Interannual zooplankton distribution in the HAUSGARTEN area (eastern Fram Strait) in relation to environmental conditions

Climate change has the potential to significantly affect zooplankton communities. Increasing seawater temperatures, for example, can lead to shifts in species distribution. When large cold-water species with high biomass are replaced by smaller warm-water species with relatively low biomass, this might have strong impacts on the food web dynamics and the whole ecosystem functioning. Since 2011, we are therefore regularly monitoring the summer zooplankton abundance and community composition at HAUSGARTEN, a long-term observatory in the eastern Fram Strait between approx. 3 and 6° E. In this area, the West Spitsbergen Current carries relatively warm Atlantic water masses northward into the Arctic Ocean. Along a north-south transect on the 2500 m isobath between approx. 78.5° N and 80° N, vertical multinet casts (mesh size: 150 µm) were regularly conducted at three stations. Five different depth strata were covered in each haul (1500-1000-500-200-50-0 m). In addition, the optical plankton recorder LOKI (Lightframe On-sight Key Species Investigation), which is equipped with a high-resolution camera as well as sensors for measuring depth, temperature, salinity, oxygen and fluorescence, was deployed at the same stations from 2012 on to investigate the small-scale distribution of zooplankton species down to a depth of 1000 m. To predict how climate change may alter the zooplankton community at the gateway to the Arctic Ocean, the interannual abundance data are discussed in relation to environmental parameters