Oceanic uptake of anthropogenic carbon dioxide results in a decrease in seawater pH, a process known as "ocean acidification". The pearl oyster Pinctada fucata, the noble scallop Chlamys nobilis, and the gre...Oceanic uptake of anthropogenic carbon dioxide results in a decrease in seawater pH, a process known as "ocean acidification". The pearl oyster Pinctada fucata, the noble scallop Chlamys nobilis, and the green-lipped mussel Perna viridis are species of economic and ecological importance along the southern coast of China. We evaluated the effects of seawater acidification on clearance, respiration, and excretion rates in these three species. The animals were reared in seawater at pH 8.1 (control), 7.7, or 7.4. The clearance rate was highest at pH 7.7 for P. fucata and at pH 8.1 for C. nobilis and P. viridis. The pH had little effecton the respiration rate of P. fucata and P. viridis. In contrast, the respiration rate was significantly lower atpH 7.4 in C. nobilis. The excretion rate was significantly lower at pH 7.4 than pH 8.1 for all species. Theresults indicate that the reduction in seawater pH likely affected the metabolic process (food intake, oxygenconsumption, and ammonia excretion) of these bivalves. Different species respond differently to seawateracidification. Further studies are needed to demonstrate the exact mechanisms for this effect and evaluateadaptability of these bivalves to future acidified oceans.展开更多
With the rapid development of oil,energy,power and other industries,CO_(2) emissions rise sharply,which will cause a large amount of CO_(2) in the air be absorbed by the ocean and lead to ocean acidification.The growt...With the rapid development of oil,energy,power and other industries,CO_(2) emissions rise sharply,which will cause a large amount of CO_(2) in the air be absorbed by the ocean and lead to ocean acidification.The growth and development of organisms can be seriously affected by acidified seawater.Sepia esculenta is a mollusk with high nutritional and economic value and is widely cultured in offshore waters of China.Larvae are the early life forms of the organism and are more vulnerable to changes in the external environment.Too low pH will lead to some adverse reactions in larvae,which will affect metabolism,immune response and other life activities.In this study,we sequenced the transcriptome of S.esculenta subjected to acidified seawater stress and identified 1072differentially expressed genes(DEGs).The detected atypical expression of DEGs substantiates cellular malformation and translocation in S.esculenta under low pH stimulation.Simultaneously,this also substantiates the notable impact of ocean acidification on mollusks.These DEGs were used for functional enrichment analysis of GO and KEGG,and the top twenty items of the biological process classification in GO terms and 11 KEGG signaling pathways were significantly enriched.Finally,the constructed proteinprotein interaction network(PPI)was used to analyze protein-protein interactions,and 12 key DEGs and 3 hub genes were identified.The reliability of 12 genes was verified by quantitative RT-PCR.A comprehensive analysis of the KEGG signaling pathway and PPI revealed that ocean acidification leads to abnormalities in lipid metabolism in S.esculenta larvae,which can lead to cancer development and metastasis,accompanied by some degree of inflammation.The results of the study will help to further investigate the physiological processes of S.esculenta when stimulated by ocean acidification,and provide a reference to cope with the captive breeding of S.esculenta affected by acidification.展开更多
Ocean acidification(OA),caused by the rising concentration of atmospheric CO_(2),leads to changes in the marine carbonate system.This,in turn,affects the physiological processes of phytoplankton.In response to increas...Ocean acidification(OA),caused by the rising concentration of atmospheric CO_(2),leads to changes in the marine carbonate system.This,in turn,affects the physiological processes of phytoplankton.In response to increased pCO_(2) levels,marine microalgae modulate their physiological responses to meet their energy and metabolic requirements.Nitrogen metabolism is a critical metabolic pathway,directly affecting the growth and reproductive capacity of marine microorganisms.Understanding the molecular mechanisms that regulate nitrogen metabolism in microalgae under OA conditions is therefore crucial.This study aimed to investi-gate how OA affects the expression profiles of key genes in the nitrogen metabolic pathway of the marine diatom Skeletonema costatum.Our findings indicate that OA upregulates key genes involved in the nitrogen metabolic pathway,specifically those related to nitrate assimilation and glutamate metabolism.Moreover,pCO_(2) has been identified as the predominant factor affecting the expression of these genes,with a more significant impact than pH variations in S.costatum.This research not only advances our understanding of the adaptive mechanisms of S.costatum in response to OA but also provides essential data for predicting the ecological consequences of OA on marine diatoms.展开更多
Although the adverse impacts of ocean acidification(OA)on marine calcifiers have been investigated extensively,the anti-stress capabilities regulated by increased light availability are unclear.Herein,the interactive ...Although the adverse impacts of ocean acidification(OA)on marine calcifiers have been investigated extensively,the anti-stress capabilities regulated by increased light availability are unclear.Herein,the interactive effects of three light levels(30μmol photons/(m^(2)·s),150μmol photons/(m^(2)·s),and 240μmol photons/(m^(2)·s)combined with two pCO_(2)concentrations(400 ppmv and 1400 ppmv)on the physiological acclimation of the calcifying macroalga Halimeda opuntia were investigated using a pCO_(2)-light coupling experiment.The OA negatively influenced algal growth,calcification,photosynthesis,and other physiological performances in H.opuntia.The relative growth rate under elevated pCO_(2)conditions significantly declined by 13.14%−41.29%,whereas net calcification rates decreased by nearly three-fold under OA conditions.Notably,increased light availability enhanced stress resistance through the accumulation of soluble organic molecules,especially soluble carbohydrate,soluble protein,and free amino acids,and in combination with metabolic enzyme-driven activities,OA stress was alleviated.The carotenoid content under low light conditions increased markedly,and the rapid light curve of the relative electron transport rate was enhanced significantly by increasing light intensities,indicating that this new organization of the photosynthetic machinery in H.opuntia accommodated light variations and elevated pCO_(2)conditions.Thus,the enhanced metabolic performance of the calcifying macroalga H.opuntia mitigated OA-related stress.展开更多
Environmental changes,such as ocean acidification and eutrophication,have created threats to kelp mariculture.In this study,the growth,photosynthesis,respiration and nutrient composition of Saccharina japonica were ev...Environmental changes,such as ocean acidification and eutrophication,have created threats to kelp mariculture.In this study,the growth,photosynthesis,respiration and nutrient composition of Saccharina japonica were evaluated at different levels of pCO2(400 and 800μL L−1)and nutrients(nutrient-enriched and non-enriched seawater).Elevated pCO2 decreased the relative growth rate(RGR),net photosynthetic rate and contents of tissue carbon and tissue nitrogen under non-enriched nutrient conditions,but it had no significant effect on these parameters under nutrient-enriched conditions.The dark respiration rate was positively affected by elevated pCO2 regardless of the nutrient conditions.However,the C:N was unaffected by elevated pCO2 at both nutrient levels.These results implied that ocean acidification could reduce the production and nutrient contents in the tissues of S.japonica,which was associated with nutrient conditions.展开更多
Ocean acidification and eutrophication are two important environmental stressors.They inevitably impact marine macroalgae,and hence the coastal ecosystem of China.Saccharina japonica,as the main culture species in Chi...Ocean acidification and eutrophication are two important environmental stressors.They inevitably impact marine macroalgae,and hence the coastal ecosystem of China.Saccharina japonica,as the main culture species in China,is suffering the harmful golden tide caused by Sargassum horneri.However,it remains unclear whether the detrimental effects of S.horneri on S.japonica cultivation become more severe in future acidified and eutrophic scenario.In this study,we respectively investigated the effects of pCO_(2)(400μatm and 1000μatm)and nutrients(non-enriched and enriched seawater)on the growth,photosynthesis,respiration,chlorophyll contents,and tissue nitrogen of S.japonica and S.horneri.Results indicated that enrichment of nutrients contributed S.horneri to utilize HCO_(3)^(−).The carbon acquisition pathway shifted from HCO_(3)^(−)to CO_(2) in S.japonica,while S.horneri re-mained using HCO_(3)^(−)regulated by nutrient enrichment.S.horneri exhibited better photosynthetic traits than S.japonica,with a higher level of net photosynthetic rate and chlorophyll contents at elevated pCO_(2) and enriched nutrients.Tissue nitrogen also accumulated richly in the thalli of S.horneri under higher pCO_(2) and nutrients.Significant enhancement in growth was only detected in S.horneri under synergistic stress.Together,S.horneri showed competitive dominance in current study.These findings suggest that increasing risk of golden tide in acidified and eutrophic ocean can most likely result in great damage to S.japonica cultivation.展开更多
The global effects of ocean acidification (OA) on coral reefs are of growing concern. Carbon dioxide released into the atmosphere as a result of burning fossil fuels, not only has an effect on “global warming”, but ...The global effects of ocean acidification (OA) on coral reefs are of growing concern. Carbon dioxide released into the atmosphere as a result of burning fossil fuels, not only has an effect on “global warming”, but also on OA which is called the “other CO2 problem”. OA combined with high ocean temperatures has resulted in a massive bleaching of coral reefs in the Indian Ocean and throughout Southeast Asia over the past decade, which is ultimately lethal. Here we discuss the option if innovative seaweed bio-technology—the Ulva lactuca bioreactor option, with its H+ ion-absorbing capacity and its huge green biomass production of around 50 MT/ha/year—which can stabilize our “World Ocean” and our global coral reefs. From our calculations, we came to the conclusion that an area covered with “Ulva lactuca bioreactors” with a production capacity of 250 × 1016 ha of seaweed per year is needed to remove all H+ ions that cause OA in our “World Ocean” since the beginning of the “Industrial Revolution” ≈ 250 years ago. This is a daunting task and therefore we have opted for a multi-faceted approach including variability in seaweed species, avoidance of eutrophication & heavy-metal accumulation, prevention of global warming by more green-biomass production and a better estimation of the huge Kelp seaweed populations in temperate zones in order to protect our coral reefs for the short term.展开更多
Using the UVic Earth System Model, this study simulated the change of seawater chemistry and analyzed the chemical habitat surrounding shallow- and cold-water coral reefs from the year 1800 to 2300 employing RCP2.6, R...Using the UVic Earth System Model, this study simulated the change of seawater chemistry and analyzed the chemical habitat surrounding shallow- and cold-water coral reefs from the year 1800 to 2300 employing RCP2.6, RCP4.5, RCP6.0, and RCP8.5 scenarios. The model results showed that the global ocean will continue to absorb atmospheric CO2. Global mean surface ocean temperature will rise 1.1-2.8 K at the end of the 21st century across RCP scenarios. Meanwhile, the global mean surface ocean pH will drop 0.14--0.42 and the ocean surface mean con- centration of carbonate will decrease 20%--51% across the RCP scenarios. The saturated state of sea water with respect to calcite carbonate minerals （t2） will decrease rapidly. During the pre-industrial period, 99% of the shallow-water coral reefs were surrounded by seawater with t2 〉 3.5 and 87% of the deep-sea coral reefs were surrounded by seawater with aragonite supersaturation. Within the 21st century, except for the high mitigation scenario of RCP2.6, almost none shallow-water coral reefs will be surrounded by seawater with g2 〉 3.5. Under the intensive emission scenario of RCP8.5, by the year 2100, the aragonite saturation horizon will rise to 308 m under the sea surface from 1138 m at the pre- industrial period, thus 73% of the cold-water coral reefs will be surrounded by seawater with aragonite undersaturation. By the year 2300, only 5% of the cold-water coral reefs will be surrounded by seawater with aragonite supersaturation.展开更多
Due to the elevated atmospheric carbon dioxide, ocean acidification(OA) has recently emerged as a research theme in marine biology due to an expected deleterious effect of altered seawater chemistry on calcification. ...Due to the elevated atmospheric carbon dioxide, ocean acidification(OA) has recently emerged as a research theme in marine biology due to an expected deleterious effect of altered seawater chemistry on calcification. A system simulating future OA scenario is crucial for OA-related studies. Here, we designed an OA-simulated system(OASys) with three solenoid-controlled CO_2 gas channels. The OASys can adjust the pH of the seawater by bubbling CO_2 gas into seawaters via feedback systems. The OASys is very simple in structure with an integrated design and is new-user friendly with the instruction. Moreover, the OASys can monitor and record real-time pH values and can maintain pH levels within 0.02 pH unit. In a 15-d experiment, the OASys was applied to simulate OA in which the expected target pH values were 8.00, 7.80 and 7.60 to study the calcifying response of Galaxea fascicularis. The results showed daily mean seawater pH values held at pH 8.00±0.01, 7.80±0.01 and 7.61±0.01 over15 d. Correspondingly, the coral calcification of G. fascicularis gradually decreased with reduced pH.展开更多
We evaluated the effect of pH on larval development in larval Pacific oyster(Crassostrea gigas) and blood cockle(Arca inflata Reeve).The larvae were reared at pH 8.2(control),7.9,7.6,or 7.3beginning 30 min or 24 h pos...We evaluated the effect of pH on larval development in larval Pacific oyster(Crassostrea gigas) and blood cockle(Arca inflata Reeve).The larvae were reared at pH 8.2(control),7.9,7.6,or 7.3beginning 30 min or 24 h post fertilization.Exposure to lower pH during early embryonic development inhibited larval shell formation in both species.Compared with the control,larvae took longer to reach the D-veliger stage when reared under pH 7.6 and 7.3.Exposure to lower pH immediately after fertilization resulted in significantly delayed shell formation in the Pacific oyster larvae at pH 7.3 and blood cockle larvae at pH 7.6 and 7.3.However,when exposure was delayed until 24 h post fertilization,shell formation was only inhibited in blood cockle larvae reared at pH 7.3.Thus,the early embryonic stages were more sensitive to acidified conditions.Our results suggest that ocean acidification will have an adverse effect on embryonic development in bivalves.Although the effects appear subtle,they may accumulate and lead to subsequent issues during later larval development.展开更多
Ocean acidifi cation(OA)and global warming-induced water column stratification can signifi cantly alter phytoplankton-related biological activity in the marine ecosystem.Yet how these changes may play out in the tropi...Ocean acidifi cation(OA)and global warming-induced water column stratification can signifi cantly alter phytoplankton-related biological activity in the marine ecosystem.Yet how these changes may play out in the tropical Indian Ocean remains unclear.This study investigated the ecological and metabolic responses of the different phytoplankton functional groups to elevated CO_(2) partial pressure and nitrate deficiency in two different environments of the eastern Indian Ocean(EIO).It is revealed that phytoplankton growth and metabolic rates are more sensitive to inorganic nutrients rather than CO_(2).The combined interactive effects of OA and N-limitation on phytoplankton populations are functional groupspecific.In particular,the abundance and calcification rate of calcifying coccolithophores are expected to be enhanced in the future EIO.The underlying mechanisms for this enhancement may be ascribed to coccolithophore’s lower carbon concentrating mechanisms(CCMs)efficiency and OA-induced[HCO^(-)_(3)]increase.In comparison,the abundance of non-calcifying microphytoplankton(e.g.,diatoms and dinoflagellates)and primary productivity would be inhibited under those conditions.Diff erent from previous laboratory experiments,interspecifi c competition for resources would be an important consideration in the natural phytoplankton populations.These combined factors would roughly determine calcifying coccolithophores as“winners”and non-calcifying microphytoplankton as“losers”in the future ocean scenario.Due to the large species-specific differences in phytoplankton sensitivity to OA,comprehensive investigations on oceanic phytoplankton communities are essential to precisely predict phytoplankton ecophysiological response to ocean acidification.展开更多
Objective The end-Triassic mass extinction was one of the five most profound Phanerozoic extinction events.This event was accompanied by a series of significant environmental changes,of which the most notable is the e...Objective The end-Triassic mass extinction was one of the five most profound Phanerozoic extinction events.This event was accompanied by a series of significant environmental changes,of which the most notable is the emergence of warm climate and the world-wide disappearance of carbonate platform.展开更多
The present study was conducted to determine the effects of elevated pCO2 on growth, photosynthesis, dark respiration and inorganic carbon acquisition in the marine microalga Dunaliella salina. To accomplish this, D. ...The present study was conducted to determine the effects of elevated pCO2 on growth, photosynthesis, dark respiration and inorganic carbon acquisition in the marine microalga Dunaliella salina. To accomplish this, D. salina was incubated in semi-continuous cultures under present-day CO2 levels （390 μatm, PHNBs： 8.10）, predicted year 2100 CO2 levels （1000 μatm, pHNBs： 7.78） and predicted year 2300 CO2 levels （2 000μatm, PHNBS： 7.49）. Elevated pCO2 significantly enhanced photosynthesis （in terms of gross photosynthetic O2 evolution, effective quantum yield （△F/F＇m）, photosynthetic efficiency （a）, maximum relative electron transport rate （rETRmax） and ribulose-1,5-bisphosphate carboxylase/ oxygenase （Rubiseo） activity） and dark respiration olD. salina, but had insignificant effects on growth. The photosynthetic 02 evolution olD. salina was significantly inhibited by the inhibitors acetazolamide （△Z）, ethoxyzolamide （EZ） and 4,4＇-diisothiocyanostilbene-2,2＇-disulfonate （DIDS）, indicating that D. salina is capable of acquiring HCO3 via extracellular carbonic anhydrase and anion-exchange proteins. Furthermore, the lower inhibition of the photosynthetic O2 evolution at high pCO2 levels by AZ, EZ and DIDS and the decreased carbonic anhydrase showed that carbon concentrating mechanisms were down-regulated at high pCO2. In conclusion, our results show that photosynthesis, dark respiration and CCMs will be affected by the increased pCO2/low pH conditions predicted for the future, but that the responses olD. salina to high pCO2/low pH might be modulated by other environmental factors such as light, nutrients and temperature. Therefore, further studies are needed to determine the interactive effects ofpCO2, temperature, light and nutrients on marine microalgae.展开更多
Over the past decades, the Arctic Ocean has experienced rapid warming under climate change, which has dramatically altered its physical and biogeochemical properties. Reduction in the sea-ice cover is one of the most ...Over the past decades, the Arctic Ocean has experienced rapid warming under climate change, which has dramatically altered its physical and biogeochemical properties. Reduction in the sea-ice cover is one of the most important driving forces of biogeochemical changes in the Arctic Ocean. Between 1999 and 2016, seven Chinese National Arctic Research Expeditions have taken place in the Bering and Chukchi seas, allowing assessment of the biogeochemical response of the western Arctic Ocean to global warming. Herein, we summarize advances in Chinese and international marine biogeochemistry research in the western Arctic Ocean, reviewing results from the Chinese expeditions and highlighting future trends of biogeochemistry in the Pacific Arctic region. The findings reported in this paper contribute towards a better understanding of water masses, greenhouse gases, nutrients, ocean acidification, and organic carbon export and burial processes in this region.展开更多
By the end of the 21st century, mean sea surface temperatures are expected to increase 4?C, while atmospheric CO2 concentrations are predicted to triple causing seawater to become acidic. These compounding effects wil...By the end of the 21st century, mean sea surface temperatures are expected to increase 4?C, while atmospheric CO2 concentrations are predicted to triple causing seawater to become acidic. These compounding effects will undoubtedly have major consequences for the organisms and processes in the oceans. Bacterioplankton play a vital role in the marine carbon cycle and the oceans’ ability to sequester CO2. We utilized pCO2 perturbation experiments to investigate the effects of ocean acidity and elevated temperature on bacterioplankton community structure and metabolism. Terminal-restriction fragment length polymorphism (T-RFLP) of small subunit ribosomal (SSU) genes revealed that bacterioplankton incubated in lower pH conditions exhibited a reduction of species richness, evenness, and overall diversity, relative to those incubated in ambient pH conditions. Non-metric multidimensional scaling (MDS) of T-RFLP data resulted in clustering by pH suggesting that pH influenced the structure of these communities. Shifts in the dominant members of bacterioplankton communities incubated under different pH were observed in both T-RFLP and SSU clone library analyses. Both ambient and low pH communities were dominated by Gammaproteobacteria and Alphaproteobacteria, although abundance of Alphaproteobacteria increased in communities incubated at lower pH. This was expressed by the gamma to alpha ratio dropping from ~9 to 4, respectively. In general, the representative taxa from these two classes were distinctly different between the treatments, with a few taxa found to be persistent in both treatments. Changes in the structure of bacterioplankton communities coincided with significant changes to their overall metabolism. Bacterial production rates decreased, while bacterial respiration increased under lower pH conditions. This study highlights the ability of bacterioplankton communities to respond to ocean acidification both structurally and metabolically, which may have significant implications for their ecological function in the marine carbon cycle and the ocean’s response to global climate change.展开更多
Solar radiation modification(SRM,also termed as geoengineering)has been proposed as a potential option to counteract anthropogenic warming.The underlying idea of SRM is to reduce the amount of sunlight reaching the at...Solar radiation modification(SRM,also termed as geoengineering)has been proposed as a potential option to counteract anthropogenic warming.The underlying idea of SRM is to reduce the amount of sunlight reaching the atmosphere and surface,thus offsetting some amount of global warming.Here,the authors use an Earth system model to investigate the impact of SRM on the global carbon cycle and ocean biogeochemistry.The authors simulate the temporal evolution of global climate and the carbon cycle from the pre-industrial period to the end of this century under three scenarios:the RCP4.5 CO_(2) emission pathway,the RCP8.5 CO_(2) emission pathway,and the RCP8.5 CO_(2) emission pathway with the implementation of SRM to maintain the global mean surface temperature at the level of RCP4.5.The simulations show that SRM,by altering global climate,also affects the global carbon cycle.Compared to the RCP8.5 simulation without SRM,by the year 2100,SRM reduces atmospheric CO_(2) by 65 ppm mainly as a result of increased CO_(2) uptake by the terrestrial biosphere.However,SRM-induced change in atmospheric CO_(2) and climate has a small effect in mitigating ocean acidification.By the year 2100,relative to RCP8.5,SRM causes a decrease in surface ocean hydrogen ion concentration([H^(+)])by 6% and attenuates the seasonal amplitude of[H^(+)]by about 10%.The simulations also show that SRM has a small effect on globally integrated ocean net primary productivity relative to the high-CO_(2) simulation without SRM.This study contributes to a comprehensive assessment of the effects of SRM on both the physical climate and the global carbon cycle.展开更多
Ocean acidification(OA)affects marine biodiversity and alters the structure and function of marine populations,communities,and ecosystems.Recently,effects of OA on the behavioral responses of marine animals have been ...Ocean acidification(OA)affects marine biodiversity and alters the structure and function of marine populations,communities,and ecosystems.Recently,effects of OA on the behavioral responses of marine animals have been given with much attention.While many of previous studies focuses on marine fish.Evidence suggests that marine invertebrate behaviors were also be affected.In this review,we discussed the effects of CO2-driven OA on the most common behaviors studied in marine invertebrates,including settlement and habitat selection,feeding,anti-predatory,and swimming behaviors,and explored the related mechanisms behind behaviors.This review summarizes how OA affects marine invertebrate behavior,and provides new insights and highlights novel areas for future research.展开更多
The problem of ocean acidification caused by the increase of atmospheric carbon dioxide concentration is becoming increasingly prominent.Field observation in the northwest Pacific Ocean was carried out along the 150&#...The problem of ocean acidification caused by the increase of atmospheric carbon dioxide concentration is becoming increasingly prominent.Field observation in the northwest Pacific Ocean was carried out along the 150°E transect in November 2019.The distribution characteristics and influencing factors of the surface seawater carbonate chemistry,including dissolved inorganic carbon(DIC),total alkalinity(TA),pH,partial pressure of carbon dioxide(pCO_(2))and aragonite saturation state(Ω_(arag))were investigated.DIC and TA ranged from 1915 to 2014μmol kg^(−1)and 2243 to 2291μmol kg^(−1),respectively;DIC in general decreased with decreasing latitude,but TA had no clear latitudinal gradient.pCO_(2)values increased with the decrease of latitude and were all below the atmospheric pCO_(2)level,ranging from 332 to 387μatm.pH on the total hydrogen ion concentration scale(pH_(T))decreased with the decrease of latitude in the range of 8.044–8.110,whileΩ_(arag) increased with the decrease of latitude in the range of 2.61–3.88,suggesting that the spatial distributions of pH_(T) andΩ_(arag) were out of phase.Compared with the present,the predicted values of pH_(T) and Ω_(arag) by the end of this century would decrease remarkedly;larger declines were found in the higher pH_(T) and Ω_(arag) regions,resulting in the differences along the meridional gradient becoming smaller for bothpH_(T) and Ω_(arag).展开更多
Although the impact of ocean acidification on marine bivalves has been previously investigated under mainly controlled laboratory conditions,it is still unclear whether the impact of acidification on sediment-burrowin...Although the impact of ocean acidification on marine bivalves has been previously investigated under mainly controlled laboratory conditions,it is still unclear whether the impact of acidification on sediment-burrowing species differs between those within or without sediment.In order to fill this gap in our knowledge,we compared shell properties of the infaunal Manila clam(Ruditapes philippinarum)exposed to three pH concentrations(7.4,7.7,and 8.0),within and without sediments.In the first experiment(140 d),clams were exposed to seawater in an acidification system without sediment.A decrease in shell weight corresponding to the increase in dissolution rate was observed in the group ofpH 7.4,at which shell color disappeared or whitened.SEM observations confirmed the changes of the external shell surface.In the second experiment(170 d),sediment was placed at the bottom of each exposure chamber.The effects were found obvious in shell dissolution rate and shell color in the shell specimens exposed to overlying seawater but not found in the shell specimens exposed to sediment.Although the experimental period was longer in the second experiment,shell specimens in the first experiment were more seriously damaged than those in the second experiment under acidic seawater conditions.Our results,in relation to the defense function of the shell,show that marine bivalves in burrowing behavior are more adaptable to seawater acidification than those who do not burrow into sediment.展开更多
基金Supported by National Natural Science Foundation of China (No.41006090)the Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX2-YW-Q07-03)the National High Technology Research and Development Program of China (863 Program) (No.2006AA10A409)
文摘Oceanic uptake of anthropogenic carbon dioxide results in a decrease in seawater pH, a process known as "ocean acidification". The pearl oyster Pinctada fucata, the noble scallop Chlamys nobilis, and the green-lipped mussel Perna viridis are species of economic and ecological importance along the southern coast of China. We evaluated the effects of seawater acidification on clearance, respiration, and excretion rates in these three species. The animals were reared in seawater at pH 8.1 (control), 7.7, or 7.4. The clearance rate was highest at pH 7.7 for P. fucata and at pH 8.1 for C. nobilis and P. viridis. The pH had little effecton the respiration rate of P. fucata and P. viridis. In contrast, the respiration rate was significantly lower atpH 7.4 in C. nobilis. The excretion rate was significantly lower at pH 7.4 than pH 8.1 for all species. Theresults indicate that the reduction in seawater pH likely affected the metabolic process (food intake, oxygenconsumption, and ammonia excretion) of these bivalves. Different species respond differently to seawateracidification. Further studies are needed to demonstrate the exact mechanisms for this effect and evaluateadaptability of these bivalves to future acidified oceans.
基金funded by the Ministry of Agriculture of the People’s Republic of China (No.CARS-49)。
文摘With the rapid development of oil,energy,power and other industries,CO_(2) emissions rise sharply,which will cause a large amount of CO_(2) in the air be absorbed by the ocean and lead to ocean acidification.The growth and development of organisms can be seriously affected by acidified seawater.Sepia esculenta is a mollusk with high nutritional and economic value and is widely cultured in offshore waters of China.Larvae are the early life forms of the organism and are more vulnerable to changes in the external environment.Too low pH will lead to some adverse reactions in larvae,which will affect metabolism,immune response and other life activities.In this study,we sequenced the transcriptome of S.esculenta subjected to acidified seawater stress and identified 1072differentially expressed genes(DEGs).The detected atypical expression of DEGs substantiates cellular malformation and translocation in S.esculenta under low pH stimulation.Simultaneously,this also substantiates the notable impact of ocean acidification on mollusks.These DEGs were used for functional enrichment analysis of GO and KEGG,and the top twenty items of the biological process classification in GO terms and 11 KEGG signaling pathways were significantly enriched.Finally,the constructed proteinprotein interaction network(PPI)was used to analyze protein-protein interactions,and 12 key DEGs and 3 hub genes were identified.The reliability of 12 genes was verified by quantitative RT-PCR.A comprehensive analysis of the KEGG signaling pathway and PPI revealed that ocean acidification leads to abnormalities in lipid metabolism in S.esculenta larvae,which can lead to cancer development and metastasis,accompanied by some degree of inflammation.The results of the study will help to further investigate the physiological processes of S.esculenta when stimulated by ocean acidification,and provide a reference to cope with the captive breeding of S.esculenta affected by acidification.
基金supported by the Scientific and Technological Innovation Project of the Laoshan Laboratory(No.LSKJ202203700)the National Key Research and Development Program of China(No.2022YFC3105202)the National Natural Science Foundation of China(No.41976133).
文摘Ocean acidification(OA),caused by the rising concentration of atmospheric CO_(2),leads to changes in the marine carbonate system.This,in turn,affects the physiological processes of phytoplankton.In response to increased pCO_(2) levels,marine microalgae modulate their physiological responses to meet their energy and metabolic requirements.Nitrogen metabolism is a critical metabolic pathway,directly affecting the growth and reproductive capacity of marine microorganisms.Understanding the molecular mechanisms that regulate nitrogen metabolism in microalgae under OA conditions is therefore crucial.This study aimed to investi-gate how OA affects the expression profiles of key genes in the nitrogen metabolic pathway of the marine diatom Skeletonema costatum.Our findings indicate that OA upregulates key genes involved in the nitrogen metabolic pathway,specifically those related to nitrate assimilation and glutamate metabolism.Moreover,pCO_(2) has been identified as the predominant factor affecting the expression of these genes,with a more significant impact than pH variations in S.costatum.This research not only advances our understanding of the adaptive mechanisms of S.costatum in response to OA but also provides essential data for predicting the ecological consequences of OA on marine diatoms.
基金The National Natural Science Foundation of China under contract No.42006129the Guangzhou Science and Technology Project under contract No.202102021228+2 种基金the National Key Research and Development Project of China under contract No.2021YFC3100500the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)under contract No.GML2019ZD0404the Special Research Assistant Grant Program of the Chinese Academy of Sciences.
文摘Although the adverse impacts of ocean acidification(OA)on marine calcifiers have been investigated extensively,the anti-stress capabilities regulated by increased light availability are unclear.Herein,the interactive effects of three light levels(30μmol photons/(m^(2)·s),150μmol photons/(m^(2)·s),and 240μmol photons/(m^(2)·s)combined with two pCO_(2)concentrations(400 ppmv and 1400 ppmv)on the physiological acclimation of the calcifying macroalga Halimeda opuntia were investigated using a pCO_(2)-light coupling experiment.The OA negatively influenced algal growth,calcification,photosynthesis,and other physiological performances in H.opuntia.The relative growth rate under elevated pCO_(2)conditions significantly declined by 13.14%−41.29%,whereas net calcification rates decreased by nearly three-fold under OA conditions.Notably,increased light availability enhanced stress resistance through the accumulation of soluble organic molecules,especially soluble carbohydrate,soluble protein,and free amino acids,and in combination with metabolic enzyme-driven activities,OA stress was alleviated.The carotenoid content under low light conditions increased markedly,and the rapid light curve of the relative electron transport rate was enhanced significantly by increasing light intensities,indicating that this new organization of the photosynthetic machinery in H.opuntia accommodated light variations and elevated pCO_(2)conditions.Thus,the enhanced metabolic performance of the calcifying macroalga H.opuntia mitigated OA-related stress.
基金Ocean University of China in 2018 and the Major Scientific and Technological Innovation Project of Shandong Provincial Key Research and Development Program(No.2019JZZY020708).
文摘Environmental changes,such as ocean acidification and eutrophication,have created threats to kelp mariculture.In this study,the growth,photosynthesis,respiration and nutrient composition of Saccharina japonica were evaluated at different levels of pCO2(400 and 800μL L−1)and nutrients(nutrient-enriched and non-enriched seawater).Elevated pCO2 decreased the relative growth rate(RGR),net photosynthetic rate and contents of tissue carbon and tissue nitrogen under non-enriched nutrient conditions,but it had no significant effect on these parameters under nutrient-enriched conditions.The dark respiration rate was positively affected by elevated pCO2 regardless of the nutrient conditions.However,the C:N was unaffected by elevated pCO2 at both nutrient levels.These results implied that ocean acidification could reduce the production and nutrient contents in the tissues of S.japonica,which was associated with nutrient conditions.
基金This work is funded by the Major Scientific and Technological Innovation Project of Shandong Provincial Key Research and Development Program(No.2019JZZY020708).
文摘Ocean acidification and eutrophication are two important environmental stressors.They inevitably impact marine macroalgae,and hence the coastal ecosystem of China.Saccharina japonica,as the main culture species in China,is suffering the harmful golden tide caused by Sargassum horneri.However,it remains unclear whether the detrimental effects of S.horneri on S.japonica cultivation become more severe in future acidified and eutrophic scenario.In this study,we respectively investigated the effects of pCO_(2)(400μatm and 1000μatm)and nutrients(non-enriched and enriched seawater)on the growth,photosynthesis,respiration,chlorophyll contents,and tissue nitrogen of S.japonica and S.horneri.Results indicated that enrichment of nutrients contributed S.horneri to utilize HCO_(3)^(−).The carbon acquisition pathway shifted from HCO_(3)^(−)to CO_(2) in S.japonica,while S.horneri re-mained using HCO_(3)^(−)regulated by nutrient enrichment.S.horneri exhibited better photosynthetic traits than S.japonica,with a higher level of net photosynthetic rate and chlorophyll contents at elevated pCO_(2) and enriched nutrients.Tissue nitrogen also accumulated richly in the thalli of S.horneri under higher pCO_(2) and nutrients.Significant enhancement in growth was only detected in S.horneri under synergistic stress.Together,S.horneri showed competitive dominance in current study.These findings suggest that increasing risk of golden tide in acidified and eutrophic ocean can most likely result in great damage to S.japonica cultivation.
文摘The global effects of ocean acidification (OA) on coral reefs are of growing concern. Carbon dioxide released into the atmosphere as a result of burning fossil fuels, not only has an effect on “global warming”, but also on OA which is called the “other CO2 problem”. OA combined with high ocean temperatures has resulted in a massive bleaching of coral reefs in the Indian Ocean and throughout Southeast Asia over the past decade, which is ultimately lethal. Here we discuss the option if innovative seaweed bio-technology—the Ulva lactuca bioreactor option, with its H+ ion-absorbing capacity and its huge green biomass production of around 50 MT/ha/year—which can stabilize our “World Ocean” and our global coral reefs. From our calculations, we came to the conclusion that an area covered with “Ulva lactuca bioreactors” with a production capacity of 250 × 1016 ha of seaweed per year is needed to remove all H+ ions that cause OA in our “World Ocean” since the beginning of the “Industrial Revolution” ≈ 250 years ago. This is a daunting task and therefore we have opted for a multi-faceted approach including variability in seaweed species, avoidance of eutrophication & heavy-metal accumulation, prevention of global warming by more green-biomass production and a better estimation of the huge Kelp seaweed populations in temperate zones in order to protect our coral reefs for the short term.
基金supported by National Natural Science Foundation of China(41276073,41422503)National Key Basic Research Program of China(2015CB953601)+1 种基金Zhejiang University K.P.Chao's High Technology Development Foundationthe Fundamental Research Funds for the Central Universities
文摘Using the UVic Earth System Model, this study simulated the change of seawater chemistry and analyzed the chemical habitat surrounding shallow- and cold-water coral reefs from the year 1800 to 2300 employing RCP2.6, RCP4.5, RCP6.0, and RCP8.5 scenarios. The model results showed that the global ocean will continue to absorb atmospheric CO2. Global mean surface ocean temperature will rise 1.1-2.8 K at the end of the 21st century across RCP scenarios. Meanwhile, the global mean surface ocean pH will drop 0.14--0.42 and the ocean surface mean con- centration of carbonate will decrease 20%--51% across the RCP scenarios. The saturated state of sea water with respect to calcite carbonate minerals （t2） will decrease rapidly. During the pre-industrial period, 99% of the shallow-water coral reefs were surrounded by seawater with t2 〉 3.5 and 87% of the deep-sea coral reefs were surrounded by seawater with aragonite supersaturation. Within the 21st century, except for the high mitigation scenario of RCP2.6, almost none shallow-water coral reefs will be surrounded by seawater with g2 〉 3.5. Under the intensive emission scenario of RCP8.5, by the year 2100, the aragonite saturation horizon will rise to 308 m under the sea surface from 1138 m at the pre- industrial period, thus 73% of the cold-water coral reefs will be surrounded by seawater with aragonite undersaturation. By the year 2300, only 5% of the cold-water coral reefs will be surrounded by seawater with aragonite supersaturation.
基金The China-ASEAN Maritime Cooperation Fund Project "China-ASEAN Countries Collaboration on Marine Endangered Species Researches" and "China-ASEAN Marine Protected Areas Ecosystem Management Network"Regional Demonstration of Marine Economy Innovative Development Project under contract No.16PZY002SF18+1 种基金the China-Indonesia Maritime Cooperation Fund Project "China-Indonesia Bitung Ecological Station Establishment"the National Natural Science Foundation of China under contract No.41506123
文摘Due to the elevated atmospheric carbon dioxide, ocean acidification(OA) has recently emerged as a research theme in marine biology due to an expected deleterious effect of altered seawater chemistry on calcification. A system simulating future OA scenario is crucial for OA-related studies. Here, we designed an OA-simulated system(OASys) with three solenoid-controlled CO_2 gas channels. The OASys can adjust the pH of the seawater by bubbling CO_2 gas into seawaters via feedback systems. The OASys is very simple in structure with an integrated design and is new-user friendly with the instruction. Moreover, the OASys can monitor and record real-time pH values and can maintain pH levels within 0.02 pH unit. In a 15-d experiment, the OASys was applied to simulate OA in which the expected target pH values were 8.00, 7.80 and 7.60 to study the calcifying response of Galaxea fascicularis. The results showed daily mean seawater pH values held at pH 8.00±0.01, 7.80±0.01 and 7.61±0.01 over15 d. Correspondingly, the coral calcification of G. fascicularis gradually decreased with reduced pH.
基金Supported by the Special Scientific Research Funds for Central Non-Profit Institutes,CAFS(No.2014A01 YYOl)the National Basic Research Program of China(973 Program)(No.2011CB409805)+1 种基金the Earmarked Fund for Modern Agro-Industry Technology Research System(No.CARS-48)the National Key Technology R&D Program of China(No.2011BAD45B01)
文摘We evaluated the effect of pH on larval development in larval Pacific oyster(Crassostrea gigas) and blood cockle(Arca inflata Reeve).The larvae were reared at pH 8.2(control),7.9,7.6,or 7.3beginning 30 min or 24 h post fertilization.Exposure to lower pH during early embryonic development inhibited larval shell formation in both species.Compared with the control,larvae took longer to reach the D-veliger stage when reared under pH 7.6 and 7.3.Exposure to lower pH immediately after fertilization resulted in significantly delayed shell formation in the Pacific oyster larvae at pH 7.3 and blood cockle larvae at pH 7.6 and 7.3.However,when exposure was delayed until 24 h post fertilization,shell formation was only inhibited in blood cockle larvae reared at pH 7.3.Thus,the early embryonic stages were more sensitive to acidified conditions.Our results suggest that ocean acidification will have an adverse effect on embryonic development in bivalves.Although the effects appear subtle,they may accumulate and lead to subsequent issues during later larval development.
基金Supported by the National Natural Science Foundation of China(Nos.41876134,41676112,41276124,41706184)the Changjiang Scholar Program of Chinese Ministry of Education of China(No.T2014253)to Jun SUN。
文摘Ocean acidifi cation(OA)and global warming-induced water column stratification can signifi cantly alter phytoplankton-related biological activity in the marine ecosystem.Yet how these changes may play out in the tropical Indian Ocean remains unclear.This study investigated the ecological and metabolic responses of the different phytoplankton functional groups to elevated CO_(2) partial pressure and nitrate deficiency in two different environments of the eastern Indian Ocean(EIO).It is revealed that phytoplankton growth and metabolic rates are more sensitive to inorganic nutrients rather than CO_(2).The combined interactive effects of OA and N-limitation on phytoplankton populations are functional groupspecific.In particular,the abundance and calcification rate of calcifying coccolithophores are expected to be enhanced in the future EIO.The underlying mechanisms for this enhancement may be ascribed to coccolithophore’s lower carbon concentrating mechanisms(CCMs)efficiency and OA-induced[HCO^(-)_(3)]increase.In comparison,the abundance of non-calcifying microphytoplankton(e.g.,diatoms and dinoflagellates)and primary productivity would be inhibited under those conditions.Diff erent from previous laboratory experiments,interspecifi c competition for resources would be an important consideration in the natural phytoplankton populations.These combined factors would roughly determine calcifying coccolithophores as“winners”and non-calcifying microphytoplankton as“losers”in the future ocean scenario.Due to the large species-specific differences in phytoplankton sensitivity to OA,comprehensive investigations on oceanic phytoplankton communities are essential to precisely predict phytoplankton ecophysiological response to ocean acidification.
基金financially supported by the National Science Foundation of China(grant No.41572089)
文摘Objective The end-Triassic mass extinction was one of the five most profound Phanerozoic extinction events.This event was accompanied by a series of significant environmental changes,of which the most notable is the emergence of warm climate and the world-wide disappearance of carbonate platform.
基金Supported by the Joint Funds of the National Natural Science Foundation of China and the Marine Science Research Center of the People’s Government of Shandong Province(No.U1406403)the National Natural Science Foundation of China(No.41476091)
文摘The present study was conducted to determine the effects of elevated pCO2 on growth, photosynthesis, dark respiration and inorganic carbon acquisition in the marine microalga Dunaliella salina. To accomplish this, D. salina was incubated in semi-continuous cultures under present-day CO2 levels （390 μatm, PHNBs： 8.10）, predicted year 2100 CO2 levels （1000 μatm, pHNBs： 7.78） and predicted year 2300 CO2 levels （2 000μatm, PHNBS： 7.49）. Elevated pCO2 significantly enhanced photosynthesis （in terms of gross photosynthetic O2 evolution, effective quantum yield （△F/F＇m）, photosynthetic efficiency （a）, maximum relative electron transport rate （rETRmax） and ribulose-1,5-bisphosphate carboxylase/ oxygenase （Rubiseo） activity） and dark respiration olD. salina, but had insignificant effects on growth. The photosynthetic 02 evolution olD. salina was significantly inhibited by the inhibitors acetazolamide （△Z）, ethoxyzolamide （EZ） and 4,4＇-diisothiocyanostilbene-2,2＇-disulfonate （DIDS）, indicating that D. salina is capable of acquiring HCO3 via extracellular carbonic anhydrase and anion-exchange proteins. Furthermore, the lower inhibition of the photosynthetic O2 evolution at high pCO2 levels by AZ, EZ and DIDS and the decreased carbonic anhydrase showed that carbon concentrating mechanisms were down-regulated at high pCO2. In conclusion, our results show that photosynthesis, dark respiration and CCMs will be affected by the increased pCO2/low pH conditions predicted for the future, but that the responses olD. salina to high pCO2/low pH might be modulated by other environmental factors such as light, nutrients and temperature. Therefore, further studies are needed to determine the interactive effects ofpCO2, temperature, light and nutrients on marine microalgae.
基金the National Natural Science Foundation of China (Grant nos. 41506222, 41776205, 41606052, 41606211)Chinese Polar Environment Comprehensive Investigation & Assessment Programs (Grant nos. CHINARE2017-03-04, 2017-04-03)the Fundamental Research Funds for the Second Institute of Oceanography, SOA (Grant nos. JG1611, JG1502)
文摘Over the past decades, the Arctic Ocean has experienced rapid warming under climate change, which has dramatically altered its physical and biogeochemical properties. Reduction in the sea-ice cover is one of the most important driving forces of biogeochemical changes in the Arctic Ocean. Between 1999 and 2016, seven Chinese National Arctic Research Expeditions have taken place in the Bering and Chukchi seas, allowing assessment of the biogeochemical response of the western Arctic Ocean to global warming. Herein, we summarize advances in Chinese and international marine biogeochemistry research in the western Arctic Ocean, reviewing results from the Chinese expeditions and highlighting future trends of biogeochemistry in the Pacific Arctic region. The findings reported in this paper contribute towards a better understanding of water masses, greenhouse gases, nutrients, ocean acidification, and organic carbon export and burial processes in this region.
文摘By the end of the 21st century, mean sea surface temperatures are expected to increase 4?C, while atmospheric CO2 concentrations are predicted to triple causing seawater to become acidic. These compounding effects will undoubtedly have major consequences for the organisms and processes in the oceans. Bacterioplankton play a vital role in the marine carbon cycle and the oceans’ ability to sequester CO2. We utilized pCO2 perturbation experiments to investigate the effects of ocean acidity and elevated temperature on bacterioplankton community structure and metabolism. Terminal-restriction fragment length polymorphism (T-RFLP) of small subunit ribosomal (SSU) genes revealed that bacterioplankton incubated in lower pH conditions exhibited a reduction of species richness, evenness, and overall diversity, relative to those incubated in ambient pH conditions. Non-metric multidimensional scaling (MDS) of T-RFLP data resulted in clustering by pH suggesting that pH influenced the structure of these communities. Shifts in the dominant members of bacterioplankton communities incubated under different pH were observed in both T-RFLP and SSU clone library analyses. Both ambient and low pH communities were dominated by Gammaproteobacteria and Alphaproteobacteria, although abundance of Alphaproteobacteria increased in communities incubated at lower pH. This was expressed by the gamma to alpha ratio dropping from ~9 to 4, respectively. In general, the representative taxa from these two classes were distinctly different between the treatments, with a few taxa found to be persistent in both treatments. Changes in the structure of bacterioplankton communities coincided with significant changes to their overall metabolism. Bacterial production rates decreased, while bacterial respiration increased under lower pH conditions. This study highlights the ability of bacterioplankton communities to respond to ocean acidification both structurally and metabolically, which may have significant implications for their ecological function in the marine carbon cycle and the ocean’s response to global climate change.
基金supported by the National Natural Science Foundation of China[grant number 41975103].
文摘Solar radiation modification(SRM,also termed as geoengineering)has been proposed as a potential option to counteract anthropogenic warming.The underlying idea of SRM is to reduce the amount of sunlight reaching the atmosphere and surface,thus offsetting some amount of global warming.Here,the authors use an Earth system model to investigate the impact of SRM on the global carbon cycle and ocean biogeochemistry.The authors simulate the temporal evolution of global climate and the carbon cycle from the pre-industrial period to the end of this century under three scenarios:the RCP4.5 CO_(2) emission pathway,the RCP8.5 CO_(2) emission pathway,and the RCP8.5 CO_(2) emission pathway with the implementation of SRM to maintain the global mean surface temperature at the level of RCP4.5.The simulations show that SRM,by altering global climate,also affects the global carbon cycle.Compared to the RCP8.5 simulation without SRM,by the year 2100,SRM reduces atmospheric CO_(2) by 65 ppm mainly as a result of increased CO_(2) uptake by the terrestrial biosphere.However,SRM-induced change in atmospheric CO_(2) and climate has a small effect in mitigating ocean acidification.By the year 2100,relative to RCP8.5,SRM causes a decrease in surface ocean hydrogen ion concentration([H^(+)])by 6% and attenuates the seasonal amplitude of[H^(+)]by about 10%.The simulations also show that SRM has a small effect on globally integrated ocean net primary productivity relative to the high-CO_(2) simulation without SRM.This study contributes to a comprehensive assessment of the effects of SRM on both the physical climate and the global carbon cycle.
基金Supported by the National Natural Science Foundation of China(No.31872587)the Shanghai Pujiang Program(No.18PJ1404000)the Shanghai Municipal Natural Science Foundation(No.17ZR1412900)。
文摘Ocean acidification(OA)affects marine biodiversity and alters the structure and function of marine populations,communities,and ecosystems.Recently,effects of OA on the behavioral responses of marine animals have been given with much attention.While many of previous studies focuses on marine fish.Evidence suggests that marine invertebrate behaviors were also be affected.In this review,we discussed the effects of CO2-driven OA on the most common behaviors studied in marine invertebrates,including settlement and habitat selection,feeding,anti-predatory,and swimming behaviors,and explored the related mechanisms behind behaviors.This review summarizes how OA affects marine invertebrate behavior,and provides new insights and highlights novel areas for future research.
基金supported by the Key Research and Development Program of Shandong Province(No.2020 ZLYS04)the National Key Research and Development Program of China(No.2017YFA0604300)+2 种基金the Qingdao Pilot National Laboratory for Marine Science and Technology(No.2018SDKJ0105-1)the Fundamental Research Funds for the Central Universities(No.202072001)the Young Scholars Program of Shandong University(No.2018WLJH43).
文摘The problem of ocean acidification caused by the increase of atmospheric carbon dioxide concentration is becoming increasingly prominent.Field observation in the northwest Pacific Ocean was carried out along the 150°E transect in November 2019.The distribution characteristics and influencing factors of the surface seawater carbonate chemistry,including dissolved inorganic carbon(DIC),total alkalinity(TA),pH,partial pressure of carbon dioxide(pCO_(2))and aragonite saturation state(Ω_(arag))were investigated.DIC and TA ranged from 1915 to 2014μmol kg^(−1)and 2243 to 2291μmol kg^(−1),respectively;DIC in general decreased with decreasing latitude,but TA had no clear latitudinal gradient.pCO_(2)values increased with the decrease of latitude and were all below the atmospheric pCO_(2)level,ranging from 332 to 387μatm.pH on the total hydrogen ion concentration scale(pH_(T))decreased with the decrease of latitude in the range of 8.044–8.110,whileΩ_(arag) increased with the decrease of latitude in the range of 2.61–3.88,suggesting that the spatial distributions of pH_(T) andΩ_(arag) were out of phase.Compared with the present,the predicted values of pH_(T) and Ω_(arag) by the end of this century would decrease remarkedly;larger declines were found in the higher pH_(T) and Ω_(arag) regions,resulting in the differences along the meridional gradient becoming smaller for bothpH_(T) and Ω_(arag).
基金Supported by the earmarked fund for Modern Agro-industry Technology Research System(No.CARS-48)
文摘Although the impact of ocean acidification on marine bivalves has been previously investigated under mainly controlled laboratory conditions,it is still unclear whether the impact of acidification on sediment-burrowing species differs between those within or without sediment.In order to fill this gap in our knowledge,we compared shell properties of the infaunal Manila clam(Ruditapes philippinarum)exposed to three pH concentrations(7.4,7.7,and 8.0),within and without sediments.In the first experiment(140 d),clams were exposed to seawater in an acidification system without sediment.A decrease in shell weight corresponding to the increase in dissolution rate was observed in the group ofpH 7.4,at which shell color disappeared or whitened.SEM observations confirmed the changes of the external shell surface.In the second experiment(170 d),sediment was placed at the bottom of each exposure chamber.The effects were found obvious in shell dissolution rate and shell color in the shell specimens exposed to overlying seawater but not found in the shell specimens exposed to sediment.Although the experimental period was longer in the second experiment,shell specimens in the first experiment were more seriously damaged than those in the second experiment under acidic seawater conditions.Our results,in relation to the defense function of the shell,show that marine bivalves in burrowing behavior are more adaptable to seawater acidification than those who do not burrow into sediment.
