The sulfur cycle and hydrogen sulfide production in aquatic ecosystems with an emphasis on aquaculture

The sulfur cycle is a complex biogeochemical process in aquatic ecosystems that involved four stages of mineralization, immobilization, reduction and oxidation. In organic matter-rich aquatic ecosystems especially aquaculture ponds, half of organic matter deposited under anaerobic condition by sulfate reducing bacteria and hydrogen sulfide gas produced as by product during this process. Small concentrations of hydrogen sulfides are highly toxic to aquatic organisms and therefore its production must be avoided. On the other hand, degrade of organic matter increases the amount of nutrients (e.g., nitrogen and phosphorus) in water, thus cause eutrophication of the ecosystems. Therefore, sulfur cycle has both positive and negative effect in aquatic ecosystems.