Meiofauna as an indicator for assessing the impact of fish farming at an exposed marine site

This study aimed to detect the impact of organic loads due to biodeposition from a fish farm in an exposed area of the Strait of Sicily, Mediterranean Sea. Sediment chemistry and meiofaunal assemblages were investigated on a seasonal basis at four stations: two from the impacted area and two control stations. The presence of the cages induced a significant accumulation of proteins, lipids and biopolymeric carbon, resulting in a reduction in meiofaunal density at the impacted stations. Changes in community structure were also evident, as meiofauna under the cages were characterized by increased importance of polychaetes and copepods in comparison with a much lower importance of gastrotrichs and kinorynchs. Moreover, biodiversity decreased beneath the cages due to the disappearance of taxa more sensitive to organic accumulation. This finding allowed us to propose the ration of nematodes to kinorynchs as a possible, potentially interesting, indicator of fish farm biodeposition.