Regime shifts in North Sea and Baltic Sea: A comparison

Abstract

The ICES subdivisions in the North Sea (SD IIIa, SD IVa, and SD IVb) and the subdivisions in the Baltic Sea (SD 29, SD 27/28-2, and SD 25/26) are selected to compare the response in long term monitoring data (1970–2000) with respect to climate regime shifts. A modified AMOEBA model is applied to the data sets to identify the status and development of the North Sea and Baltic Sea system during two recent regime shifts. Biological regime shifts can be identified 1989/1990 in SD IIIa in the North Sea and in SD 25/26 in the Baltic Sea. A synchronous appearance of regime shifts could only be identified in the central and southern Baltic Sea for both regime shifts 1975/76 and 1989/90 where the AMOEBA model indicated a high similarity in ecosystem response. A clear difference was identified in the response of the North Sea and the Baltic Sea. Inter-annual and inter-decadal variability as well as regime shifts are driven in the Baltic Sea by direct atmospheric forcing only. In contrast, the changes in the North Sea are influenced by both the direct atmospheric forcing and the indirect forcing from the changes in North Atlantic.The fact that regime shifts as well as their synchronous appearance can be identified with the AMOEBA model might be of major interest for the management of sustainable use of ecosystem goods and services, the development of ecosystem approach to management and the implementation of the Marine Strategy Framework Directive (MSFD) of the European Union (EU).