areas (West and North Europe washed by the warm Gulfstream). Surprisingly, in the Pechora Sea the performance of the key species was often better than in other studied accomplished. Obviously, in the White Sea the acclimation of some ecophysiological factors to the sub-arctic conditions is not fully accomplished. Whereas in the Pechora Sea most probable genetic adaptation (as indicated by isoenzyme electrophoresis and foot colour morphs) due to differential selection (induced by the specific Arctic conditions of 8-month ice cover, short food season, and low temperatures) occurred, whereby the Arctic ecotypes (races or sub-species) are fully acclimatised. The genetic differentiation (whereby adapted races of marine invertebrates arose) may have been caused by hydrodynamic isolation barriers hindering gene flow, being in the White Sea the reduced hydrodynamics through Gorlo strait (a threshold in the northern entrance) and the freshwater outflow from the Dwina river, and in the Pechora Sea the on average 8 months coverage with ice. consequently, the subarctic White Sea and Arctic Perchora therefore harbour a fauna with unique races and species. Both key species from as well as the White Sea as the Pechora Sea showed a relatively (to temperate conspecifics) high stress resistance. the observed (physiological) acclimation and (genetic) adaptation processes, and the absence of major anthropogenic stressors, may be the cause for the absence of strong geographic differences in several ecophysiological factors of the key species, as oxygen consumption, reserve constituents (glycogen), free amino acids, antioxidant reactions, metallothionein levels. The values found can thus be used in monitoring programmes as baseline indicators for pristine areas. Searching for OpenAIRE data... There was an error trying to search data from OpenAIRE No results available
