Effect Of Multiple Pressure On Coastal Ecosystem Function

Coastal ecosystems account for more than one-third of the world’s ecosystem services,and supporting more than fifty percent of the world’s population and ninety percent of the fishery.The risk assessment of coastal ecosystem services and output function,phytoplankton adaptability,and food safety under multiple pressures which including coastal pollutants(petroleum hydrocarbons and heavy metals),eutrophication,and acidification is essential.In this paper,phytoplankton and bivalve molluscs have been used as model,and biomass,life cycle,nutrition value,photosynthesis,respiration,antioxidant capacity,lipid peroxidation,the degradation of petroleum hydrocarbons,and metals bioavaibility are determined to discuss:(a)the influence of the coexistence of acidification and eutrophication on phytoplankton physiological functions,(b)marine phytoplankton adaptability and self-purification capacity under petroleum hydrocarbon contamination,and(c)effect of coastal eutrophication on heavy metal bioaccumulation and oral bioavailability in the razor clam,Sinonovacula constricta.The results are shown as follows.(1)Conticribra weissflogii was a coastal centric diatom,Prorocentrum donghaiense is a representative of red tide algae,both of which are often used as marine diatoms and dinoflagellates model organism.Here we investigate the effects of nitrate((N,14.3,21.4,28.6,35.7 μmol/L)and phosphate(P,0.48,0.97,1.45 μmol/L))addition and/or coastal acidification(p H,7.80,7.90,8.00,8.10)on Conticribra weissflogii and Prorocentrum donghaiense physiological functions.The influence of N and P addition on malonaldehyde and carbonic anhydrase activity in Conticribra weissflogii and content of chlorophyll a and protein in Prorocentrum donghaiense are significant.In addition,the influence of eutrophication on Conticribra weissflogii nitrate reductase activity is more obvious than the coexistence of acidification and eutrophication.While others physiological functions of these two algaes,the influence of coexistence is more obvious than the single effect of acidification or eutrophication.The influence of eutrophication on physiological functions of diatom and dinoflagellate could be enhanced by acidification,and with the simultaneous deterioration of acidification and eutrophication,dinoflagellate is more adaptable to this change,thus affecting the succession and abundance of diatoms and dinoflagellates in coastal ecosystem.(2)Marine algaes Dunaliella salina,Chlorella sp,Conticribra weissflogii,Phaeodactylum tricornutum Bohlin,and Prorocentrum donghaiense have been used to test their tolerance of petroleum hydrocarbon contamination.P.donghaiense could be used as a biological indicator of petroleum hydrocarbon toxicity on coastal ecosystem functions.D.salina and Chlorella sp can survive in high levels of WSF pollution and then used for hydrocarbon biodegradation.The content of β-carotene in these two speices of algae has significant correlation with WSFs concentrations.WSFs degradation rate is correlated with ·OH and β-carotene concentration.Degradation rate of WSFs was increased with the increasing of ·OH concentration in seawater.The β-carotene has strong antioxidant capacity to protect algal cells from petroleum hydrocarbon toxicity,petroleum hydrocarbons could be biodegraded effectively by algaes.However,the ·OH in seawater can be removed by β-carotene effectively.Therefore,β-carotene as a coin has two sides on the degradation of WSFs.With the increasing of β-carotene content,the degradation rate of WSFs is increased firstly and then decreased for D.salina and decreased totally for Chlorella sp.In general,WSFs in seawater can be degradaed more effectively by Chlorella sp than D.salina.(3)As traditional seafoods,the razor clams are widely distributed from tropical to temperate areas.Coastal razor clams are often exposed to eutrophication.Heavy metal contamination is critical for seafood safety.However,how eutrophication affects bioaccumulation and oral bioavailability of heavy metals in the razor clams is unknown.After a four month field experimental cultivation,heavy metals(Fe,Cu,Ni,V,As,and Pb)could be bioaccumulated by the razor clams(Sinonovacula constricta)through exposure to metals present in water and sediments or in the food chain,and then transferred to human via consumption of razor clams.Bionic gastrointestinal digestion and monolayer liposome extraction are used for metal oral bioavailability(OBA)assessment.The influence of eutrophication on OBA is decreased for Fe and Pb and increased for V.A significant positive linear correlation was observed between the bioaccumulation factors of Fe,Ni,V,and As in razor clams and the coastal eutrophication.These results may be due to the effect of eutrophication on metal species transformation in coastal seawater and subcellular distribution in razor clams.The maximum allowable daily intakes of razor clams are controlled by eutrophication status and the concentration of affinity-liposome As in razor clams.