Wetlands worldwide have suffered from serious degradation and transformation,leading to waterbirds increasingly dependent on agricultural fields for feeding.Although gut microbiota is an essential component of host he...Wetlands worldwide have suffered from serious degradation and transformation,leading to waterbirds increasingly dependent on agricultural fields for feeding.Although gut microbiota is an essential component of host health,the impacts of agricultural feeding on gut microbial community and pathogen transmission remain poorly understood.To fill this knowledge gap,we used 16S rRNA sequencing to characterize the fecal bacterial community of the Siberian Crane(Grus leucogeranus),a Critically Endangered species,that recently has shifted its foraging from largely Vallisneria tubers in Poyang Lake natural wetlands to crops(i.e.,rice seeds and lotus rhizomes) in agricultural fields.We compared the bacterial communities between tuber foraging cranes and crop foraging cranes.Our results indicate that diet shift greatly modified the gut microbiota diversity,composition and function.Crop foraging cranes had higher microbiota diversity than tuber foraging cranes.The alteration in microbiota composition and function were correlated with change in food nutrition.Tuber(i.e.,high in fiber)foraging cranes were enriched in Clostridiaceae with fiber digestion ability,and crop(i.e.,high in carbohydrate)foraging cranes were enriched in bacterial taxa and functions related to carbohydrate metabolism.The flexibility of gut microbiota might enhance Siberian Cranes’ ability to adapt to novel diet and environment.However,many enriched families in crop foraging cranes were pathogenic bacteria,which might increase the susceptibility of cranes to pathogenic infection.Special caution should be taken to agricultural feeding waterbirds in Asia,where the widespread poultry-keeping in over-harvested rice fields might increase the transmission probability of pathogenetic bacteria among wild birds,domestic poultry and humans.展开更多
As one of the most common and dominant species in the Southern Ocean, Antarctic krill（Euphausia superba）play a significant role in food web structure and the process of energy flow. The diet of Antarctic krill in th...As one of the most common and dominant species in the Southern Ocean, Antarctic krill（Euphausia superba）play a significant role in food web structure and the process of energy flow. The diet of Antarctic krill in the Prydz Bay during austral summer of 2012/2013 was investigated and the ontogenetic shift in krill diet was evaluated using the stable isotope method. The nitrogen stable isotope values（δ^（15） N） of adults（（2.78±0.58）‰） were much higher than those of juveniles（（1.69±0.70）‰）, whereas the carbon stable isotope values（δ^（13） C） of adults（–（28.26±1.08）‰） were slightly lower than those of juveniles（–（27.48±1.35）‰）. Particulate organic matter（POM）from 0, 25, and 50 m depth combined（0/25/50 m） represented phytoplankton food items. The results showed that phytoplankton food items in surface water and mesozooplankton were two essential food items for Antarctic krill in the Prydz Bay during summer. POM（0/25/50 m） contributes 56%–69% and 26%–34% to the diet of juvenile and adult krill, respectively, whereas mesozooplankton composes 13%–34% and 58%–71% of the diet of juvenile and adult krill, respectively. Thus, an ontogenetic diet shift from POM（0/25/50 m）, which consists mainly of phytoplankton, to a higher trophic level diet containing mesozooplankton, was detected. The capacity for adults to consume more zooplankton food items may minimize their food competition with juveniles, which rely mostly on phytoplankton food items. This suggests ＂diet shift with ontogeny＂ which may somehow help krill keep their dietary energy budget balanced and well adapted to the Antarctic marine ecosystem as a dominant species.展开更多
Grey-sided voles(Myodes rufocanus)and bank voles(Myodes glareolus)co-exist in boreal forests in northern Scandinavia.Previous studies suggest that the 2 species interact interspecifically,the grey-sided vole be&...Grey-sided voles(Myodes rufocanus)and bank voles(Myodes glareolus)co-exist in boreal forests in northern Scandinavia.Previous studies suggest that the 2 species interact interspecifically,the grey-sided vole being the dominant species.We tested the hypothesis that bank voles shift their diet due to competition with the dominant grey-sided vole by studying stable isotope ratios in both species.Muscle samples were taken from voles in patches of old forest occupied by only bank voles and patches of old forest occupied by both grey-sided voles and bank voles.We found that:(i)stable isotope ratios of bank voles differed in areas with and without grey-sided voles;and that(ii)the stable isotope ratios of bank voles were more similar to those of grey-sided voles in areas where grey-sided voles were absent.Our data suggests that grey-sided voles forced bank voles to change their diet due to interspecific competition.展开更多
Analysis of historical and recent data is essential to understand how eutrophication and/or climate change might trigger shifts in the feeding mode of fish and trophic dynamics of shallow lakes. To assess long-term ch...Analysis of historical and recent data is essential to understand how eutrophication and/or climate change might trigger shifts in the feeding mode of fish and trophic dynamics of shallow lakes. To assess long-term changes in the diet and growth of juvenile pikeperch (Sander lucioperca), the prey selection and growth of pikeperch fry from Lake V?rtsj?rv was investigated in 2007 - 2010 and compared with data from 1920 to 1970. Over the observed period, larger cladocerans have become less frequent in the diet as eutrophication has altered the zooplankton community. Furthermore, climate change has triggered a mismatch between the predator and its prey: the smelt population has collapsed but other fish fries are too large for YOY (young-of-the-year) pikeperch. However, the mean length of fish has decreased mainly due to the postponed diet shift.展开更多
We evaluated the feeding ecology of largehead hairtail (Trichiurus lepturus) and hairtail (T. margarites). We collected specimens from fishing ports in the Beibu Gulf (Gulf of Tonkin) from October 2008 to September 20...We evaluated the feeding ecology of largehead hairtail (Trichiurus lepturus) and hairtail (T. margarites). We collected specimens from fishing ports in the Beibu Gulf (Gulf of Tonkin) from October 2008 to September 2009 and analyzed their gut contents. We collected 857 T. lepturus and 666 T. margarites samples. The number of stomachs examined in this study was sufficient to describe the monthly and ontogenetic diet shifts for the two species, as indicated by the trophic diversity curves. T. lepturus was a general omnivore, feeding primarily on Bregmaceros rarisquamosu, Decapterus maruadsi, and Acetes chinensis. Conversely, T. margarites preyed primarily on D. maruadsi, B. rarisquamosus, B. nectabanus, and A. chinensis. Both species exhibited distinct ontogenetic diet shifts. Although the two hairtail specie fed on similar sources in the same habitat, the diet overlap was relatively low. Our results suggest that hairtail play an important role in controlling small pelagic and benthic fish populations in the gulf. This trophic correlation shall be used for developing a marine ecosystem model for the Beibu Gulf.展开更多
Introduction:The purpose of this study was to assess enrichments in stable carbon and nitrogen isotopes(δ^(13)C andδ^(15)N)in brown-marbled groupers(Epinephelus fuscoguttatus),a marine fish that has been widely used...Introduction:The purpose of this study was to assess enrichments in stable carbon and nitrogen isotopes(δ^(13)C andδ^(15)N)in brown-marbled groupers(Epinephelus fuscoguttatus),a marine fish that has been widely used in aquaculture.Stable isotope analysis has been used to evaluate dietary sources and the trophic position of fish.There is the need to better understand the pattern of isotope enrichment between consumers and diets under laboratory conditions.Methods:We studied the changes in stable carbon and nitrogen isotopes of juvenile brown-marbled groupers during a feeding experiment in 2009.Fish were grown in aquaria and fed a sole source of protein for 56 days and analyzed forδ^(13)C andδ^(15)N ratios in whole fish,muscle,and liver tissues.Results:At the end of the 56-day feeding experiment,fish grew to an average of 55.6 g from an average of 22.5 g.Compared to the dietary isotope compositions,whole fish and muscle tissues of the juvenile groupers were enriched inδ^(13)C by 1.6 and 0.5%,while the liver was depleted by 1.3%.Theδ^(15)N enrichments were 1.6%for whole fish,1.3%for muscle,and 1.0%for liver.Except for liver,δ^(15)N isotope values increased significantly with time.Conclusions:The small change inδ^(13)C between the diet and fish suggests that little isotope alteration is occurring during the assimilation of dietary carbon.This provides a basis for estimates of the importance of different sources of dietary components when contrasted with the isotope values from a formulated diet with known isotope values of the different components.The smaller than expectedδ^(15)N enrichment in all tissue suggests that isotope values from a wild fish sample may not always reach isotope equilibrium with the current diet,and an inference about recent dietary sources and an estimate of the consumer’s trophic position should be evaluated with caution.展开更多
基金the National Natural Science Foundation of China(Grant No.32160132,31772480).
文摘Wetlands worldwide have suffered from serious degradation and transformation,leading to waterbirds increasingly dependent on agricultural fields for feeding.Although gut microbiota is an essential component of host health,the impacts of agricultural feeding on gut microbial community and pathogen transmission remain poorly understood.To fill this knowledge gap,we used 16S rRNA sequencing to characterize the fecal bacterial community of the Siberian Crane(Grus leucogeranus),a Critically Endangered species,that recently has shifted its foraging from largely Vallisneria tubers in Poyang Lake natural wetlands to crops(i.e.,rice seeds and lotus rhizomes) in agricultural fields.We compared the bacterial communities between tuber foraging cranes and crop foraging cranes.Our results indicate that diet shift greatly modified the gut microbiota diversity,composition and function.Crop foraging cranes had higher microbiota diversity than tuber foraging cranes.The alteration in microbiota composition and function were correlated with change in food nutrition.Tuber(i.e.,high in fiber)foraging cranes were enriched in Clostridiaceae with fiber digestion ability,and crop(i.e.,high in carbohydrate)foraging cranes were enriched in bacterial taxa and functions related to carbohydrate metabolism.The flexibility of gut microbiota might enhance Siberian Cranes’ ability to adapt to novel diet and environment.However,many enriched families in crop foraging cranes were pathogenic bacteria,which might increase the susceptibility of cranes to pathogenic infection.Special caution should be taken to agricultural feeding waterbirds in Asia,where the widespread poultry-keeping in over-harvested rice fields might increase the transmission probability of pathogenetic bacteria among wild birds,domestic poultry and humans.
基金Chinese Polar Environment Comprehensive Investigation&Assessment Programmes under contract No.CHINARE2016-01-05the Scientific and Technological Innovation Project financially supported by Qingdao National Laboratory for Marine Science and Technology under contract No.2015ASKJ01the National Natural Science Foundation of China under contract No.41206180
文摘As one of the most common and dominant species in the Southern Ocean, Antarctic krill（Euphausia superba）play a significant role in food web structure and the process of energy flow. The diet of Antarctic krill in the Prydz Bay during austral summer of 2012/2013 was investigated and the ontogenetic shift in krill diet was evaluated using the stable isotope method. The nitrogen stable isotope values（δ^（15） N） of adults（（2.78±0.58）‰） were much higher than those of juveniles（（1.69±0.70）‰）, whereas the carbon stable isotope values（δ^（13） C） of adults（–（28.26±1.08）‰） were slightly lower than those of juveniles（–（27.48±1.35）‰）. Particulate organic matter（POM）from 0, 25, and 50 m depth combined（0/25/50 m） represented phytoplankton food items. The results showed that phytoplankton food items in surface water and mesozooplankton were two essential food items for Antarctic krill in the Prydz Bay during summer. POM（0/25/50 m） contributes 56%–69% and 26%–34% to the diet of juvenile and adult krill, respectively, whereas mesozooplankton composes 13%–34% and 58%–71% of the diet of juvenile and adult krill, respectively. Thus, an ontogenetic diet shift from POM（0/25/50 m）, which consists mainly of phytoplankton, to a higher trophic level diet containing mesozooplankton, was detected. The capacity for adults to consume more zooplankton food items may minimize their food competition with juveniles, which rely mostly on phytoplankton food items. This suggests ＂diet shift with ontogeny＂ which may somehow help krill keep their dietary energy budget balanced and well adapted to the Antarctic marine ecosystem as a dominant species.
基金the anonymous reviewers for their constructive comments.Financial support was received from stiftelsen Oscar och Lili Lamms minne,from Helge Ax:son Johnsons stiftelse and from the Swedish Research Council FORMAS(Dnr 2017-00867).
文摘Grey-sided voles(Myodes rufocanus)and bank voles(Myodes glareolus)co-exist in boreal forests in northern Scandinavia.Previous studies suggest that the 2 species interact interspecifically,the grey-sided vole being the dominant species.We tested the hypothesis that bank voles shift their diet due to competition with the dominant grey-sided vole by studying stable isotope ratios in both species.Muscle samples were taken from voles in patches of old forest occupied by only bank voles and patches of old forest occupied by both grey-sided voles and bank voles.We found that:(i)stable isotope ratios of bank voles differed in areas with and without grey-sided voles;and that(ii)the stable isotope ratios of bank voles were more similar to those of grey-sided voles in areas where grey-sided voles were absent.Our data suggests that grey-sided voles forced bank voles to change their diet due to interspecific competition.
文摘Analysis of historical and recent data is essential to understand how eutrophication and/or climate change might trigger shifts in the feeding mode of fish and trophic dynamics of shallow lakes. To assess long-term changes in the diet and growth of juvenile pikeperch (Sander lucioperca), the prey selection and growth of pikeperch fry from Lake V?rtsj?rv was investigated in 2007 - 2010 and compared with data from 1920 to 1970. Over the observed period, larger cladocerans have become less frequent in the diet as eutrophication has altered the zooplankton community. Furthermore, climate change has triggered a mismatch between the predator and its prey: the smelt population has collapsed but other fish fries are too large for YOY (young-of-the-year) pikeperch. However, the mean length of fish has decreased mainly due to the postponed diet shift.
基金Supported by the National Natural Science Foundation of China (No.30771653)the Bureau of Fisheries,Ministry of Agriculture,Department of Education of Guangdong Province (No.LYM09089)Guangdong Ocean University (No.2009-11)
文摘We evaluated the feeding ecology of largehead hairtail (Trichiurus lepturus) and hairtail (T. margarites). We collected specimens from fishing ports in the Beibu Gulf (Gulf of Tonkin) from October 2008 to September 2009 and analyzed their gut contents. We collected 857 T. lepturus and 666 T. margarites samples. The number of stomachs examined in this study was sufficient to describe the monthly and ontogenetic diet shifts for the two species, as indicated by the trophic diversity curves. T. lepturus was a general omnivore, feeding primarily on Bregmaceros rarisquamosu, Decapterus maruadsi, and Acetes chinensis. Conversely, T. margarites preyed primarily on D. maruadsi, B. rarisquamosus, B. nectabanus, and A. chinensis. Both species exhibited distinct ontogenetic diet shifts. Although the two hairtail specie fed on similar sources in the same habitat, the diet overlap was relatively low. Our results suggest that hairtail play an important role in controlling small pelagic and benthic fish populations in the gulf. This trophic correlation shall be used for developing a marine ecosystem model for the Beibu Gulf.
基金This study was supported by grants A200608C02,A200908D03,2006B20201059,and 2009B020308005 from several funding agencies of the Guangdong Province government,China.Dr.Thomas Dreschel provided language improvements on the final draft of this manuscript.
文摘Introduction:The purpose of this study was to assess enrichments in stable carbon and nitrogen isotopes(δ^(13)C andδ^(15)N)in brown-marbled groupers(Epinephelus fuscoguttatus),a marine fish that has been widely used in aquaculture.Stable isotope analysis has been used to evaluate dietary sources and the trophic position of fish.There is the need to better understand the pattern of isotope enrichment between consumers and diets under laboratory conditions.Methods:We studied the changes in stable carbon and nitrogen isotopes of juvenile brown-marbled groupers during a feeding experiment in 2009.Fish were grown in aquaria and fed a sole source of protein for 56 days and analyzed forδ^(13)C andδ^(15)N ratios in whole fish,muscle,and liver tissues.Results:At the end of the 56-day feeding experiment,fish grew to an average of 55.6 g from an average of 22.5 g.Compared to the dietary isotope compositions,whole fish and muscle tissues of the juvenile groupers were enriched inδ^(13)C by 1.6 and 0.5%,while the liver was depleted by 1.3%.Theδ^(15)N enrichments were 1.6%for whole fish,1.3%for muscle,and 1.0%for liver.Except for liver,δ^(15)N isotope values increased significantly with time.Conclusions:The small change inδ^(13)C between the diet and fish suggests that little isotope alteration is occurring during the assimilation of dietary carbon.This provides a basis for estimates of the importance of different sources of dietary components when contrasted with the isotope values from a formulated diet with known isotope values of the different components.The smaller than expectedδ^(15)N enrichment in all tissue suggests that isotope values from a wild fish sample may not always reach isotope equilibrium with the current diet,and an inference about recent dietary sources and an estimate of the consumer’s trophic position should be evaluated with caution.
