A Molecular Assessment of the Diversity andBiogeographicalDistribution of Eukaryotic Protists in the Arctic Ocean

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(1)Abstract number 0269. A Molecular Assessment of the Diversity and Biogeographical Distribution of Eukaryotic Protists in the Arctic Ocean Estelle. 1 Kilias ,. Eduard. 1Alfred-Wegener-Institute. 1 Bauerfeind ,. Eva-Maria. 1 Nöthig ,. Christian. 1 Wolf ,. Katja. 1 Metfies. for Polar and Marine Science, Am Handelshafen 12, 27570 Bremerhaven, Germany. Objective The aim of this study is the assessment of the diversity and distribution of eukaryotic protists in the Arctic Ocean, with special emphasis on the picoplankton fraction. In order to elucidate the impact of changing conditions on the picoplankton community in the Arctic Ocean the results will be compared with regard to abiotic factors.. Introduction It is expected that the progressing environmental change, reflected by increasing air temperatures and radiation, or a decreasing sea ice cover will strongly impact Arctic marine ecosystems. This requires an evaluation of the impact on local phytoplankton communities, who are transforming CO2 in biomass and display therefore a major part of primary producers. Important premises of such an evaluation are comprehensive information on the present phytoplankton diversity, distribution and variability. Recent investigations indicate that rising temperatures in the marine environment promote a shift in the phytoplankton community towards small cells (e.g. picoplankton). Considering the increasing importance of picoplankton in marine ecosystems, we are currently assessing the picoplankton community in samples taken in 2009 in the “AWI-Hausgarten”(Fram Strait) during the RV Polarstern expedition ARK XXIV/2 by the application of 18S rDNA clone libraries, 454-sequencing and ribosomal fingerprints.. HG 116 HG 109. HG 104. HG 129. Map of the investigation area: “AWI-Hausgarten” (Fram Strait). Results Ark108. HG 129, 30m. HG 129, 30m. HG 104, 25m. HG 109, 15m. Ark 108 70m. Clone library. Ark219. Ark 219 80m. HG 116, 40m. HG 104, 25m. HG 116, 40m. HG 109, 15m. northern & southern stations show a variety of operational taxonomic units (OTUs) while the western and eastern stations are less variable & dominated by one pattern. Ark120. Ark 120 10m. Ark228 Ark 228. Ark216 Ark 216 100m. Ark222. Ark 222 50m. ARISA Fingerprint North/South Transect. West/East Transect. Temperature and Salinity profile of the north-south and west-east transect. HG 104. HG 116. HG 109. HG 129. A dendrogram reveals two major branches One major branch is constituted by taxons from the HG 116 & HG 129 stations and the second branch is constituted by HG 104 & HG 109 stations conspicuous resemblance in the composition of the deeper water layer taxons from HG 129 & the upper layer from HG 116 same similarity between deeper water layer taxons of station HG 109 & upper of HG 104. 30m. Ark111 Ark 111. 40m. Ark225 Ark 225. 40m. Ark114 Ark 114. 30m. Ark117 Ark 117. 20m. Ark81 Ark. 81 35m. Ark231. Ark 231 20m. HG 116 North. Ark12. Ark 12 50m. HG 104 West. Ark9 Ark. 09 25m. Ark72 Ark. 72 75m. Ark78 Ark. 78 40m. HG 109 East HG 129 South 0.1. RFLP band pattern from the clone libraries (200 colonies per library). Dendrogram from the ARISA (automated ribosomal intergenic spacer analysis) Fingerprint. Conclusion & Outlook The dendrogram indicates two main branches. One containing the stations HG 129 and HG 116 and the other comprising HG 104 and HG 109. This observation points to a higher similarity of the northern/southern stations and accordingly the eastern/western stations. By taking the depth into account the upper layer of station HG 116 resemble the deeper water layer of HG 129. Similarly it can be observed for the second branch that the upper layer of HG 104 is similar to HG 109. This observation could be explained by a phytoplankton bloom situation versus post bloom situation. At station HG 109 and HG 129 the bloom is already descended to deeper layers. This is in agreement with the local ice coverage which could only be found in slight dimensions at station HG 104 and HG 116. The results from the clone libraries support these assumption. Here the northern (HG 116)/ southern (HG 129) stations display a high similar degree of diversity. In contrast, the western (HG 104)/ eastern (HG 109) stations demonstrate a roughly uniform diversity. • To attain a better insight in the spatial distribution of picoeukaryote diversity in the “Hausgarten” further environmental samples from ArkXXIV/2 (2009) will be analyzed • Additionally a third method (454-sequencing) of the 18S rDNA V4-Region will provide a high resolution picture of the picoeukaryote community structure & OTUs that differ in pattern will be sequenced to get a more precise approach of the diversity • Future expeditions will take additional samples consisting the four “Hausgarten” stations to assess annual variability (2010-2012). Estelle.Kilias@awi.de.

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