Nutrient discharge from China’s aquaculture industry and associated environmental impacts

Abstract

China's aquaculture industry accounts for the largest share of the world's fishery production, and provides a principal source of protein for the nation's booming population. However, the environmental effects of the nutrient loadings produced by this industry have not been systematically studied or reviewed. Few quantitative estimates exist for nutrient discharge from aquaculture and the resultant nutrient enrichment in waters and sediments. In this paper, we evaluate nutrient discharge from aquacultural systems into aquatic ecosystems and the resulting nutrient enrichment of water and sediments, based on data from 330 cases in 51 peer-reviewed publications. Nitrogen use efficiency ranged from 11.7% to 27.7%, whereas phosphorus use efficiency ranged from 8.7% to 21.2%. In 2010, aquacultural nutrient discharges into Chinese aquatic ecosystems included 1044 Gg total nitrogen (184 Gg N from mariculture; 860 Gg N freshwater culture) and 173 Gg total phosphorus (22 Gg P from mariculture; 151 Gg P from freshwater culture). Water bodies and sediments showed high levels of nutrient enrichment, especially in closed pond systems. However, this does not mean that open aquacultural systems have smaller nutrient losses. Improvement of feed efficiency in cage systems and retention of nutrients in closed systems will therefore be necessary. Strategies to increase nutrient recycling, such as integrated multi-trophic aquaculture, and social measures, such as subsidies, should be increased in the future. We recommend the recycling of nutrients in water and sediments by hybrid agricultural-aquacultural systems and the adoption of nutrient use efficiency as an indicator at farm or regional level for the sustainable development of aquaculture; such indicators; together with water quality indicators, can be used to guide evaluations of technological, policy, and economic approaches to improve the sustainability of Chinese aquaculture.

Potential of aquacultural sludge treatment for aquaponics: evaluation of nutrient mobilization under aerobic and anaerobic conditions

“…Public perception of aquaculture is often critical, raising concerns about eutrophication and pollution of the aquatic environment due to direct emissions of nutrients from fish farms (Edwards 2015, Zhang et al 2015. Often ignored, solid waste originating from faeces and uneaten feed pellets represent a substantial nutrient reservoir.…”

“…Often ignored, solid waste originating from faeces and uneaten feed pellets represent a substantial nutrient reservoir. Upon microbial conversion, chemical mobilization and leaching, nutrient emissions may induce algal blooms, oxygen depletion and mass mortalities among aquatic organisms (Zhang et al 2015). Over the last 2 decades, recirculating aquaculture systems (RAS) have been rapidly evolving to reduce such impacts on the environment.…”

Farming system transformation yields significant reduction in nutrient loading: Case study of Hongze Lake, Yangtze River Basin, China

“…This transformation was triggered as a result of the rapid development of intensive aquaculture of Chinese major carps that threatened the sustainability of Hongze Lake because of eutrophication resulting from excessive use of fertilizer and feed, as reviewed by Zhang et al (2015). There was a corresponding realization of the need to minimize the environmental impacts of aquaculture and alternatives introduced that would still provide livelihood and economic opportunities to the communities engaged in fish farming.…”

Sustainable farming practices of the Chinese mitten crab (Eriocheir sinensis) around Hongze Lake, lower Yangtze River Basin, China

“…Rapid development of intensive aquaculture, primarily of Chinese major carps, threatened the Electronic supplementary material The online version of this article (doi:10.1007/s13280-015-0722-0) contains supplementary material, which is available to authorized users. sustainability of the Hongze Lake wetlands through eutrophication resulting from excessive use of fertilizer and feed (reviewed by Zhang et al 2015). As such, there was a need to minimize the environmental impacts of aquaculture and alternatives introduced that would still provide livelihood and economic opportunities to the local communities engaged in fish farming.…”