DEVELOPMENT OF A SIMPLE BENTHIC-PELAGIC COUPLING ECOSYSTEM MODEL AND ITS APPLICATION TO THE REPRODUCTION OF 23YEARS OF WATER QUALITY

Abstract

 We developed a simple benthic-pelagic coupling ecosystem model to understand changes in long-term water quality. A features of this model is the division of pelagic and benthic ecosystem models, and the calculation of each ecosystem component individually. The method used an existing two dimensional vertical pelagic ecosystem model designed at a macro-scale for long-period prediction coupled to a simple one dimensional vertical benthic ecosystem model configured with Phosphorus and Oxygen bio-chemical processes. Using the coupled ecosystem model, we reproduced the water quality of Ofunato Bay from 1993 to 2015. This suggested that the deposition rate of detritus and the concentration of organic matter at the seabed were decreased due to increased seawater exchange resulting from the collapse of a breakwater at the mouth of bay during the 2011 Tohoku earthquake tsunami.