Influences Of Intertidal Wind Farms On Jiangsu Coastal Ecosystem And Its Trophic Flows

Energy is always an important basis for national economic development.As countries all over the world begin to realize the need for mitigation of global warming and energy crisis,exploitation and harness of offshore wind farms were tried and developed in America and European countries such as Germany,Belgium,UK and Denmark.With better potential of wind energy,less construction cost and reduced difficulty of installation,intertidal wind farms are economically appropriate for Jiangsu coastal area.However,in terms of the environmental vulnerability due to land-sea interactions in intertidal zones and ecosystem value due to its high productivity and biodiversity,there is an urgent need to figure out how wind farms influence the intertidal ecosystem and its trophic flows in Jiangsu coastal area.In this paper we developed two mass-balance(Ecopath)models applying Ecopath with Ecosim software 6.4.3 for the intertidal ecosystem in Jiangsu coastal area.Input data were mainly from the information collected in marine ecology surveys during 20062007 and a further marine biological research on wind-farm influences during 2015 funded by a national natural science fund project.By comaring the two Ecopath models respectively representing the Jiangsu intertidal ecosystem before and after the construction of wind farms,we evaluated the system attributes,trophic structure,and energy flow,analyzed the process and mechanism of how intertidal wind farms exerted impacts on the ecosystem,and briefly summarized the characteristics of the impacted ecosystem also.The model included 14 functional groups covering the main trophic flow,which were detritus,phytoplankton,zooplankton,benthos,squids,crabs,shrimps,archovies,Sciaenidae,Gobiidae,Pleuronectiformes,Anguilliformes,other Pelagic Fish and other benthic fish.The balanced model suggests that the system has been changed by wind farms.Wind turbines were arranged in the intertidal zone,which added hard rocky substrates in the area and altered the waves and tidal currents.Resuspension occurred frequently when currents passed wind turbines leaving wake streams and vortex in the different directions of them,and this resuspension helped detritus organic particle disperse and added its opportunity of capture by filter feeders such as zooplankton.Increase of zooplankton made it possible for secondary consumers such as shrimps,crabs,squids,and small-sized fish to be fed.On the other hand,water transparency was lowered,so production of phytoplankton decreased because of hindrance of photosynthesis.Disturbance of water was beneficial for some species to disperse propagules intensively and find a perfect low-energy location to get settled while it was detrimental to the survival of some fish due to damages caused by current impacts and frictions.Submarine environments were also modified due to changed sedimentary and erosion rates.These changes in the habitat directly or indirectly affected survival and reproduction of different functional groups in the ecosystem,thus leading to changes in dominant groups and trophic flows.Trophic levels of top predators were lowered and trophic levels of shrimps,crabs and small fish were raised,indicating that the composition species in the ecosystem has changed and functional groups with lower tropic level has obtained dominance.The whole ecosystem is still in the developing process,while its energy cycling proportion,system complexity and maturity are increasing.Overall,intertidal wind farms have played an active role in the maturity of the ecosystem.Therefore,it is suggested that the Jiangsu intertidal wind farms should be kept running and expanded to a larger intertidal scale,especially in ecologically vulnerable areas caused by overfishing,pollution,eutrophication and other human activities,to help heal these costal ecosystems while harnessing clean renewable energy.