Structure of the zooplankton communities in the region of the Ob River’s estuarine frontal zone

Regional differences of mesozooplankton communities in the Kara Sea

“…In the examined samples, Copepoda made up the bulk of mesozooplankton in all of the regions delineated by cluster analysis, consistent with previous reports (Chislenko, 1972a(Chislenko, , 1972bFomin, 1989;Vinogradov et al, 1994aVinogradov et al, , 1994bFetzer et al, 2002;Hirche et al, 2006;Nesterova and Orlova, 2008;Flint et al, 2010). The small copepod O. similis together with Pseudocalanus species were found in high densities in all the samples; this was expected since these taxa can be considered as most numerous copepods in the western Arctic region (Barents, White, and Kara seas; Dvoretsky and Dvoretsky, 2011a).…”

“…It is connected with the major currents and heat transport from adjacent areas (Hirche et al, 2006). In the shallow regions (central part of the Kara Sea and ObYenisei area), we recorded a halocline at 5-10 m. Similar hydrographic profiles have been previously recorded in the southern Kara Sea (Fetzer et al, 2002;Flint et al, 2010), Hudson Bay (Roff and Legendre, 1986), the south-eastern Barents Sea (Dvoretsky and Dvoretsky, 2009d), and the Laptev Sea (Schmid et al, 2006). The main factor determining a sharp vertical salinity gradient is freshwater discharge.…”

“…Knowledge of the zooplankton community patterns in the Kara Sea is still very limited despite recent advances in the study of pelagic ecosystems in this hard-to-access, high-Arctic region (Hirche et al, 2006;Flint et al, 2010). In our study we investigated mesozooplankton communities in all regions of the Kara Sea except for eastern area.…”

“…Total zooplankton biomass in the southern Kara Sea fluctuates in a wide range ( Table 6). The highest biomass has been recorded by Flint et al (2010) in September 2007. Such high biomass was associated with a frontal zone in the Ob Estuary where there was a mixing of fresh and marine waters.…”

“…They were focused on different regions -southern (Fetzer et al, 2002;Flint et al, 2010), south-eastern (Chislenko 1972a(Chislenko , 1972bVinogradov et al, 1994a), south-western (Fomin, 1989;Vinogradov et al, 1994b;Nesterova and Orlova 2008), and north-western (Nesterova and Orlova, 2008). The western area (Novaya Zemlya Trough area) has not been studied at all.…”