Under-ice communities structured by sea-ice habitats in changing Arctic and Antarctic ecosystems

• Main Author: David, Carmen Lucia
• Other Authors: Brandt, Angelika (Prof. Dr.)
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Staats- und Universitätsbibliothek Hamburg Carl von Ossietzky 2015
• Subjects: 570 Biowissenschaften; Biologie; 42.07 Biogeographie; 42.65 Tiergeographie; Tierökologie; 42.94 Meeresbiologie; ddc:570; Arctic; Antarctic; Southern Ocean; Arctic Ocean; Weddell Sea; Weddell; Wandel; Antarc*; Antarktis*; Arktis; Arktis*; Climate change; Sea ice
• Online Access: http://nbn-resolving.de/urn:nbn:de:gbv:18-77962; https://ediss.sub.uni-hamburg.de/handle/ediss/6657

Over the past decades, the effects of global-climate change have been observed in the polar oceans. Our knowledge about how changes in sea-ice dynamics affect the associated fauna is limited, especially in the ice-covered central Arctic and the seasonal ice zone of the Southern Ocean. Ice-associated fauna is difficult to evaluate due to a lack of quantitative reports of species abundances and distribution. Moreover, understanding the factors that control ice-associated fauna distribution is crucial to predict how the ice-associated ecosystems in the polar oceans will react to further sea-ice decline. The overall aim of this thesis is to improve our understanding of the distribution and association of meso- and macrofauna communities with sea-ice habitat properties in central Arctic Ocean and northern Weddell Sea. Specific goals are to i) quantify the under-ice fauna distribution at large spatial scales, and identify under-ice community structures and their key species, ii) investigate how different community structures relate to environmental gradients and iii) analyse the relationships of the key species with environmental variables of the under-ice habitat. The innovative approach of this study is the use of the Surface and Under Ice Trawl (SUIT). The SUIT is equipped with an array of sensors to measure environmental parameters like sea-ice thickness and coverage, water temperature, salinity and chlorophyll a concentration; whilst collecting fauna. Chapter I and III address the first two goals by relating the under-ice faunal distribution with the variability of sea-ice and underlying water-column properties. Our results show that in summer, in the central Arctic Ocean, nutrient concentration, surface salinity and sea-ice coverage define two distinct environmental regimes (Chapter I). The under-ice community structure mirrors the environmental patterns at the basin scale. On small-scale patterns, abrupt changes in the dominance of ice-associated amphipods at ice-covered stations versus pelagic amphipods at ...