AN ANALYSIS OF BENTHIC BIOLOGICAL DYNAMICS IN A NORTH-SEA ECOSYSTEM MODEL

This paper presents an overview and analysis of the benthic biological submodel of the European Regional Seas Ecosystem Model II (ERSEM II). This submodel consists of a detailed model description of the benthic system which is integrated with a marine ecosystem model which attemp ts to address the full range of pelagic and benthic biogeochemical and physical processes. The submodel simulates the seasonal dynamics of a number of functional groups, ranging from decomposers to predators an d their interaction with detrital matter in the sediments. The improve ments and extensions to the benthic biology submodel compared with the previous published version of the European Regional Seas Ecosystem Mo del are described. The improvements comprise: the reformulation of tur bation and irrigation as functions of faunal activity, the inclusion o f oxygen stress limitations and mortalities, a refinement of the descr iption of detritus, additions to the diet of the filter feeders in lin e with the extensions to the primary production module and an extensiv e re-parameterisation. Using the 1 degrees x 1 degrees North Sea appli cation, the submodel predictions are compared with data and the perfor mance of the submodel assessed. Using the results of the submodel, the relation between benthic biological dynamics and its principal determ inants, depth and overlying production is examined. The model is found to give qualitatively correct results. The transition in community ty pe from anaerobe/deposit feeder in the south to a more mixed community in the north, involving aerobes and meiobenthos is also correctly pre dicted by the model. The biology is demonstrated to have a strong infl uence on nutrient efflux. The lack of resuspension/deposition processe s is identified as the most significant omission from the current mode l. (C) 1997 Elsevier Science B.V. All rights reserved.