Resource Use In The Chinese Mariculture Industry

China is the biggest producer of aquaculture products,accounting for 62%and 48%of the total production of aquatic animals and plants,respectively.The rapid growth of the industry has generated concerns about its negative effects on sustainable development.The environmental impacts of aquaculture expansion include changes in land and sea use,the release of waste and effluents to local ecosystems,and the overexploitation of natural resources,and they will ultimately affect the provision of ecosystem services that constitute the livelihood of many communities worldwide.Most studies published to date have focused in the impacts of freshwater and brackish water systems,and have assessed the environmental burden of the production of a few relevant species.However,the impacts of mariculture systems have received comparatively less attention,despite the broad impacts of these systems over coastal ecosystems and local communities.In China,the mariculture sector is expanding at a fast rate and its environmental and socioeconomic impacts are intensifying,but very few studies related to these issues have been conducted.The life cycle assessment(LCA)has become the main tool used to assess the performance of aquaculture systems.This research field has evolved considerably,from small case studies conducted on single species to publications that conduct regional assessments and propose methodological improvements.The main results of the assessments reported to date are the high environmental cost of feed,the release of nitrogen and phosphorus effluents to water bodies,and the differences in impacts between various production intensities.However,the variety of choices and approaches taken by researchers when conducting these analyses is considerable and many issues still remain unresolved,including optimal allocation procedures and uncertainty quantification.This study quantifies the resource use in the production of six of the main mariculture products farmed in China:Large yellow croaker(Larimichthys crocea),sea cucumber(Apostichopus japonicus),abalone(Haliotis spp.),kelp {Laminaria japonica),gracilaria(Gracilaria spp.),and laver(Porphyra spp.).The study took the city of Ningde as a case study,and employed the LCA framework and the Cumulated Exergy Demand indicator to quantify resource use.A Monte Carlo simulation was used to account for the uncertainty in the results,including the inherent uncertainty,spread and unrepresentativeness of the data,and also account for the correlation among process chains and among unit process variables.Correlation among unit process variables is often not included in LCA models,and its effects on the final results were thus analyzed.The results show that the main contributors to resource use in animal and seaweed production are the feed and fuel,respectively.In animal production,the analysis also indicates that the amounts of feed used exceeds the biomass obtained 4 times in large yellow croaker,8 times in sea cucumber and 40 times in abalone production.The impact assessment shows that the mean exergy demand values of the production of one live-weight ton of large yellow croaker,sea cucumber,abalone,kelp,gracilaria,and laver are 106 GJ eq.,65 GJ eq.,126 GJ eq.,0.25 GJ eq.,1.55 GJ eq.,and 0.98 GJ eq.,respectively.For animal products,45%-90%of the impacts come from the feed requirements,while in seaweed production over 80%of the impacts are linked to the fuel used in operation and maintenance activities.Additionally,the results indicate that the environmental impacts of mariculture production are geographically distributed over wide areas,particularly in the production of animal products.Overall,local mariculture shows high variability in both amounts of inputs and environmental impacts among farms.Finally,the assessment also shows that the inclusion of correlation among unit process variables generally have a considerable effect on the final results.This effect is particularly evident in the estimates of variability,with changes ranging between 3%-18%.Policies oriented to improve resource management should thus take the feed and fuel consumption as the main targets to guide current practices into more sustainable ones.Improvements in farm design and input management,implementation of training programs and production standards,and a more formal spatial planning of mariculture areas can effectively reduce the resource consumption and improve the efficiency of local mariculture production.All these measures may additionally reduce other environmental and socioeconomic impacts,both at the local and global scales.Regarding modeling issues,correlation among unit process variables should be included as part of the uncertainty analysis when possible,due to the importance it may have on the final results.