Поиск по автору "Strelkova, N. A."
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Материал Barents Sea megabenthos: Spatial and temporal distribution and production(2020) Zakharov, D. V.; Jørgensen, L. L.; Manushin, I. E.; Strelkova, N. A.This long-term observation of the faunal composition within the Barents Sea provides a benchmark for monitoring community changes caused by oceanographic variability, fishery activities, and crab predators (Chionoecetes opilio, Paralithodes camtschaticus), whose populations have been rapidly growing and spreading in recent years. In the Arctic systems, megabenthic communities comprise a significant part of benthic biomass and play an important role in carbon cycling on continental shelves. The gradual accumulation of knowledge on megabenthos may make it possible to assess their role in the ecosystem and ultimately contribute to a more rational management of the Barents Sea resources. This article represents an important series of long-term megabenthic observations in the Barents Sea. The main goal of our research is to identify spatial patterns and temporal trends in the megabenthic part of communities, including changes in the biomass and production values. As a part of the joint Norwegian-Russian ecosystem surveys, benthic experts have been identifying the invertebrates (megafauna) collected by bottom trawls during annual assessments of commercial stocks, such as Atlantic cod (Gadus morhua) and northern shrimp (Pandalus borealis). The sampling equipment used was a Campelen 1800 bottom trawl, rigged with rockhopper ground gear and towed on double warps, and standardized to a fixed sampling effort (equivalent to a towing distance of 0.75 nautical miles (nm), or 1.4 km). The processing of the biological material was conducted in accordance with standardized procedures, following the retrieval of each trawl. This work represents data from 5016 stations from 2005 to 2017, with a total sampled biomass of 238.4 tons and 14.9 million individual organisms. In total, 694 megabenthic species (1058 taxa) have been recorded, with the greatest diversity observed in the depth range of 100–400 m, while the largest mean catches were taken between depths of 600–800 m. The biomass (B) and production (P) values of the benthic megafauna were approximately stable during the 9 years of investigation, although there was a decreasing trend after 2014. The annual production P/B ratio of megabenthos was calculated to be at 0.3. The distribution, contribution to production, and gross biomass values of the megabenthos had been underestimated in the previous studies of zoobenthos. The results from this research show that, in the current warm period, the majority of the Barents Sea is in an intermediate state between the Arctic and boreal regions due to the wide distribution of boreal species toward the north. The dynamics of the mean biogeographical index (the border between areas of the dominance of boreal and Arctic species) within the central-southern part of the Barents Sea suggests that a large part of the area can be characterized as predominantly boreal intermediate since 2013.Материал Species composition and biogeographic structure of the polychaete fauna of the Pechora Sea during warming in the Arctic(2022) Gagaev, S. Yu.; Denisenko, S. G.; Strelkova, N. A.; Frolova, E. A.; Sikorski, A. V.A comprehensive study of benthos allows not only to see the current changes in benthic communities and better understand what happened to them in the past, but also to predict their future with a certain degree of reliability. Polychaete worms are one of the most numerous and significant groups of benthos, and those can serve as bioindicators of the state of the environment. This article attempts to analyze changes in the biogeographic groups of polychaetes in the Pechora Sea over a relatively long time period (~ 50 years) in order to understand whether the climate change affects the ratio of these groups and, consequently, whether polychaetes can serve as bioindicators to a certain degree. Based on the analysis of new data and material obtained earlier, a general list of polychaete worms of the Pechora Sea was formed. The list includes 198 taxa (out of them, 186 are identified down to a species level) belonging to 127 genera, 37 families, and 15 orders. The ratio of biogeographic groups of polychaetes in the Pechora Sea indicates the consistency of their biogeographic structure over the past 50 years and confirms the cyclicity of processes occurring in the Arctic.