Comparisons of megafaunal composition and diversity at two stations in the eastern and western Fram Strait

The Artic polar deep-sea is one of the least explored ecosystems of the world. With the help of camera surveys, more information is being collected on the composition of megafauna, as well as the environmental factors on the deep-sea floor. The megafauna play an important role in contributing to the benthic biomass and the environmental factors shape this habitat, e.g. through large stones or other hard substrate which animals can settle on. In this thesis, two stations, which are influenced by different water masses, are compared to see how different the communities are. The first station is HAUSGARTEN IV, which is influenced through the warmer West Spitsbergen Current. The second station is east Greenland IV, which is influenced through the colder East Greenland current. Both are 2.500 m deep and run at comparable latitude. HAUSGARTEN is part of a Long-Term-Ecological Research project in the eastern Fram Strait run by the Alfred-Wegener-Institute Bremerhaven. The east Greenland station was established in the western Fram Strait in 2014. This is also the year the images from this thesis were taken during a research cruise of the ice breaker Polarstern. At east Greenland IV the megafauna densities (20.67 ±0.011 individuals/m²) were significantly higher than at HAUSGARTEN IV (15.67 ± 0.040 individuals/m²). This study also focused more closely on the composition at east Greenland IV, as it was the first time this transect was analysed. No significant differences were found between the three sub-sections at east Greenland. While comparing both the stations among each other as well as comparing the three sub-sections, the key species, which caused differences in composition were determined as well as the composition of the megafauna on the deep-sea floor. Environmental factors as well as ice-coverage and the biogeochemistry data of the sea floor were analysed, to see if they influenced the species composition