Modelling the effects of net pens to the marine ecosystems

Advances in the field of aquaculture has resulted in increased production during the last two decades and today aquaculture produces 50% of the world?s seafood. A considerable portion of this production comes from cage (net pen) aquaculture in coastal areas. However, the development of marine aquaculture along the coastal areas raises concerns about the sustainability of natural environment. The effects of aquaculture can be deleterious by increasing turbidity through over-feeding and poor waste management. In Turkey, the majority of potential environmental concerns is of a speculative nature and in many cases is not supported by scientific evidence.The current project aims to determine the effects of marine cage farms located in coastal regions in western Turkey with a view to suggesting procedures for better management in the planning and impact assessments and to assisting in the evaluation of future projects. An important part of this study concerns simulating the accumulation of organic material by a modeling software (MERAMOD) using field data collected during 2 years. We have also compared simulation results with data collected from sediment traps.Field data indicated that sedimentation rates ranged between 0,05-58,85 g/m2/day. However, computer simulations on sedimentation rate of organic material were significantly less than those of field data. Therefore, there is a need to validate simulations against data collected from sediment traps. Total organic carbon accumulation rates ranged between 0,55-648,9 g/m2/year. The organic enrichment of the seabed directly beneath the cages was the most prominent result of the sedimentation of particulate waste due to feeding and fecal wastes. It is in the interest of governmental agencies to integrate a multi-disciplinary approach in order to determine potential cage farm sites to develop sustainable management strategies.