Community structure of amphipods from sediment traps in the eastern Fram Strait - interactions with environmental parameters in a changing Arctic. Eberhard Karls University Tübingen

• Main Author: Schröter, Franz
• Format: Thesis
• Language: unknown
• Published: 2016
• Subjects: Arctic; Fram Strait; North Atlantic; North Atlantic oscillation; Sea ice; Themisto; Zooplankton; Copepods
• Online Access: https://epic.awi.de/id/eprint/42335/; https://hdl.handle.net/10013/epic.49668

Summary: During the last twenty years, the Arctic is under rapid environmental change also affecting the marine fauna. In this context, samples from sediment traps (200m water depth) of the Long-Term Ecological Research (LTER) observatory HAUSGARTEN in the northeastern Fram Strait (79°N, 4°E) have been used to obtain year-round abundances and inter-annual trends of zooplankton swimmers in time-series from the year 2000 until 2014. Those time-series sediment trap samples offer a unique insight into Arctic zooplankton population dynamics and changes therein. Dominating swimmer biomass, Arctic pelagic amphipods represent a valuable data source to reveal environmental changes. Amphipods are key species in the Arctic pelagic system linking primary consumers such as copepods with higher trophic levels like marine mammals and sea birds. This investigation is mainly based on amphipod sampling data of three consecutive years (2011-2014) obtained at two locations within the LTER HAUSGARTEN. In total, seven amphipod species of four taxonomic families could be observed (Hyperiidae, Lanceolidae, Eusiridae, and Gammaridae). Amphipods of the genus Themisto could be shown to dominate the epipelagic amphipod community by >97%. The latest abundance development of the native Themisto species – the boreal T. abyssorum and the Arctic T. libellula – and the intruding T. compressa is described and related to environmental data such as sea ice extend, North Atlantic Oscillation index, marine current velocity, current direction, ocean temperature, and water salinity. Between 2000 and 2014, increasing amphipod abundances could be observed, presumably due to changed trophic interactions and the warming system. Abundances analyzed at the central HAUSGARTEN site were considerably larger than at the northern location, which was likely provoked by hydrographic features and differences in sea ice cover. Further, range shifts in amphipods are evident: abundances of the North Atlantic species T. compressa continued to increase compared to ...