Relationship between sedimentation rates and benthic impact on Maërl beds derived from fish farming in the Mediterranean

• Published in: Marine environmental research 2011-02, Vol.71 (1), p.22-30
• Main Authors: Sanz-Lázaro, Carlos, Belando, María Dolores, Marín-Guirao, Lázaro, Navarrete-Mier, Francisco, Marín, Arnaldo
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal aquaculture; Animal productions; Animal, plant and microbial ecology; Aquaculture; Biological and medical sciences; Carbon; Carbon - analysis; Communities; community structure; Dispersions; Ecosystem; ecosystems; Environment; Environmental Monitoring; farming systems; Farms; Finfish aquaculture; Fish; fish culture; Fish farming; fish farms; Fundamental and applied biological sciences. Psychology; Geologic Sediments - chemistry; habitats; Marine; marine fish; Mediterranean; Mediterranean Sea; nitrogen; Nitrogen - analysis; nutrients; Particulate wastes; phosphorus; Phosphorus - analysis; physicochemical properties; Pisciculture; Sea water ecosystems; Seawater - chemistry; Sedimentation; sediments; Synecology; Trophic groups; Vertebrate aquaculture; Wastes; Water Movements; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - chemistry
• ISSN: 0141-1136; 1879-0291
• DOI: 10.1016/j.marenvres.2010.09.005

The aim of this work was to study the dispersion of particulate wastes derived from marine fish farming and correlate the data with the impact on the seabed. Carbon and nutrients were correlated with the physico-chemical parameters of the sediment and the benthic community structure. The sedimentation rates in the benthic system were 1.09, 0.09 and 0.13 g m −2 day −1 for particulate organic carbon (POC), particulate organic nitrogen (PON) and total phosphorus (TP), respectively. TP was a reliable parameter for establishing the spatial extent of the fish farm particulate wastes. Fish farming was seen to influence not only physico-chemical and biological parameters but also the functioning of the ecosystem from a trophic point of view, particularly affecting the grazers and the balance among the trophic groups. POC, PON and TP sedimentation dynamics reflected the physico-chemical status of the sediment along the distance gradient studied, while their impact on the benthic community extended further. Therefore, the level of fish farm impact on the benthic community might be underestimated if it is assessed by merely taking into account data obtained from waste dispersion rates. The benthic habitat beneath the fish farm, Maërl bed, was seen to be very sensitive to aquaculture impact compared with other unvegetated benthic habitats, with an estimated POC-carrying capacity to maintain current diversity of 0.087 g C m −2 day −1 (only 36% greater than the basal POC input). Environmental protection agencies should define different aquaculture waste load thresholds for different benthic communities affected by finfish farming, according to their particular degree of sensitivity, in order to maintain natural ecosystem functions. ► The carrying capacity for POC to maintain current diversity was 0.087 g C m -2 day -1. ► Fish farm impact might be underestimated if assessed only with dispersion waste data. ► Fish farming modified the macrofaunal benthic community in a functional way.