资源环境科技发展态势分析平台

The continuous ecological studies at the HAUSGARTEN have already demonstrated a number of interesting trends. The widespread idea that deep-sea ecosystems only respond very slowly, if at all, to environmental changes in the surface water needs to be revised. For instance, between 2005 and 2008, an episodic and marked increase in the water temperature in the Fram Strait of roughly 2 °C led to profound changes in the phytoplankton communities in the light-flooded surface water. The smaller organisms that live at and in the deep seafloor responded rapidly, since these organisms feed exclusively on dead plankton that sink to the seabed. The number and species composition of larger bottom dwellers reacted more slowly, with a delay of roughly a year. 

The intermittent warm water influxes between 2005 and 2008 caused changes in the marine ecosystem in the Fram Strait, which among others led to the migration of sub-polar and boreal species of zooplankton from farther south, offer a first glimpse of the ecological conditions that can be expected in a warmer and increasingly ice-free Arctic Ocean. Since then, the water temperatures in the Fram Strait have fluctuated relatively little, but a look back at the temperature development over the last 20 years confirms the global trend of continually rising water temperatures. A similar trend, although with a less steep gradient, was found even at depths of 2500 m in the HAUSGARTEN area.  

“Even after 20 years of intensive observations at the HAUSGARTEN observatory, we still can’t say with complete certainty whether the changes detected are a reflection of the natural variations in a marine polar ecosystem, or whether the trends seen are the result of anthropogenic climate change, and so possibly permanent,” says Thomas Soltwedel. Using a modelling approach, a recent scientific study demonstrated that time series for roughly 30 years are needed in order to differentiate between climate-change driven changes in the marine ecosystem and natural variability, and to develop robust prediction models. At HAUSGARTEN, roughly two thirds of this time span has already been covered. Currently, the long-term observations are continuing during the ongoing Polarstern expedition PS121.