Seasonal fishing closures are often used in fisheries management to conserve overfished stocks.As one of the unintended consequences,fishermen often contend for maximizing catches immediately after reopening fisheries...Seasonal fishing closures are often used in fisheries management to conserve overfished stocks.As one of the unintended consequences,fishermen often contend for maximizing catches immediately after reopening fisheries.The resultant large catch landings in a short time period(i.e.,pulse fishing)may undermine the benefit of closure.We implemented an end-to-end model OSMOSE-JZB(Object-oriented Simulator of Marine ec OSystem Exploitation OSMOSE)modelling ecosystem in the Jiaozhou Bay located in China to evaluate the impact of pulse fishing on the effectiveness of seasonal closure at levels of fish community,population,and individual.Our study demonstrated that the three-month closure was successful in conserving fish stocks.There were small variations on ecological indicators(i.e.,total biomass of the community,mean trophic level of the community,mean trophic level of the catch,and Shannon-Wiener biodiversity index)when pulse fishing occurred.Pulse fishing seemed not to result in a great shift in community structure.Compared to other species,the biomass of two large predatory fishes were more susceptible to pulse fishing.Pulse fishing could change the pressure of predators to fish stocks via food webs,especially for young individuals.Our simulations indicate that we can improve the effectiveness of seasonal closure by managing pulse fishing.Although the results derived in this study may be specific to the target ecosystem,the general approach is applicable to other ecosystems when evaluating fishing impacts.展开更多
Background:The present article questions the relative importance of local-and large-scale processes on the long-term dynamics of fire in the subalpine belt in the western Alps.The study is based on soil charcoal datin...Background:The present article questions the relative importance of local-and large-scale processes on the long-term dynamics of fire in the subalpine belt in the western Alps.The study is based on soil charcoal dating and identification,several study sites in contrasting environmental conditions,and sampling of soil charcoal along the elevation gradient of each site.Based on local differences in biomass combustion,we hypothesize that local-scale or landscape-scale processes have driven the fire history,while combustion homogeneity supports the hypothesis of the importance of large-scale or macro-ecological processes,especially climate.Results:Biomass burning during the Holocene resulted from the nesting effects of climate,land use,and altitude,but was little influenced by slope exposure(north versus south),soil(dryness,pH,depth),and vegetation.The mid-Holocene(6500–2700 cal BP)was an important period for climate-driven biomass burning in the subalpine ecosystems of the western Alps,while fires over the last 2500 years appear much more episodic,prompting us to speculate that human activity has played a vital role in their occurrence.Conclusion:Our working hypothesis that the strength of local drivers should offset the effects of regional climate is not validated.The homogeneity of the fire regime between sites thus underscores that climate was the main driver during the Holocene of the western Alps.Long-term subalpine fires are controlled by climate at the millennial scale.Local conditions matter for little in determining variability at the century scale.The mid-Holocene was a chief period for climatic biomass burning in the subalpine zone,while fires during the late Holocene appear much more episodic,suggesting that social drivers has exercised key function on their control.展开更多
The effects of Hg exposure on blood parameters and gill physiology of tilapia(Oreochromis niloticus)were analyzed.Fish maintained in freshwater were exposed for 7 days(d)to sublethal mercury concentrations(0.1 and 1 m...The effects of Hg exposure on blood parameters and gill physiology of tilapia(Oreochromis niloticus)were analyzed.Fish maintained in freshwater were exposed for 7 days(d)to sublethal mercury concentrations(0.1 and 1 mg/L).Blood serum osmolality(SO),sodium(Nat),potassium(K^+)and chloride(Cl^-)ionic concentrations,and hematological parameters were assessed after 1 up to 7 d of exposure.Serum osmolality and ionic concentrations of exposed fish appeared differently affected throughout the experimental period compared to the controls.Osmolality was reduced at the 2 tested concentrations but Nat and Cl^-contents were only altered at 1 mg/L of Hg after 1 d of exposure and values rapidly returned to the control values thereafter.K^+content was also modified and significantly increased at both concentrations after 1 d of exposure but returned to the control values after 3 d of exposure.Red blood cell(RBC),white blood cell(WBC)and hemoglobin(Hb)levels were significantly increased throughout the experiment but returned to control values after 7 d of exposure only for the 0.1 mg/L concentration.The hematocrit(Ht)levels remained unaffected due to Hg exposure.Therefore,tilapias exposed to sublethal concentrations of Hg present a marked osmotic imbalance with ionic and hematological disorders that are rapidly compensated.展开更多
Due to the tremendous diversity of microbial organisms in topsoil,the estimation of saturated richness in a belowground ecosystem is still challenging.Here,we intensively surveyed the 16S rRNA gene in four 1 m2 sampli...Due to the tremendous diversity of microbial organisms in topsoil,the estimation of saturated richness in a belowground ecosystem is still challenging.Here,we intensively surveyed the 16S rRNA gene in four 1 m2 sampling quadrats in a typical grassland,with 141 biological or technical replicates generating over 11 million sequences per quadrat.Through these massive data sets and using both non-asymptotic extrapolation and non-parametric asymptotic approaches,results revealed that roughly 15919±193,27193±1076 and 56985±2347 prokaryotic species inhabited in 1 m2 topsoil,classifying by DADA2,UPARSE(97%cutoff)and Deblur,respectively,and suggested a huge difference among these clustering tools.Nearly 500000 sequences were required to catch 50%species in 1 m2,while any estimator based on 500000 sequences would still lose about a third of total richness.Insufficient sequencing depth will greatly underestimate both observed and estimated richness.At least~911000,~3461000,and~1878000 sequences were needed for DADA2,UPARSE,and Deblur,respectively,to catch 80%species in 1 m2 topsoil,and the numbers of sequences would be nearly twice to three times on this basis to cover 90%richness.In contrast,α-diversity indexes characterized by higher order of Hill numbers,including Shannon entropy and inverse Simpson index,reached saturation with fewer than 100000 sequences,suggesting sequencing depth could be varied greatly when focusing on exploring differentα-diversity characteristics of a microbial community.Our findings were fundamental for microbial studies that provided benchmarks for the extending surveys in large scales of terrestrial ecosystems.展开更多
Chemical pollution is a widespread stressor for wild organisms,but its effects on molecular damage and aging are still poorly understood.Telomere attrition has been used as an integrative biomarker of aging and stress...Chemical pollution is a widespread stressor for wild organisms,but its effects on molecular damage and aging are still poorly understood.Telomere attrition has been used as an integrative biomarker of aging and stress exposure in endotherms.However,the effects of organic pollution on telomere length remain unclear,especially in ectotherms such as fish.We compared telomere length in fish gills across different populations of a short-lived invasive species,the mosquitofish(Gambusia holbrooki),exposed to organic pollution,or salinity.We expected lower telomere length in fish from more polluted and/or saline habitats due to increased oxidative stress.Contrary to our predictions,telomere length was unchanged in agricultural and port habitats and was higher in populations exposed to increased salinity and industrial pollution.A significant change in oxidative stress status in the liver was observed in response to increased salinity but no clear response was evident regarding pollution.Although the underlying mechanisms remain to be explored,this study suggests protective processes limiting telomere attrition or selective processes favoring individuals with longer telomeres.We also encourage further empirical approaches to study telomere attrition in aquatic ectotherms,particularly in fish exposed to multiple environmental stressors.展开更多
基金The Fundamental Research Funds for the Central Universities under contract Nos 201512002 and 201612002
文摘Seasonal fishing closures are often used in fisheries management to conserve overfished stocks.As one of the unintended consequences,fishermen often contend for maximizing catches immediately after reopening fisheries.The resultant large catch landings in a short time period(i.e.,pulse fishing)may undermine the benefit of closure.We implemented an end-to-end model OSMOSE-JZB(Object-oriented Simulator of Marine ec OSystem Exploitation OSMOSE)modelling ecosystem in the Jiaozhou Bay located in China to evaluate the impact of pulse fishing on the effectiveness of seasonal closure at levels of fish community,population,and individual.Our study demonstrated that the three-month closure was successful in conserving fish stocks.There were small variations on ecological indicators(i.e.,total biomass of the community,mean trophic level of the community,mean trophic level of the catch,and Shannon-Wiener biodiversity index)when pulse fishing occurred.Pulse fishing seemed not to result in a great shift in community structure.Compared to other species,the biomass of two large predatory fishes were more susceptible to pulse fishing.Pulse fishing could change the pressure of predators to fish stocks via food webs,especially for young individuals.Our simulations indicate that we can improve the effectiveness of seasonal closure by managing pulse fishing.Although the results derived in this study may be specific to the target ecosystem,the general approach is applicable to other ecosystems when evaluating fishing impacts.
基金Financial support was provided to C.C.through a French incentive action fund from the Institut National des Sciences de l’Univers(INSU ACI ECCO)by an ARTEMIS grant for datings(PALEOFIRE program,INSU-CNRS,France).
文摘Background:The present article questions the relative importance of local-and large-scale processes on the long-term dynamics of fire in the subalpine belt in the western Alps.The study is based on soil charcoal dating and identification,several study sites in contrasting environmental conditions,and sampling of soil charcoal along the elevation gradient of each site.Based on local differences in biomass combustion,we hypothesize that local-scale or landscape-scale processes have driven the fire history,while combustion homogeneity supports the hypothesis of the importance of large-scale or macro-ecological processes,especially climate.Results:Biomass burning during the Holocene resulted from the nesting effects of climate,land use,and altitude,but was little influenced by slope exposure(north versus south),soil(dryness,pH,depth),and vegetation.The mid-Holocene(6500–2700 cal BP)was an important period for climate-driven biomass burning in the subalpine ecosystems of the western Alps,while fires over the last 2500 years appear much more episodic,prompting us to speculate that human activity has played a vital role in their occurrence.Conclusion:Our working hypothesis that the strength of local drivers should offset the effects of regional climate is not validated.The homogeneity of the fire regime between sites thus underscores that climate was the main driver during the Holocene of the western Alps.Long-term subalpine fires are controlled by climate at the millennial scale.Local conditions matter for little in determining variability at the century scale.The mid-Holocene was a chief period for climatic biomass burning in the subalpine zone,while fires during the late Holocene appear much more episodic,suggesting that social drivers has exercised key function on their control.
基金The authors are grateful to the Ministry of Research,Technology and Higher Education of Republic of Indonesia,Directorate General of Resources for Science Technology and Higher Education for supporting this work under the Sandwich-Like Program at the University of Montpellier(Grant no.1406.58/D3/PG/2018).
文摘The effects of Hg exposure on blood parameters and gill physiology of tilapia(Oreochromis niloticus)were analyzed.Fish maintained in freshwater were exposed for 7 days(d)to sublethal mercury concentrations(0.1 and 1 mg/L).Blood serum osmolality(SO),sodium(Nat),potassium(K^+)and chloride(Cl^-)ionic concentrations,and hematological parameters were assessed after 1 up to 7 d of exposure.Serum osmolality and ionic concentrations of exposed fish appeared differently affected throughout the experimental period compared to the controls.Osmolality was reduced at the 2 tested concentrations but Nat and Cl^-contents were only altered at 1 mg/L of Hg after 1 d of exposure and values rapidly returned to the control values thereafter.K^+content was also modified and significantly increased at both concentrations after 1 d of exposure but returned to the control values after 3 d of exposure.Red blood cell(RBC),white blood cell(WBC)and hemoglobin(Hb)levels were significantly increased throughout the experiment but returned to control values after 7 d of exposure only for the 0.1 mg/L concentration.The hematocrit(Ht)levels remained unaffected due to Hg exposure.Therefore,tilapias exposed to sublethal concentrations of Hg present a marked osmotic imbalance with ionic and hematological disorders that are rapidly compensated.
基金the National Natural Science Foundation of China(NSFC Grant No.U1906223)the National Key Research and Development Program(Grant No.2019YFC1905001)。
文摘Due to the tremendous diversity of microbial organisms in topsoil,the estimation of saturated richness in a belowground ecosystem is still challenging.Here,we intensively surveyed the 16S rRNA gene in four 1 m2 sampling quadrats in a typical grassland,with 141 biological or technical replicates generating over 11 million sequences per quadrat.Through these massive data sets and using both non-asymptotic extrapolation and non-parametric asymptotic approaches,results revealed that roughly 15919±193,27193±1076 and 56985±2347 prokaryotic species inhabited in 1 m2 topsoil,classifying by DADA2,UPARSE(97%cutoff)and Deblur,respectively,and suggested a huge difference among these clustering tools.Nearly 500000 sequences were required to catch 50%species in 1 m2,while any estimator based on 500000 sequences would still lose about a third of total richness.Insufficient sequencing depth will greatly underestimate both observed and estimated richness.At least~911000,~3461000,and~1878000 sequences were needed for DADA2,UPARSE,and Deblur,respectively,to catch 80%species in 1 m2 topsoil,and the numbers of sequences would be nearly twice to three times on this basis to cover 90%richness.In contrast,α-diversity indexes characterized by higher order of Hill numbers,including Shannon entropy and inverse Simpson index,reached saturation with fewer than 100000 sequences,suggesting sequencing depth could be varied greatly when focusing on exploring differentα-diversity characteristics of a microbial community.Our findings were fundamental for microbial studies that provided benchmarks for the extending surveys in large scales of terrestrial ecosystems.
基金funded by the Occitanie Regional Council's program“Key challenge Biodivoc”(GambOc project)E.F.is supported by the ANR PRC POLADAPT ANR-23-CE34-0015-01N.M.was financed by the GambOc project and the graduated school EUR TULIP.LJ is supported by the IUF.
文摘Chemical pollution is a widespread stressor for wild organisms,but its effects on molecular damage and aging are still poorly understood.Telomere attrition has been used as an integrative biomarker of aging and stress exposure in endotherms.However,the effects of organic pollution on telomere length remain unclear,especially in ectotherms such as fish.We compared telomere length in fish gills across different populations of a short-lived invasive species,the mosquitofish(Gambusia holbrooki),exposed to organic pollution,or salinity.We expected lower telomere length in fish from more polluted and/or saline habitats due to increased oxidative stress.Contrary to our predictions,telomere length was unchanged in agricultural and port habitats and was higher in populations exposed to increased salinity and industrial pollution.A significant change in oxidative stress status in the liver was observed in response to increased salinity but no clear response was evident regarding pollution.Although the underlying mechanisms remain to be explored,this study suggests protective processes limiting telomere attrition or selective processes favoring individuals with longer telomeres.We also encourage further empirical approaches to study telomere attrition in aquatic ectotherms,particularly in fish exposed to multiple environmental stressors.
