Water and Sediments Characteristics Influencing Fish Farming Activities: Univariate and Multivariate Approaches

Abstract

Environmental variables, especially water, sediment characteristics and farming practices play important roles in influencing the degree and severity of the impacts of aquaculture. The water-sediment interface under fish farms can be influenced by organic waste in the form of feces and unconsumed feed derived from farm activities. This study focuses on the hydrographical conditions and water chemistry of the bluefin tuna farming area in the southern Spencer Gulf, especially organic carbon content, sediment grain size and current velocity. A comparative study of organic matter and sediment grain size between sites and the relationship between the siltclay fractions of the sediments and the amount of organic matter are assessed. Sediment samples were taken using a HAPS bottom corer equipped with a corer of 67 mm in diameter and 315 mm in length, operated from the research vessel RV Ngerin. The results suggest that hydrographical conditions and water chemistry of southern Spencer Gulf varied slightly depending on the location of the stations sampled. No accumulation in organic matter under the fallowed cages was detected, indicating that the hydrodynamic conditions at southern Spencer Gulf are considered well flushed and thus suitable for farming activities.