Ocean Deoxygenation Conference | Kiel 2018

Globally, climate change influences marine ecosystems. Superimposed on these mean changes are extreme events such as heat waves, freshening events or wind-driven upwelling, causing deoxygenation of surface waters. Both, mean changes and extremes will certainly stress marine species and ecosystems. Marginal, often shallow, seas are particularly affected by environmental variability of various drivers, at various scales. While a vast majority of literature now focuses on the significance of extreme events and environmental variability in the context of climate change research, experimental evidence is still lacking. In the framework of this project, we aim on elucidating the interplay between marine heat waves and hypoxic upwelling events on Western Baltic Sea marine benthic communities. The occurrence of heat waves and upwelling events will be modelled for the Kiel Fjord area and trends of changing frequencies and amplitudes will be clarified. In the following, the effect of modelled characteristics of heat waves followed by upwelling events will be experimentally investigated on two typical Baltic Sea benthic communities: a seagrass- and a secondary hard-bottom community. This will allow more realistic conclusions on the effect of ongoing climate change, including extreme events, on important benthic communities, and on the interplay between multiple relevant stressors. Modelling on past and current events as well as the applied experimental work will form the basis for designing guidelines for the management of local ecosystems. Through the interaction of scientists, local industry (aquaculture and fishery) and tourism, the needs for possible forecasts of these extreme events will be evaluated as well as the potential for an extreme event warning system (EEWS). This EEWS, along with mitigation guidelines, can, thus, be used to reduce additional anthropogenic stress on local ecosystems during extreme events.