776 / 2024-09-19 12:32:49

Quantitative assessment of nitrogen removal via floating oyster aquaculture

nitrogen removal,subtropical bay,oyster aquaculture,Flux inventory model

As one of important coastal anthropogenic activities, oyster aquaculture has ecological benefit in mitigating coastal eutrophication by removing nitrogen via biomass harvest, microbial denitrification in both oyster body and sediment below. However, there is lack of research on the nitrogen removal quantification via floating oyster aquaculture by denitrification in oyster body separately and assessment in subtropical estuary of China. The Shenzhen Bay (SZB) in southern China has unique large-scale floating oyster aquaculture for direct quantification of oyster-induced nitrogen removal. Utilizing laboratory results extrapolation, oyster yield and a “Flux Inventory Model”, the daily oyster-induced nitrogen removal in harvest season of SZB were quantified into three pathways. This removal was estimated to be 27.6 kg-N km^-2 day^-1, in which biomass harvest, denitrification by oyster and in sediment contributed 31%, 17% and 52%, respectively. Adding exported nitrogen from water column to the sediment via oysters’ filter feeding lifestyle, the increase of total nitrogen loading in SZB could be reduced by 3% in harvest season. This study provides a working framework for quantitative assessment of coastal nitrogen removal by the growing scale floating aquaculture and supply evidence of an anthropogenic nutrient management approach in coastal environment.