Study Of The Effects Of Ocean Acidification And Warming On Diatom-Shellfish Metabolome

Since the industrial revolution,human activities have produced large amounts of greenhouse gases,leading to increasing atmospheric CO₂ concentrations.Such change not only leads to climate warming,but also causes a series of marine environmental problems such as ocean acidification and seawater warming.According to the projection,if the current rate of climate change continues,serious consequences for marine ecosystems and marine organisms will happen.Therefore,it has become increasingly important to study how marine organisms respond and adapt to climate change factors.Diatoms,which contribute one-fifth of global carbon fixation,and shellfish,a popular economic seafood,deserve particular attention as representative ocean organisms.How they interact individually and jointly through the food chain to face the impacts of global change factors such as ocean acidification and warming still needs further study.Most studies have focused on single environmental influence and single species.There is a lack of studies on the coupling effect of multiple factors and on several species.In this paper,we apply metabolomics technique to explore the patterns and mechanisms by which two adjacent trophic levels,the diatom Phaeodactylum tricornutum and the shellfish Coelomactra antiquata,respond to the effects of ocean acidification and warming.We hope to provide a theoretical complement to the ecological picture of marine organisms’adaptation to future global change environments through these studies.The main findings are as follows:（1）P.tricornutum may respond to acidification stress by producing pheophorbide a,canthaxanthin and abscisate and by secreting more glutamate and saturated fatty acids.In addition,the content of metabolic substances such as citric acid and proline in algal cells also changed under specific experimental conditions.These metabolites are expected to be biomarkers of diatoms exposed to ocean acidification.（2）Ingestion of P.tricornutum grown under climate change conditions altered the contents of some amino acids in C.antiquata,such asγ-aminobutyric acid and glycine.Besides,feeding on P.tricornutum grown under warming related conditions increased the amount of pyridoxine in C.antiquata,implying a possible benefit in the immune function of it.In addition,feeding on P.tricornutum cultured under all climate change scenarios led to the down-regulation of taurine content in C.antiquata,but the mechanism behind is still a mystery.（3）The"diatom-shellfish"integrated multi-omics analysis filtered 9 biologically related multi-omics pathway links under warming conditions,with methylation and transcriptome of P.tricornutum sharing the same pathway,terpenoid skeleton biosynthesis pathway.The down-regulation of this pathway may be a response mode for P.tricornutum when exposed to high temperature.Moreover,pantothenate was down-regulated in C.antiquata under warming conditions,which may adversely affect the growth of it.