Anaerobic degradation of excess protein-rich fish feed drives CH4 ebullition in a freshwater aquaculture pond
Year: 2024
Type: article
Abstract: Aquaculture is a climate-relevant source of greenhouse gases like methane. Methane emissions depend on various parameters, with organic matter playing a crucial role. Nevertheless, little is known about the composition of organic matter in aquaculture. We investigated the effects of excessive loading of high-protein fish feed on the quality of sediment organic matter in a fishpond to explain extremely high methane ebullition rates (bubble flux). Analysing the molecular composition of water-extractable organic matter using LC-FT-ICR MS, we found strong differences between the feeding area and open water area: low-molecular weight nitrogen and sulphur-rich organic compounds were highly enriched at the feeding area. In addition, methane ebullition correlated well with sediment protein content and total bound nitrogen in pore water. Our results indicate that feed proteins in the sediments are hydrolysed into oligopeptides (CHNO) and subsequently converted to CHOS and CHNOS components during anaerobic deamination of protein and peptide fragments in the presence of inorganic sulphides. These metabolites accumulate at the feeding area due to continuous feed supply. Our findings illustrate the adverse effects of excessive feeding leading to bioreactor-like methane emissions at the feeding area. Improving feed management has the potential to make aquaculture more climate-friendly.
Institution: Helmholtz Centre for Environmental Research
Language: English
Subfield: Environmental Chemistry
Field: Environmental Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,990
Award: G1479807391
OpenAlex ID: W4402879329