Phytoplankton Composition and Geographical Distribution in the Eastern Laptev Sea in the Autumn 2008

• Main Author: Kryukova, Irina
• Format: Thesis
• Language: English
• Published: 2011
• Subjects: Arctic; Laptev Sea; Climate change; laptev; lena delta; Phytoplankton
• Online Access: https://oceanrep.geomar.de/id/eprint/28049/; https://oceanrep.geomar.de/id/eprint/28049/1/2011_Kryukova-Irina_MSc-Thesis.pdf

Over the last decades the Arctic region is experiencing an intense climate change leading to the variability of the marine environments in the Siberian shelf seas. The changes of the thermal conditions, ice cover, water masses circulation and other key parameters of marine environment directly affect the productivity of phytoplankton, its seasonal dynamics and peculiarities of species composition. Long-term observations of the phytoplankton assemblages in the high latitudes will provide the background for the assessment of ecosystem changes connected with climate variability in the Arctic region. This study is focused on the investigation of species composition and the peculiarities of spatial and temporal distribution of phytoplankton in the eastern Laptev Sea. Samples were collected during the TRANSDRIFT XIV expedition in September 2008. Phytoplankton abundances were determined by cell countings, which provided the basis for biomass calculations according to taxon-specific carbon values. The Shannon-Wiener index was used to estimate the species diversity. Special attention was paid to the ecological preferences and the phytogeographical distribution of identified species to reveal the influence of seasonal and abiotic factors (salinity, nutrient supply, riverine discharge etc.) on phytoplankton communities in the studied area. The obtained results indicated that we observed a late stage of a seasonal succession pattern of the phytoplankton community. The algal standing stock consisted mainly of marine planktonic diatoms and dinoflagellates. The overall abundance of algae in the water column ranged from 190 to 5 040 cell × l-1. Total phytoplankton biomass in the water column ranged between 0.15 and 9.65 μg C × l-1. The highest values of algal abundance and biomass were observed in the vicinity of the Lena Delta. Diatoms were dominated by arctic-boreal marine and brakish water-marine species (Thalassiosira baltica, T. hyperborea, Chaetoceros diadema, C. socialis, C. wighamii). Dinoflagellates of a wide ...