Nature Conservation Research: Заповедная наука (Aug 2020)
Crustaceans of Wrangel Island (Russia): species composition, community structure and variability
Abstract
High-latitude aquatic ecosystems and the communities inhabiting them are the key sites for environmental research and observations of global climate changes. Due to their specific traits, they are highly sensitive to any external effects and respond immediately to stressors. Monitoring the state of communities of invertebrates of such water bodies is one of the most relevant areas of Arctic research. Wrangel Island is a unique natural area that combines high-latitudinal conditions, endemism and specificity of insular fauna, as well as local features of its biogeographic position in the zone of interaction of Palearctic and Nearctic biota. This kind of research is an integral part of the investigations carried out on the island. However, the composition of the aquatic invertebrates of the island is very poorly studied. The current paper presents new data on the crustaceans of inland water bodies of the Wrangel Island State Nature Reserve (Chukotka, Russia). There are 17 species previously unknown for this territory. Analysis of the influence of environmental factors on the community structure of crustaceans has revealed the most important of them: the type of bottom sediment, size of the water bodies, the area of research and seasonality. Lakes with an area of more than 100 m2 and with a silt or clay bottom were dominated by large (more than 0.7 mm) Copepoda of the order Calanoida: Diaptomus, Arctodiaptomus, Leptodiaptomus, Heterocope, Eurytemora, and Cladocera: Daphnia cf. middendorfiana. In thermocarst lakes, rich in detritus with size less than 50 m2, were abundant small (less than 0.5 mm) members of Copepoda orders Cyclopoida and Harpacticoida. The seasonal variability of the zooplankton community structure was clearly expressed. During spring a complex of bento-plankton species with a minimal number of species was prevalent (at average 5 species). At the end of June, the juvenile stages of the copepods dominate, cladocerans appear, and the total species richness increased 4 times (20-24 species). In the middle of the summer in all water bodies there were numerous adult copepods and cladocerans. By the beginning of August, the diversity and abundance of copepods began to decline, against the background of the unchanged composition of mass species of Cladocera. Two main types of communities are allocated that maintain an interannual stability. The first one is dominated by Calanoida and branchiopods, the second one by representatives of Daphnia and Chydorus. It is noted that although the genera composition of crustaceans in water bodies hardly changes from year to year, the composition of species has been subject to significant variability. It is shown that the structure of zooplankton communities in Arctic water bodies is primarily determined by two types of environmental filters: local, related to the specificity of the water body due to the history of its formation, and seasonality.
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