Evaluating the Bioremediation Capacity of the Polychaete Perinereis gualpensis (Jeldes, 1963) for Atlantic Salmon Aquaculture Sludge

The potential of polychaetes for the bioremediation of aquaculture sludge gained more attention in recent years. These organisms can reduce organic matter and nutrients contained in the sludge of several aquaculture species, improving the sustainability of these activities. The aim of this study was to evaluate the removal performance of Perinereis gualpensis (Jeldes, 1963) being fed with aquaculture sludge produced by a recirculating system cultivating Atlantic salmon. The experiment involved adding different amounts of sludge (10% and 20% with respect to total substrate) at a density of 300 organisms m−2 during 30 days. A treatment without sludge served as a control, using natural substrate. The highest removal rate of total organic matter (TOM) (23.95 ± 13.19 g m−2 day−1) was achieved by P. gualpensis with 20% sludge addition, a reduction of about 36% compared to the total amount added at the beginning of the trials. The organisms fed with aquaculture sludge presented higher nitrogen (8–9%) and carbon (40–43%) contents, with a maximum organic carbon assimilation of 32% in relation to the total content in the sludge. The high survival (88–95%) and positive growth rates (0.28% day−1) achieved by P. gualpensis indicated that this species can be sustained with salmon sludge as the only source of food. These results indicate that P. gualpensis is a promising candidate for removing nutrients from salmon effluents. Moreover, the protein contents achieved by the organisms (52–58%) meet the dietary protein requirements of several aquaculture species. Further research is needed to determine the maximum bioremediation capacity of this species and to evaluate the lipid content and fatty acid profiles of P. gualpensis to determine its potential application in aquaculture feed.