Pollution from Fish Farming Activities in the Adriatic Sea

Abstract

Fish farming (sea bream and sea bass, as well as bluefin tuna) production in Croatia exhibited a large increment from <1,500 t per year in 1997 to >14,000 t per year in 2018. This expansion has led to enhanced concern for the environmental integrity of the coastal areas from the public and the scientific community, particularly regarding ecological impact of fish farming. To reduce pollution caused by these activities in Croatia, monitoring of physical, chemical and biological parameters in the water column and sediments was introduced. According to Croatian legislative, monitoring activities are based on Environmental Impact Assessment studies (EIAs) for particular fish farm facility. These monitoring programs are not unified considering the parameters to be monitored as well as criteria or standards applied. Similar situation of different monitoring practice of environmental impact of fish farming based on EIAs can be found on European and Mediterranean level. In this chapter an overview of physicochemical parameters monitored at Croatian fish farms is given. On the example of one sea bass and sea bream farm, methodology of sampling and analysis of the water column and sediments is presented as well as the obtained results. Analysed parameters from the water column were: oxygen concentration, pH value, dissolved phosphorus (inorganic and organic), inorganic nitrogen (sum of nitrates, nitrites and ammonia), organic nitrogen concentrations. Parameters determined in sediments were : phosphorus, organic carbon, total nitrogen content and sediment redox potential. According to the presented results parameters in sediments such as phosphorus concentration and redox potential proved as very good indicators of fish farm generated pollution, while from the water column, dissolved inorganic nitrogen form ammonia and organic phosphorus indicated changes caused by farming activities. Parameters proposed to be monitored in sediment represent the organic matter content (carbon, nitrogen and phosphorus) and the degree of its degradation (redox potential). Their analyses are not expensive and they are feasible to obtain. Majority of parameters monitored in the water column are already included in the water quality analysis that are monitored for the commitments of European directives (WFD, MSFD) or Mediterranean plans (IMAP), and their interpretation can be obtained in accordance with the existing threshold values. Brief overview of Montenegrin mariculture activities, legislation, monitoring and perspectives is also given to compare with Croatian experiences. It can be summarized that presented Croatian monitoring design of physicochemical parameters in water column and particularly in sediments can be applicable example of future monitoring practice on the Montenegrin fish farm facilities.