Expected Biological Effects of Long-Term Changes in Temperatures on Benthic Ecosystems in Coastal Waters Around the Netherlands

Abstract

A comparison between the course of air temperatures during the last century (either on a global scale or at De Bilt) with temperatures of Dutch coastal waters shows that the temperatures in Dutch coastal waters are not only determined by air temperatures; hydrographical alternations on the North Atlantic Ocean will have had a clear influence too.

A comparison of the macrobenthic fauna of the Wadden Sea with those of the Seine estuary (mean temperatures 2°C higher) and the Gironde estuary (mean temperatures 4°C higher) leads to the conclusion that at a rise in temperature of 2°C an enrichment of ~20% of the number of species would occur, whereas at a rise of 4°C an enrichment of ~30% might be expected.

In the warmest period of the Eemien (Pleistocene) the annual mean water temperature in the Eemien Sea was about 14–15°C, compared with ~10°C for the present Dutch Wadden Sea. All species of molluscs known from the Eemien still occur in Europe, and a good resemblance exists between the molluscs species of the Dutch Eemien and the recent ones of Arcachon Bay. This supports the above conclusion.