부산대학교 도서관

In the Arctic Ocean, sea-ice decline will significantly change the structure of biological communities. At the same time, changing nutrient dynamics can have similarly strong and potentially interacting effects. To investigate the response of the taxonomic and trophic structure of planktonic and ice-associated communities to varying sea-ice properties and nutrient concentrations, we analysed four different communities sampled in the Eurasian Basin in summer 2012: (1) protists and (2) metazoans from the under-ice habitat, and (3) protists and (4) metazoans from the epipelagic habitat. The taxonomic composition of protist communities was characterised with 18S meta-barcoding. The taxonomic composition of metazoan communities was determined based on morphology. The analysis of environmental parameters identified (i) a 'shelf-influenced' regime with melting sea ice, high-silicate concentrations and low NO.sub.x (nitrate + nitrite) concentrations; (ii) a 'Polar' regime with low silicate concentrations and low NO.sub.x concentrations; and (iii) an 'Atlantic' regime with low silicate concentrations and high NO.sub.x concentrations. Multivariate analyses of combined bio-environmental datasets showed that taxonomic community structure primarily responded to the variability of sea-ice properties and hydrography across all four communities. Trophic community structure, however, responded significantly to NO.sub.x concentrations. In three of the four communities, the most heterotrophic trophic group significantly dominated in the NO.sub.x-poor shelf-influenced and Polar regimes compared to the NO.sub.x-rich Atlantic regime. The more heterotrophic, NO.sub.x-poor regimes were associated with lower productivity and carbon export than the NO.sub.x-rich Atlantic regime. For modelling future Arctic ecosystems, it is important to consider that taxonomic diversity can respond to different drivers than trophic diversity.
Author(s): Hauke Flores [sup.1] [sup.2], Carmen David [sup.1] [sup.2] [sup.3], Julia Ehrlich [sup.1] [sup.2], Kristin Hardge [sup.1], Doreen Kohlbach [sup.1] [sup.2], Benjamin A. Lange [sup.1] [sup.2] [sup.4], Barbara Niehoff [sup.1], [...]