idw – Informationsdienst Wissenschaft
Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
idw - Informationsdienst
Wissenschaft
06/22/2016 - 06/22/2016 | Bremerhaven
Referentin: Dr. Ekaterina Abramova, Lena-Delta Nature Reserve, Tiksi, Sakha Republic, Russia
The information concerning pelagic fauna of the lakes and rivers in the Russian Arctic areas is still deficient and Lena River Delta, one of the biggest deltas in the World, is not an exception. Investigations over a fifteen year period (2000-2015) have resulted in the determination of 126 zooplankton taxa belonging to Rotifera and Arthropoda phyla in oxbow lakes, thermokarst lakes, polygon ponds, and floodplain waterbodies in the southern part of the Lena River Delta. Six Copepoda and seven Cladocera species were recorded for the first time in the Lena Delta region. Three calanoid copepods, Eurytemora arctica, E. foveola and Limnocalanus johanseni, are new species to Eurasian pelagic fauna, previously known only from Alaska and Canada.
Clear differences were noted between the zooplankton communities in the various waterbodies. The data obtained demonstrate a rather high zooplankton diversity, abundance and biomass in tundra waters, despite the short ice-free season. Analysis of life cycles revealed a high level of adaptation of zooplankton organisms to the severe environmental conditions through marked synchronization in the development of common species populations. The pelagic fauna of the investigated waterbodies in the Lena Delta is heterogeneous in its origin and consists mainly of aboriginal Arctic species, together with representatives of relict ice-age fauna and invasive species from more temperate parts of the Lena River catchment area. We suggest that the presence of some crustaceans in the Lena Delta pelagic fauna may relate to the strong effects that the last glaciation had on crustacean biogeography in circumpolar regions.
Our results indicate the close interaction of the coupled Laptev Sea- Lena Delta system. Freshwater organisms brought by the river runoff constitute about 50% of the summer total zooplankton abundance in the shallow brackish water bays of the Laptev Sea. The distribution pattern and seasonal-interannual variations of zooplankton species composition, abundance and biomass, depending on primary production, hydrological, hydrochemical and ice conditions were analyzed for the Laptev Sea shelf. The data were collected during summer and winter Russian-German TRANSDRIFT IV-XXII expeditions (1996-2014). A total number of 111 taxa from 10 phyla were found on the Laptev Sea shelf. Sixteen species are reported from this region for the first time. The distribution and abundance of zooplankton on the Laptev Sea shelf is dependent on the main direction of river water spread, which varies between years. While the western and northeastern Laptev Sea shelf is dominated by a marine– neritic fauna, the central part is inhabited by a transitional brackish–marine assemblage. A brackish–neritic community characterizes the eastern and southeastern regions, where lowest salinities usually prevail. Several target small brackishwater copepods: Drepanopus bungei, Acartia longiremis, Pseudocalanus spp. and marine everyhaline Oithona similis, Microcalanus pygmaeus, Onceae borealis initially were selected as the focus of extensive study because of their numeric importance and their ubiquitous distribution on the Laptev Sea shelf in different seasons of the year. During the last ten yeas O. similis prevailed numerically almost over the whole Laptev See shelf. This species was found at nearly all sampled depths and locations with greatest number (up to 70% of the total zooplankton abundance). In opposite, the share of D. bungei, previously dominated in the eastern Laptev Sea, dramatically reduced up to 2% of the total zooplankton abundance.
Pelagic species diversity and distribution are important measures of environmental change in the Arctic, and may serve as ‘rapid-responders’ to climate-induced changes in this fragile arctic ecosystem.
Information on participating / attending:
Date:
06/22/2016 14:00 - 06/22/2016
Event venue:
Alfred-Wegener-Institut, Hörsaal, Columbusstraße / Am Alten Hafen 26
27568 Bremerhaven
Bremen
Germany
Target group:
Scientists and scholars, Students
Relevance:
regional
Subject areas:
Biology, Oceanology / climate
Types of events:
Presentation / colloquium / lecture
Entry:
04/07/2016
Sender/author:
Ralf Röchert
Department:
Kommunikation und Medien
Event is free:
yes
Language of the text:
German
URL of this event: http://idw-online.de/en/event53922
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