Organic enrichment of sediments from freshwater aquaculture

Aquaculture is steadily expanding and has become a vital source of food and income globally. However, this growth also exerts increasing pressure on aquatic ecosystems. Net-cage aquaculture releases effluents, primarily organic matter, which can cause environmental impacts that vary in severity depending on production intensity and site characteristics. Norway developed the MOM system (Monitoring, Ongrowing fish farms, Modelling) to monitor the environmental impact in marine environments. This study evaluates, for the first time, the MOM system’s applicability to assess the impact of aquaculture in freshwater environments. Sediment samples were collected from Lake La Cocha in Colombia, near three fish farms with different production levels, as well as from two reference sites. The analysis followed the Norwegian MOM protocol, which considers three groups of parameters: the presence/absence of fauna (Group I), pH and redox potential (Group II), and the “sensory” characteristics of the sediments, such as color, odor, and the presence of gas bubbles (Group III). The results indicate that, overall, sediments near the studied farms were in very good to good condition. However, a decrease in pH associated with organic enrichment was observed, along with signs of gas release, reduced sediment consistency, and increased sample volume. These changes suggest sedimentary impacts related to freshwater aquaculture. The results indicate the need for additional measurements and observations of various parameters—including redox potential, color, deposit thickness, and odor—to improve system characterization in continental environments. These findings represent a significant step toward developing an environmental monitoring protocol for freshwater aquaculture. Incorporating data from diverse water bodies and production levels will help refine this protocol and support more sustainable aquaculture development in Colombia

Aquaculture · Biology · Fish · Fishery · Geotechnical engineering · Environmental Science · Water Quality Monitoring and Analysis · Geology · Oceanography