Biostimulation of in situ microbial degradation processes in organically-enriched sediments mitigates the impact of aquaculture. (July 2019)

• Record Type: Journal Article
• Authors: Ape, Francesca; Manini, Elena; Quero, Grazia Marina; Luna, Gian Marco; Sarà, Gianluca; Vecchio, Paolo; Brignoli, Pierlorenzo; Ansferri, Sante; Mirto, Simone
• Is Part Of: Chemosphere. Volume 226(2019)
• Page Start: 715
• Page End: 725
• Publication Date: 2019-07
• Subjects: Bioactivator -- Fish farm -- Organic matter -- Extracellular enzymatic activity -- Prokaryotic diversity; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.03.178
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Fish farm deposition, resulting in organic matter accumulation on bottom sediments, has been identified as among the main phenomena causing negative environmental impacts in aquaculture. An in situ bioremediation treatment was carried out in order to reduce the organic matter accumulation in the fish farm sediments by promoting the natural microbial biodegradation processes. To assess the effect of the treatment, the concentration of organic matter in the sediment and its microbial degradation, as well as the response of the benthic prokaryotic community, were investigated. The results showed a significant effect of the treatment in stimulating microbial degradation rates, and the consequent decrease in the concentration of biochemical components beneath the cages during the treatment. During the bioremediation process, the prokaryotic community in the fish farm sediment responded to the overall improvement of the sediment conditions by showing the decrease of certain anaerobic taxa (e.g. Clostridiales, Acidaminobacteraceae and Caldilinaceae). This suggested that the bioactivator was effective in promoting a shift from an anaerobic to an aerobic metabolism in the prokaryotic community. However, the larger importance of Lachnospiraceae (members of the gut and faecal microbiota of the farmed fishes) in treated compared to non-treated sediments suggested that the bioactivator was not efficient in reducing the accumulation of faecal bacteria from the farmed fishes. Our results indicate that bioremediation is a promising tool to mitigate the aquaculture impact in fish farm sediments, and that further research needs to be oriented to identifying more successful interventions able to specifically target also fish-faeces related microbes. Graphical abstract: Image 1 Highlights: Bioremediation reduces the accumulation of organic matter in fish farm sediments. The bioactivator stimulates in situ microbial degradation processes. Bioremediation induces shifts in prokaryotic community composition. A shift from anaerobic to aerobic prokaryotic metabolism is promoted. The treatment is ineffective on the fecal bacteria from farmed fishes.