Abstract
Corsican marine aquaculture is one of the highest contributors of fish production in France, which may result in environmental perturbations caused by organic matter (OM) accumulation under fish farms and impacting natural communities. This study aimed to (1) characterise the environmental conditions at two different fish farms, (2) monitor the response of benthic foraminiferal species to this activity, and (3) assess the accuracy of existing foraminiferal biotic indices. In 2017, sea floor sediment was sampled in transects from two Corsican fish farms for living foraminiferal and sedimentary analyses. Four indices were calculated and compared: exp(H′bc), Foram-AMBI, Foram Stress Index and TSI-Med. A significant increase in total organic carbon (TOC) has been shown, mainly below the fish cages. Communities were characterized by a shift from high density, opportunistic and tolerant species under the cages to lower densities and more sensitive species further away. According to their distribution patterns along the TOC gradient, we propose to update the ecological group classification of seven species to improve Foram-AMBI’s accuracy and sensitivity: Triloculina oblonga and Quinqueloculina lamarckiana to Ecological Group (EG) I; Rosalina bradyi to EGIII; and Bolivina dilatata, Bulimina aculeata and Quinqueloculina stalkeri to EGIV. We recommend prioritising the use of TSI-Med and Foram-AMBI with the updated list to assess ecological quality in coastal waters of the Mediterranean Sea.
Highlights
With an ever-increasing global demand for fish, aquaculture has been developed to counterbalance and to limit the impact of fisheries on marine biodiversity and biomass
A Limited Effect of Fish Farming on Habitat Features In Corsica, sites B and D correspond to large aquacultures with high annual productions and higher fish densities and food inputs compared to other fish farms on the island
The present findings further suggest that the diversity index exp(H bc) may not be accurate to evaluate environmental quality in oligotrophic coastal ecosystems such as coastal waters in the Mediterranean Sea; this index seems to be better adapted to more sheltered environments in the Mediterranean Sea [50,54]
Summary
With an ever-increasing global demand for fish, aquaculture has been developed to counterbalance and to limit the impact of fisheries on marine biodiversity and biomass. Aquaculture provides about 42.2% of worldwide fish production [1,2]. In the Mediterranean Sea, the sea bass (Dicentrarchus labrax) and the gilt-head sea bream (Sparus aurata) are among the most harvested fishes (Greece, Spain or France) [3]. The impact of fish farms on the surrounding environment is widely acknowledged, mainly due to the accumulation of organic matter (OM) under the cages; up to 30% of the organic matter in the sediment below the cages being non-consumed food [5]. In addition to food-related releases, feces of fishes accumulate, corresponding to up to
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
