Abstract
Information about invertebrates in the low-flow water bodies of northeastern Siberia is far from complete. In particular, little is known about crustaceans—one of the main components of meiobenthic and zooplanktonic communities. An open question is which environmental factors significantly affect the crustaceans in different taxonomic and ecological groups? Based on the data collected on the zooplankton and meiobenthos in the tundra ponds in the southern part of the Lena River Delta, analysis of the crustacean taxocene structure was performed. In total, 59 crustacean species and taxa were found. Five of these are new for the region. The species richness was higher in the large thermokarst lakes than in the small water bodies, and the abundance was higher in small polygonal ponds than in the other water bodies. Variations in the Cladocera assemblages were mainly affected by the annual differences in the water temperature; non-harpacticoid copepods were generally determined by hydrochemical factors; and for Harpacticoida, the macrophyte composition was significant. Three types of the crustacean assemblages characteristic of different stages of tundra lake development were distinguished. The hypothesis that the formation of crustacean taxocenes in the Lena River Delta is mainly determined by two types of ecological filters, temperature and local features of the water body, was confirmed.
Highlights
The Lena River Delta, which has an area of approximately 30,000 km2, is the largest delta in the Arctic and third largest in the world after the Amazon and Ganges deltas [1].In its territory, dissected by numerous channels, there are more than 30 thousand lakes, polygonal, thermocarst or oxbow in origin, most of which are small.Fluvial river sediments in the delta formed river terraces enclosing three levels in theLate Pleistocene and during the Holocene [2]
The first data collected on freshwater crustaceans of the Lena River Delta were obtained during the Russian Polar Expedition of 1901–1903 and presented by Rylov [4] and Behning [5]
Fifty-nine crustacean species and taxa were identified: 39 copepod species, 18 branchiopod species (13 genera), one Amphipoda species and no identified Ostracoda (Table 1). Five of these crustaceans had not previously been recorded from the Lena River Delta and neighbouring territories of NW Siberia, they are quite widespread through the northern Palaearctic: two cladocerans (Alona quadrangularis (Müller O.F., 1776) and Paralona pigra Sars G.O., 1862) and three harpacticoids
Summary
The Lena River Delta, which has an area of approximately 30,000 km , is the largest delta in the Arctic and third largest in the world after the Amazon and Ganges deltas [1].In its territory, dissected by numerous channels, there are more than 30 thousand lakes, polygonal, thermocarst or oxbow in origin, most of which are small (less than 0.25 km2 ).Fluvial river sediments in the delta formed river terraces enclosing three levels in theLate Pleistocene and during the Holocene [2]. The different geneses, deposit types, and relief-forming processes of these geomorphological terraces caused the differences in their predominant lake types [3]. The first data collected on freshwater crustaceans (primarily Cladocera and Copepoda) of the Lena River Delta were obtained during the Russian Polar Expedition of 1901–1903 and presented by Rylov [4] and Behning [5]. Based on these data, a general list of fauna, including approximately 50 species and forms, was compiled. While analysing materials collected in the Lena River and delta channels, as well as in Tiksi, Oleneksky and Neelova bays, a more complete list of planktonic organisms was compiled, merging
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