Fish scaleδ^(15)N(δ^(15)N_(sca))records trophic information of the whole life history for marine fishes.Data from gut content and values calculated from white muscle tissue(WMT)are insufficient for assessing trophic...Fish scaleδ^(15)N(δ^(15)N_(sca))records trophic information of the whole life history for marine fishes.Data from gut content and values calculated from white muscle tissue(WMT)are insufficient for assessing trophic level(TL)of marine fishes as they only provide the information of several months or even several days.Stable isotope analysis(SIA)of nitrogen was carried out in fish scales and WMT of 16 species from a total of 28 individuals captured from the Yellow Sea and northern East China Sea in October and November of 2019,aiming at discovering the correlation betweenδ^(15)N_(sca) and fish WMTδ^(15)N(δ^(15)NWMT),so as to useδ^(15)N_(sca) for the characterization of TLs of marine fish.Scales were analyzed without prior carbonate dissolution as a pre-processing step.TL calculated fromδ^(15)N_(sca) was compared to traditional TL formula calculated withδ^(15)N_(WMT) to estimate the accuracy.We found that there was a highly significant and positive correlation(r=0.830,P<0.001)betweenδ^(15)N_(sca) andδ^(15)N_(WMT).TL calculation results using fish scale(TL_(sca))and WMT(TL_(WMT))showed congruence(r=0.773,P<0.001),and the regression coefficient betweenδ^(15)N_(sca) andδ^(15)NWMT was used for calculating TLsca.The conversion was conducted for the purpose of comparison with previousδ^(15)N_(WMT)-based calculation results of TL.TLsca calculation results were 81.25%within the TL range of±10%calculated withδ^(15)NWMT.The findings in the present study showed thatδ^(15)N_(sca) is a viable technique for the characterization of the TL of marine fish and can help to predict food web and support the study of marine ecosystem.展开更多
Understanding the catch composition of multispecies fisheries is fundamental to effective spatial fishery management.In the Equatorial Western and Central Pacific Ocean(EWCPO),the main catches of the tuna purse-seine ...Understanding the catch composition of multispecies fisheries is fundamental to effective spatial fishery management.In the Equatorial Western and Central Pacific Ocean(EWCPO),the main catches of the tuna purse-seine fishery include skipjack tuna(Katsuwonus pelamis),yellowfin tuna(Thunnus albacares),and bigeye tuna(Thunnus obesus).Studying the spatiotemporal distribution of the catch composition in the context of climate change contributes to the sustainable development of this fishery.Our study analyzed purse seine fishery data and environmental data from 1997 to 2019,using a random forest model to explore the changing mechanisms of catch composition under different El Niño-Southern Oscillation(ENSO)episodes with catch mean trophic level(CMTL)as the response variable.Emerging hot spot analysis was used to identify significant spatiotemporal hot(cold)spot areas.The results revealed two hot spot areas,namely the western hotspot area(WHA)and the eastern hotspot area(EHA),and two cold spot areas,namely the northern cold spot area(NCA)and the southern cold spot area(SCA).EHA spans the entire central Pacific east of 170°E among different ENSO episodes,expanding and contracting in tandem with the 28℃isotherm.WHA is mainly influenced by surface organic matter and the Western Boundary Currents and remains among different ENSO episodes.NCA is formed by the westerly anomalies and positive wind stress curl anomalies and exists only under La Niña episodes.SCA persists within the unproductive South Equatorial Current(SEC)and remains stable among different ENSO episodes.Our study contributes to revealing the spatiotemporal dynamics in tuna catch composition and their relationships with environmental factors and interspecies competition,providing valuable insights for ecosystem-based dynamic fishery management.展开更多
In order to study the differences in algae species and their biomass in water bodies in a region, three reservoirs and two lakes at the center of Guanzhong Plain were chosen to identify algae functional groups, measur...In order to study the differences in algae species and their biomass in water bodies in a region, three reservoirs and two lakes at the center of Guanzhong Plain were chosen to identify algae functional groups, measure biomass, and assess water quality, from January2013 to December 2014. The water bodies represented different trophic levels： one oligotrophic, three mesotrophic, and one eutrophic. Based on the Reynolds’ functional groups, they had 10 groups in common—B, P, D, X1, M, MP, F, S1, J, and G, but the algae biomasses and proportions were different. In the oligotrophic reservoir, functional group B reached a peak biomass of 576 × 104 L-1, which accounted for 31.27%. In the eutrophic lake,functional group D reached a peak biomass of 3227 × 104 L-1, which accounted for only13.38%. When samples collected from other water bodies with similar trophic levels were compared, we found differences in the algae species functional groups. The potential reasons for the differences in algae functional group characteristics in the different water bodies in the region were water temperature and nutritional states.展开更多
Stable carbon and nitrogen isotopes were used to investigate nutrient pathways and trophic relationships from the rice-crab system in Panjin, Liaoning Province, China. Values of 313C ranged from -27.38%±0.44%o to...Stable carbon and nitrogen isotopes were used to investigate nutrient pathways and trophic relationships from the rice-crab system in Panjin, Liaoning Province, China. Values of 313C ranged from -27.38%±0.44%o to -18.34%±0.26%o and δ^15N ranged from 1.10%o4-0.88%o to 9.33%±0.57%. Pseudorasbora parva （Stone moroko） had the highest δ^13C and 8tSN values. The lowest δ^13C values were obtained for the macrophytes and the lowest δ^15N value was found in sediments. Stable carbon and nitrogen isotopes were used to determine the contribution of different food items to the diets of crabs. The δ^13C results indicated that the Pseudorasbora parva made the greatest contribution to the diet of Eriocheir sinensis （Chinese mitten crab）, while the δ^15N results indicated that most food items contributed more than 10% to the diet of the crab. There were three trophic levels identified in the system （Levels 0-2）. The crab Eriocheir sinensis, fish Pseudorasbora parva and Misgurnus anguillicaudatus （Oriental weatherfish）, and the oligochaete Limnodrilus hoffmeisteri （Limnodrilus worm）, were at the second level, zooplankton were at the first level and suspended particulate matter and macrophytes were at trophic position 0.展开更多
We present here a pilot study to examine trophic level effects and migration patterns at the middle Shang Dynasty site of Xiaoshuangqiao in Henan Province using δD results combined with δ^13C and δ^15N values. A to...We present here a pilot study to examine trophic level effects and migration patterns at the middle Shang Dynasty site of Xiaoshuangqiao in Henan Province using δD results combined with δ^13C and δ^15N values. A total of 33 specimens（17 humans, 7 cattle, 5 pigs, 3 sheep, 1 dog） of bone collagen were isotopically analyzed for δ^13C, δ^15N, and dD values. A strong positive correlation（R^2 = 0.94）between mean δ^15N and δD values of herbivores（cattle and sheep）, omnivores（pig）, carnivores（dog）and humans was observed. The δD results were found to increase by -10‰ to 20‰ from herbivores to omnivores to carnivorous, evidence that collagen δD results are a useful indicator for the study of trophic levels and dietary patterns at archaeological sites. The δD results were also used to examine the origins of two different groups of individuals buried at Xiaoshuangqiao. Individuals buried in sacrificial pits of district V had mean δD values（-47.0 ± 2.9‰, n = 11） that were significantly（p =0.049） elevated compared to the people buried in the stratigraphy of district IX（-51.3 ± 3.3‰, n = 3）,indicating that they were ingesting water from different locations. In addition, the D values of the people buried in the stratigraphy were similar to the pigs（-54.5 ± 4.2‰, n = 5） at Xiaoshuangqiao,suggesting that they were most probably of the local population, and that the individuals buried in the sacrificial pits were most possibly from the coast and prisoners of the Dongyi（“东夷”）people. Thus,δD results have the potential to examine human origins and migration patterns and should be increasingly used in conjunction with δ^13C and δ^15N values at archaeological sites.展开更多
The stomach contents of 14 main invertebrates in the Huanghai Sea are analyzed. The results indicate that: (1) the examined predator species were all omnivore with wide md range, showing no obvious selection for spec...The stomach contents of 14 main invertebrates in the Huanghai Sea are analyzed. The results indicate that: (1) the examined predator species were all omnivore with wide md range, showing no obvious selection for specific fed items, (2) on the basis of their ecological habitat, the predators could be classified into 5 different types, i.e., benthoelagic and planktopelagic animals, nektopelagic and planktopelagic animals, benthopelagic animals, nektopelagic and benthopelagic animals, and nektopelagic animals and (3) the trophic level of the 11 predator species, including Crangon affinis, Palaemon gravieri, Penaeus orientalis, Trachypenaeus curvirostris, Metapenaeopsis dalei, Portunus trituberculatus, Charybdis bimaculata, Oratosquilta oratoria, Sepia andreana, Loligo beka and L. japonica ranged from 2. 30 to 2. 72, belonging to low carnivore (trophic level: 2. 0~ 2. 8), whereas that of the other 3 predator species, including Sepia esculenta, Sepiella maindroni and Todarodes pacificus were in the range of 2. 86~ 2. 97, belonging to mid-carnivore (trophic level: 2. 9 ~3. 4).展开更多
The food sources of aquacultured Apostichopus japonicus and the trophic levels of organisms in a sea cucumber（A. japonicus） and prawn（Penaeus japonica） polyculture system in a saltwater pond in Zhuanghe, Liaoning ...The food sources of aquacultured Apostichopus japonicus and the trophic levels of organisms in a sea cucumber（A. japonicus） and prawn（Penaeus japonica） polyculture system in a saltwater pond in Zhuanghe, Liaoning Province were examined using carbon and nitrogen stable isotopes. Across organisms, δ13C ranged from（–25.47±0.20）‰ to（–16.48±0.17）‰（mean±SD）, and δ15N ranged from（4.23±0.49）‰ to（12.44±0.09）‰. The δ13C and δ15N contents of A. japonicus, P. japonica and Fenneropenaeus chinensis were comparatively higher than those of other organisms. Values of δ13C and δ15N revealed that P. japonica, Hemigrapsus sanguineus and Neomysis japonica comprised the largest component of the diet of A. japonicus. The mean trophic level of the organisms in this saltwater pond polyculture system was（2.75±0.08）. P. japonica, A. japonicus, F. chinensis,Synechogobius hasta and Neomysis japonica were in the 3rd trophic level（2–3）; jellyfish, H. sanguineus and zooplankton were in the 2nd trophic level（1–2）; and Enteromorpha prolifera, benthic microalgae, periphyton and suspended matter primarily consisting of phytoplankton, bacteria and humus were in the primary trophic level（0–1）.展开更多
Fish otolithδ^(15) N(δ^(15) N_(oto))is a demonstrated source of information of dietary history for marine fi sh as it is available iN_(oto)lith archives and sedimentary deposits unlike white muscle tissue(WMT).WMT a...Fish otolithδ^(15) N(δ^(15) N_(oto))is a demonstrated source of information of dietary history for marine fi sh as it is available iN_(oto)lith archives and sedimentary deposits unlike white muscle tissue(WMT).WMT and stomach content data are insufficient for trophic level(TL)data of past fi shes which is important for the changes of marine fi shery resources over long time scales.To determine the correlation betweenδ^(15) N_(oto) and fi sh WMTδ^(15) N(δ^(15) N_(wmt))and the feasibility of usingδ^(15) N_(oto) in characterizing the TLs of marine fi shes,we conducted nitrogen stable isotope analysis(SIA)in the otolith and WMT of 36 marine fi sh species sampled from the Yellow Sea and northern East China Sea in 2011-2014.Bothδ^(15) N_(oto) andδ^(15) N_(wmt) were analyzed using an elemental analyzer coupled with an isotope ratio mass spectrometer(EA-IRMS).Multiple otoliths were combined to make each otolith measurement and were analyzed as-is without a carbonate dissolution pre-processing step.δ^(15) N_(oto) andδ^(15) N_(wmt) comparisons for species in the Yellow Sea and northern East China Sea are currently lacking and would be helpful for both regional studies and for increasing the number of species for whichδ^(15) N_(oto) andδ^(15) N_(wmt) have been compared.Additionally,to determine the relative accuracy of trophic level calculated usingδ^(15) N_(oto),we compared TL calculated fromδ^(15) N_(oto) to traditional trophic level metrics calculated usingδ^(15) N_(wmt).The results showed a positive and highly signifi cant correlation(R=0.780,P<0.001)betweenδ^(15) N_(oto) andδ^(15) N_(wmt).Trophic level estimation using WMT(TL wmt)and otolith(TL oto)showed congruence in our study,which is not entirely surprising given thatδ^(15) N_(oto) was regressed againstδ^(15) N_(wmt) and the resulting regression coefficient was used to convertδ^(15) N_(oto) toδ^(15) N_(wmt) prior to calculating TL oto.This conversion was required in order to be consistent with previousδ^(15) N_(wmt)-based calculations of TL for comparison.TL oto calculations resulted in TL values that were largely within 5%-10%of TL values calculated withδ^(15) N_(wmt).Our fi ndings show thatδ^(15) N_(oto) is a feasible technique for characterizing the TLs of marine fi sh and can also assist in food web and marine ecosystem studies.展开更多
Fishing activities can alter the structure of marine food webs by the selective removal of some species. The changes in the marine food webs of the Hormuzgan waters of the Persian Gulf, Iran were assessed, based on es...Fishing activities can alter the structure of marine food webs by the selective removal of some species. The changes in the marine food webs of the Hormuzgan waters of the Persian Gulf, Iran were assessed, based on estimates of the mean trophic index （MTI） and Fishing in Balance index （FIB）, and on landing profile of the exploited marine community （49 species） during the period, 2002-2011. The total landings （Yt） （R=0.88, P〈0.001） increased gradually while the Y~ of carnivores has slightly declined, and the Yt of herbivores, detritivores and omnivores has increased. Consequently, the MTI significantly decreased （R=-0.69, P〈0.05） at a rate of 0.1 l during this decade. The MTI showed a decreasing trend, which indicates exploitation of marine resources. The FiB index also showed a downward trend and negative values from 2002 to 2009, which may be associated with unbalanced structure in the fisheries, but an upward trend from 2009 to 20ll. The time variation of the landing profile showed two periods with significant differences in their species composition （R=0.88; P=0.005）, and based on analysis of similarity, species have been identified as discriminator species, namely Thunnus albacores and Benthosema pterotum. Results indicate that changes in MTI reflected changes in the Hormuzgan landing structure. The examination of the MTI, FBI, and landing profile （LP） temporal pattern suggests that the status of fishery resources in Hormuzgan inshore waters is overexploited, and provides evidence of the probability that a fishing down process is occurring in this area, and that this trend may continue in the long-tenn. Therefore, environmental fisheries management and conservation programs should be prioritized for these valuable resources.展开更多
You are what you eat (diet) and where you eat (trophic level) in the food web. The relative abundance of pairs of stable isotopes of the organic elements carbon (e.g., the isotope ratio of <sup>13</sup>C v...You are what you eat (diet) and where you eat (trophic level) in the food web. The relative abundance of pairs of stable isotopes of the organic elements carbon (e.g., the isotope ratio of <sup>13</sup>C vs<sup> 12</sup>C), nitrogen, and sulfur, among others, in the tissues of a consumer reflects a weighted-average of the isotope ratios in the sources it consumes, after some corrections for the processes of digestion and assimilation. We extended a Bayesian mixing model to infer trophic positions of consumer organisms in a food web in addition to the degree to which distinct resource pools (diet sources) support consumers. The novel features in this work include: 1) trophic level estimation (vertical position in foodweb) and 2) the Bayesian exposition of a biologically realistic model [1] including stable isotope ratios and concentrations of carbon, nitrogen, and sulfur, isotopic fractionations, elemental assimilation efficiencies, as well as extensive use of prior information. We discuss issues of parameter identifiability in the complex and most realistic model. We apply our model to simulated data and to bottlenose dolphins (Tursiops truncatus) feeding on several numerically abundant fish species, which in turn feed on other fish and primary producing plants and algae present in St. George Sound, FL, USA. Finally, we discuss extensions from other work that apply to this model and three important general ecological applications. Online supplementary materials include data, OpenBUGS scripts, and simulation details.展开更多
The trophic status assessment of lakes in different lake regions may provide important and fundamental information for lake trophic state classification and eutrophication control. In this study, a region-specific lak...The trophic status assessment of lakes in different lake regions may provide important and fundamental information for lake trophic state classification and eutrophication control. In this study, a region-specific lake eutrophication assessment standard was established through a frequency distribution method based on chlorophyll-a concentration. The assessment standards under the oligotrophic state for lakes in the Eastern plain, Yungui Plateau, Northeast Plain and Mountain Mongolia-Xinjiang regions are total phosphorus of 0.068, 0.005, 0.011, 0.005 mg/L; total nitrogen of 1.00, 0.16, 0.37, 0.60 mg/L; Secchi depth of 0.60, 8.00, 1.55, 3.00 m; and CODMn of 2.24, 1.00, 5.1 l, 4.00 mg/L, respectively. Moreover, a region-specific comprehensive trophic level index was developed to provide an understandable assessment method for the public. The results indicated that the frequency distribution analysis based on chlorophyll-a combined with trophic level index provided a useful metric for the assessment of the lake trophic status. In addition, the difference of eutrophication assessment standards in different lake regions was analyzed, which suggested that the sensitivities of algae to nutrients and the assessment standard of trophic status possessed significant regional differences for the four lake ecoregions. Lake eutrophication assessment standards would contribute to maximizing the effectiveness of future management strategies, to control and minimize lake eutrophication problems.展开更多
As apex predators, sharks are of ecological and conservation importance in marine ecosystems. In this study, trophic positions of sharks were estimated using stable isotope ratios of carbon and nitrogen for five repre...As apex predators, sharks are of ecological and conservation importance in marine ecosystems. In this study, trophic positions of sharks were estimated using stable isotope ratios of carbon and nitrogen for five representative species caught by the Chinese longline fleet in the mid-east Pacific, i.e., the blue shark （Prionace glauca）, the bigeye thresher shark （Alopias superciliosus）, the silky shark （Carcharhinus falciformis）, the scalloped hammerhead （Sphyrna lewini）, and the oceanic whitetip shark （Car-charhinus longimanus）. Of these species, oceanic whitetip shark has the lowest trophic level and mean 815N value （3.9 and 14.93%o± 0.84%o）, whereas bigeye thresher shark has the highest level/values （4.5 and 17.02%o±1.21%o, respectively）. The bigeye thresher shark has significantly higher 515N value than other shark species, indicating its higher trophic position. The blue shark and oceanic whitetip shark has significantly higher 813C values than bigeye thresher shark, silky shark and scalloped hammerhead, possibly due to different diets and/or living habitats. The stable isotope data and stomach content data are highly consistent, suggesting that sta-ble isotope analysis supplements traditional feeding ecology study of sharks, and thus contributes to understanding their trophic linkage.展开更多
To obtain information on food web structure in salt marshes of the Changjiang （Yangtze） River Estuary, the （ δ3C and δ15N values of primary producers and consumers were determined. The mean δ13C values of 31 d...To obtain information on food web structure in salt marshes of the Changjiang （Yangtze） River Estuary, the （ δ3C and δ15N values of primary producers and consumers were determined. The mean δ13C values of 31 dominant consumers ranged from -23.13‰ to -14.37‰. Except for several species （ Eriocheir sinensis, Sinonovacula constricta and Potamocorbula ustulata）, consumers had interme- diate δ13C values between those of benthic microalgae and Spartina alterniflora. The mean δ15N values of 31 dominant consumers varied between 6.87‰ and 13.33‰, which indicate three trophic levels in salt marshes of the Changjiang River Estuary. A total of 18 macroinvertebrates species and four fish species represented primary consumers with trophic levels ranging from 2.0 to 2.7. Secondary consumers included two maeroinvertebrates and seven fishes with trophic levels varying between 3.0 and 3.9. The consumers were divided into three trophic guilds, i.e., detritivorous/algae feeders, omnivores and carnivores. The detrital food chain was the main energy flow pathway in the salt marsh food web of the Changjiang River Estuary, and the marsh vascular plants were at least as equally important as microphytobenthos for secondary production. The important trophic function of the salt marsh habitats in the estuary is revealed.展开更多
Gaobeidian Lake, located in Beijing, China, serves as a recipient lake for efluents from a large municipal sewage treatment plant （MSTP）. In order to evaluate the effects of discharging MSTP efluent on the mercury c...Gaobeidian Lake, located in Beijing, China, serves as a recipient lake for efluents from a large municipal sewage treatment plant （MSTP）. In order to evaluate the effects of discharging MSTP efluent on the mercury contamination of the local aquatic ecosystem, sediment cores, water, plankton, fish, and turtle samples were collected from Gaobeidian Lake for mercury speciation analysis. High concentrations of total mercury （T-Hg） were detected in sediment cores （5.24–17.0 μg/g dry weight （dw）, average： 10.1 μg/g）. The ratio of methylmercury （MeHg） to T-Hg was less than 0.3% in sediments and ranged from 35% to 76% in biota samples. The highest level of T-Hg and MeHg were found in aquatic bryophyte and crucian carp （3673 and 437 ng/g dw, respectively）. The relative contents of MeHg were significantly correlated with trophic levels （R2 = 0.5506, p 0.001）, which confirmed that MeHg can be bio-transferred and biomagnified via food chain in this aquatic ecosystem.展开更多
Introduction The health benefits of consuming aquatic organisms are clear,given their high protein count,low saturated fats,and low cholesterol content.Fish,in particular,contains valuable nutrients(e.g.,omega-3 polyu...Introduction The health benefits of consuming aquatic organisms are clear,given their high protein count,low saturated fats,and low cholesterol content.Fish,in particular,contains valuable nutrients(e.g.,omega-3 polyunsaturated fats),vitamins,essential elements,and is therefore considered an important part of a balanced human diet.China is a major seafood producer,accounting for 58%of global production in 2018(Crona et al.,2020).China is the largest seafood consuming country in the world,with consumption rates steadily increasing.Since the 1978 Chinese economic reform,the amount of seafood consumed per capita in China increased from 5 kg per capita in 1980 to 41 kg in 2015(Zhang et al.,2021).By 2030,the overall amount of fish consumption will likely exceed the amount of fish production in China.展开更多
Quantification of water quality (WQ) is an integral part of scientifically based water resources management. The main objective of this study was comparative analysis of two approaches applied for quantitative assessm...Quantification of water quality (WQ) is an integral part of scientifically based water resources management. The main objective of this study was comparative analysis of two approaches applied for quantitative assessment of WQ: the trophic level index (TLI) and the Delphi method (DM). We analyzed the following features of these conceptually different approaches: A. similarity of estimates of lake WQ;B. sensitivity to indicating disturbances in the aquatic ecosystem structure and functioning;C. capacity to reflect the impact of major management measures on the quality of water resources. We compared the DM and TLI based on results from a series of lakes covering varying productivity levels, mixing regimes and climatic zones. We assumed that the conservation of aquatic ecosystem in some predefined, “reference”, state is a major objective of sustainable water resources management in the study lakes. The comparison between the two approaches was quantified as a relationship between the DM ranks and respective TLI values. We show that being a classification system, the TLI does not account for specific characteristics of aquatic ecosystems and the array of different potential uses of the water resource. It indirectly assumes that oligotrophication is identical to WQ improvement, and reduction of economic activity within the lake catchment area is the most effective way to improve WQ. WQ assessed with the TLI is more suitable for needs of natural water resources management if eutrophication is a major threat. The DM allows accounting for several water resource uses and therefore it may serve as a more robust and comprehensive tool for WQ quantification and thus for sustainable water resources management.展开更多
基金supported by the Scientific Research Foundation of Hainan Tropical Ocean University(No.RHDRC202312)the Major Science and Technology Project of Yazhou Bay Innovation Institute of Hainan Tropical Ocean University:Research on Hainan Coastal Marine Ecological Environment and Carbon Sink(No.2022CXYZD002).
文摘Fish scaleδ^(15)N(δ^(15)N_(sca))records trophic information of the whole life history for marine fishes.Data from gut content and values calculated from white muscle tissue(WMT)are insufficient for assessing trophic level(TL)of marine fishes as they only provide the information of several months or even several days.Stable isotope analysis(SIA)of nitrogen was carried out in fish scales and WMT of 16 species from a total of 28 individuals captured from the Yellow Sea and northern East China Sea in October and November of 2019,aiming at discovering the correlation betweenδ^(15)N_(sca) and fish WMTδ^(15)N(δ^(15)NWMT),so as to useδ^(15)N_(sca) for the characterization of TLs of marine fish.Scales were analyzed without prior carbonate dissolution as a pre-processing step.TL calculated fromδ^(15)N_(sca) was compared to traditional TL formula calculated withδ^(15)N_(WMT) to estimate the accuracy.We found that there was a highly significant and positive correlation(r=0.830,P<0.001)betweenδ^(15)N_(sca) andδ^(15)N_(WMT).TL calculation results using fish scale(TL_(sca))and WMT(TL_(WMT))showed congruence(r=0.773,P<0.001),and the regression coefficient betweenδ^(15)N_(sca) andδ^(15)NWMT was used for calculating TLsca.The conversion was conducted for the purpose of comparison with previousδ^(15)N_(WMT)-based calculation results of TL.TLsca calculation results were 81.25%within the TL range of±10%calculated withδ^(15)NWMT.The findings in the present study showed thatδ^(15)N_(sca) is a viable technique for the characterization of the TL of marine fish and can help to predict food web and support the study of marine ecosystem.
基金The National Key Research and Development Program of China under contract No.2023YFD2401303.
文摘Understanding the catch composition of multispecies fisheries is fundamental to effective spatial fishery management.In the Equatorial Western and Central Pacific Ocean(EWCPO),the main catches of the tuna purse-seine fishery include skipjack tuna(Katsuwonus pelamis),yellowfin tuna(Thunnus albacares),and bigeye tuna(Thunnus obesus).Studying the spatiotemporal distribution of the catch composition in the context of climate change contributes to the sustainable development of this fishery.Our study analyzed purse seine fishery data and environmental data from 1997 to 2019,using a random forest model to explore the changing mechanisms of catch composition under different El Niño-Southern Oscillation(ENSO)episodes with catch mean trophic level(CMTL)as the response variable.Emerging hot spot analysis was used to identify significant spatiotemporal hot(cold)spot areas.The results revealed two hot spot areas,namely the western hotspot area(WHA)and the eastern hotspot area(EHA),and two cold spot areas,namely the northern cold spot area(NCA)and the southern cold spot area(SCA).EHA spans the entire central Pacific east of 170°E among different ENSO episodes,expanding and contracting in tandem with the 28℃isotherm.WHA is mainly influenced by surface organic matter and the Western Boundary Currents and remains among different ENSO episodes.NCA is formed by the westerly anomalies and positive wind stress curl anomalies and exists only under La Niña episodes.SCA persists within the unproductive South Equatorial Current(SEC)and remains stable among different ENSO episodes.Our study contributes to revealing the spatiotemporal dynamics in tuna catch composition and their relationships with environmental factors and interspecies competition,providing valuable insights for ecosystem-based dynamic fishery management.
基金supported by the Ministry of Human Resources and Social Security of the People's Republic of China,Shaanxi Youth Science and Technology Star Project(No.2012KJXX-32)the National Natural Science Youth Fund(No.51008242)
文摘In order to study the differences in algae species and their biomass in water bodies in a region, three reservoirs and two lakes at the center of Guanzhong Plain were chosen to identify algae functional groups, measure biomass, and assess water quality, from January2013 to December 2014. The water bodies represented different trophic levels： one oligotrophic, three mesotrophic, and one eutrophic. Based on the Reynolds’ functional groups, they had 10 groups in common—B, P, D, X1, M, MP, F, S1, J, and G, but the algae biomasses and proportions were different. In the oligotrophic reservoir, functional group B reached a peak biomass of 576 × 104 L-1, which accounted for 31.27%. In the eutrophic lake,functional group D reached a peak biomass of 3227 × 104 L-1, which accounted for only13.38%. When samples collected from other water bodies with similar trophic levels were compared, we found differences in the algae species functional groups. The potential reasons for the differences in algae functional group characteristics in the different water bodies in the region were water temperature and nutritional states.
基金Supported by the National Special Research Fund for Non-Profit Sector(Agriculture)(No.201203O81-7)
文摘Stable carbon and nitrogen isotopes were used to investigate nutrient pathways and trophic relationships from the rice-crab system in Panjin, Liaoning Province, China. Values of 313C ranged from -27.38%±0.44%o to -18.34%±0.26%o and δ^15N ranged from 1.10%o4-0.88%o to 9.33%±0.57%. Pseudorasbora parva （Stone moroko） had the highest δ^13C and 8tSN values. The lowest δ^13C values were obtained for the macrophytes and the lowest δ^15N value was found in sediments. Stable carbon and nitrogen isotopes were used to determine the contribution of different food items to the diets of crabs. The δ^13C results indicated that the Pseudorasbora parva made the greatest contribution to the diet of Eriocheir sinensis （Chinese mitten crab）, while the δ^15N results indicated that most food items contributed more than 10% to the diet of the crab. There were three trophic levels identified in the system （Levels 0-2）. The crab Eriocheir sinensis, fish Pseudorasbora parva and Misgurnus anguillicaudatus （Oriental weatherfish）, and the oligochaete Limnodrilus hoffmeisteri （Limnodrilus worm）, were at the second level, zooplankton were at the first level and suspended particulate matter and macrophytes were at trophic position 0.
基金supported by the National Natural Science Foundation of China(Grant No.41603009)MOE(Ministry of Education in China) Project of Humanities and Social Sciences(No.16YJCZH100)+1 种基金Origin of Chinese Civilisation and Mount Songshan Civilisation Zhengzhou Research Association(No.Q2015-1)Humanities and Social Science Research Foundation of Jiangsu Normal University(No.15XWR025)
文摘We present here a pilot study to examine trophic level effects and migration patterns at the middle Shang Dynasty site of Xiaoshuangqiao in Henan Province using δD results combined with δ^13C and δ^15N values. A total of 33 specimens（17 humans, 7 cattle, 5 pigs, 3 sheep, 1 dog） of bone collagen were isotopically analyzed for δ^13C, δ^15N, and dD values. A strong positive correlation（R^2 = 0.94）between mean δ^15N and δD values of herbivores（cattle and sheep）, omnivores（pig）, carnivores（dog）and humans was observed. The δD results were found to increase by -10‰ to 20‰ from herbivores to omnivores to carnivorous, evidence that collagen δD results are a useful indicator for the study of trophic levels and dietary patterns at archaeological sites. The δD results were also used to examine the origins of two different groups of individuals buried at Xiaoshuangqiao. Individuals buried in sacrificial pits of district V had mean δD values（-47.0 ± 2.9‰, n = 11） that were significantly（p =0.049） elevated compared to the people buried in the stratigraphy of district IX（-51.3 ± 3.3‰, n = 3）,indicating that they were ingesting water from different locations. In addition, the D values of the people buried in the stratigraphy were similar to the pigs（-54.5 ± 4.2‰, n = 5） at Xiaoshuangqiao,suggesting that they were most probably of the local population, and that the individuals buried in the sacrificial pits were most possibly from the coast and prisoners of the Dongyi（“东夷”）people. Thus,δD results have the potential to examine human origins and migration patterns and should be increasingly used in conjunction with δ^13C and δ^15N values at archaeological sites.
文摘The stomach contents of 14 main invertebrates in the Huanghai Sea are analyzed. The results indicate that: (1) the examined predator species were all omnivore with wide md range, showing no obvious selection for specific fed items, (2) on the basis of their ecological habitat, the predators could be classified into 5 different types, i.e., benthoelagic and planktopelagic animals, nektopelagic and planktopelagic animals, benthopelagic animals, nektopelagic and benthopelagic animals, and nektopelagic animals and (3) the trophic level of the 11 predator species, including Crangon affinis, Palaemon gravieri, Penaeus orientalis, Trachypenaeus curvirostris, Metapenaeopsis dalei, Portunus trituberculatus, Charybdis bimaculata, Oratosquilta oratoria, Sepia andreana, Loligo beka and L. japonica ranged from 2. 30 to 2. 72, belonging to low carnivore (trophic level: 2. 0~ 2. 8), whereas that of the other 3 predator species, including Sepia esculenta, Sepiella maindroni and Todarodes pacificus were in the range of 2. 86~ 2. 97, belonging to mid-carnivore (trophic level: 2. 9 ~3. 4).
基金The National Marine Public Welfare Project of China under contract No.201305005
文摘The food sources of aquacultured Apostichopus japonicus and the trophic levels of organisms in a sea cucumber（A. japonicus） and prawn（Penaeus japonica） polyculture system in a saltwater pond in Zhuanghe, Liaoning Province were examined using carbon and nitrogen stable isotopes. Across organisms, δ13C ranged from（–25.47±0.20）‰ to（–16.48±0.17）‰（mean±SD）, and δ15N ranged from（4.23±0.49）‰ to（12.44±0.09）‰. The δ13C and δ15N contents of A. japonicus, P. japonica and Fenneropenaeus chinensis were comparatively higher than those of other organisms. Values of δ13C and δ15N revealed that P. japonica, Hemigrapsus sanguineus and Neomysis japonica comprised the largest component of the diet of A. japonicus. The mean trophic level of the organisms in this saltwater pond polyculture system was（2.75±0.08）. P. japonica, A. japonicus, F. chinensis,Synechogobius hasta and Neomysis japonica were in the 3rd trophic level（2–3）; jellyfish, H. sanguineus and zooplankton were in the 2nd trophic level（1–2）; and Enteromorpha prolifera, benthic microalgae, periphyton and suspended matter primarily consisting of phytoplankton, bacteria and humus were in the primary trophic level（0–1）.
基金Supported by the National Key Basic Research Development Program of China(973 Program)(No.2015CB453303)the National Science Foundation for Young Scientists of China(No.41606195)。
文摘Fish otolithδ^(15) N(δ^(15) N_(oto))is a demonstrated source of information of dietary history for marine fi sh as it is available iN_(oto)lith archives and sedimentary deposits unlike white muscle tissue(WMT).WMT and stomach content data are insufficient for trophic level(TL)data of past fi shes which is important for the changes of marine fi shery resources over long time scales.To determine the correlation betweenδ^(15) N_(oto) and fi sh WMTδ^(15) N(δ^(15) N_(wmt))and the feasibility of usingδ^(15) N_(oto) in characterizing the TLs of marine fi shes,we conducted nitrogen stable isotope analysis(SIA)in the otolith and WMT of 36 marine fi sh species sampled from the Yellow Sea and northern East China Sea in 2011-2014.Bothδ^(15) N_(oto) andδ^(15) N_(wmt) were analyzed using an elemental analyzer coupled with an isotope ratio mass spectrometer(EA-IRMS).Multiple otoliths were combined to make each otolith measurement and were analyzed as-is without a carbonate dissolution pre-processing step.δ^(15) N_(oto) andδ^(15) N_(wmt) comparisons for species in the Yellow Sea and northern East China Sea are currently lacking and would be helpful for both regional studies and for increasing the number of species for whichδ^(15) N_(oto) andδ^(15) N_(wmt) have been compared.Additionally,to determine the relative accuracy of trophic level calculated usingδ^(15) N_(oto),we compared TL calculated fromδ^(15) N_(oto) to traditional trophic level metrics calculated usingδ^(15) N_(wmt).The results showed a positive and highly signifi cant correlation(R=0.780,P<0.001)betweenδ^(15) N_(oto) andδ^(15) N_(wmt).Trophic level estimation using WMT(TL wmt)and otolith(TL oto)showed congruence in our study,which is not entirely surprising given thatδ^(15) N_(oto) was regressed againstδ^(15) N_(wmt) and the resulting regression coefficient was used to convertδ^(15) N_(oto) toδ^(15) N_(wmt) prior to calculating TL oto.This conversion was required in order to be consistent with previousδ^(15) N_(wmt)-based calculations of TL for comparison.TL oto calculations resulted in TL values that were largely within 5%-10%of TL values calculated withδ^(15) N_(wmt).Our fi ndings show thatδ^(15) N_(oto) is a feasible technique for characterizing the TLs of marine fi sh and can also assist in food web and marine ecosystem studies.
文摘Fishing activities can alter the structure of marine food webs by the selective removal of some species. The changes in the marine food webs of the Hormuzgan waters of the Persian Gulf, Iran were assessed, based on estimates of the mean trophic index （MTI） and Fishing in Balance index （FIB）, and on landing profile of the exploited marine community （49 species） during the period, 2002-2011. The total landings （Yt） （R=0.88, P〈0.001） increased gradually while the Y~ of carnivores has slightly declined, and the Yt of herbivores, detritivores and omnivores has increased. Consequently, the MTI significantly decreased （R=-0.69, P〈0.05） at a rate of 0.1 l during this decade. The MTI showed a decreasing trend, which indicates exploitation of marine resources. The FiB index also showed a downward trend and negative values from 2002 to 2009, which may be associated with unbalanced structure in the fisheries, but an upward trend from 2009 to 20ll. The time variation of the landing profile showed two periods with significant differences in their species composition （R=0.88; P=0.005）, and based on analysis of similarity, species have been identified as discriminator species, namely Thunnus albacores and Benthosema pterotum. Results indicate that changes in MTI reflected changes in the Hormuzgan landing structure. The examination of the MTI, FBI, and landing profile （LP） temporal pattern suggests that the status of fishery resources in Hormuzgan inshore waters is overexploited, and provides evidence of the probability that a fishing down process is occurring in this area, and that this trend may continue in the long-tenn. Therefore, environmental fisheries management and conservation programs should be prioritized for these valuable resources.
文摘You are what you eat (diet) and where you eat (trophic level) in the food web. The relative abundance of pairs of stable isotopes of the organic elements carbon (e.g., the isotope ratio of <sup>13</sup>C vs<sup> 12</sup>C), nitrogen, and sulfur, among others, in the tissues of a consumer reflects a weighted-average of the isotope ratios in the sources it consumes, after some corrections for the processes of digestion and assimilation. We extended a Bayesian mixing model to infer trophic positions of consumer organisms in a food web in addition to the degree to which distinct resource pools (diet sources) support consumers. The novel features in this work include: 1) trophic level estimation (vertical position in foodweb) and 2) the Bayesian exposition of a biologically realistic model [1] including stable isotope ratios and concentrations of carbon, nitrogen, and sulfur, isotopic fractionations, elemental assimilation efficiencies, as well as extensive use of prior information. We discuss issues of parameter identifiability in the complex and most realistic model. We apply our model to simulated data and to bottlenose dolphins (Tursiops truncatus) feeding on several numerically abundant fish species, which in turn feed on other fish and primary producing plants and algae present in St. George Sound, FL, USA. Finally, we discuss extensions from other work that apply to this model and three important general ecological applications. Online supplementary materials include data, OpenBUGS scripts, and simulation details.
基金supported by the Mega-projects of Science Research for Water Environment Improvement (No.2009ZX07106-0012012ZX07101-002)+1 种基金the National Natural Science Foundation of China (No.40901248)the China Environmental Public Welfare Program (No.2010009032)
文摘The trophic status assessment of lakes in different lake regions may provide important and fundamental information for lake trophic state classification and eutrophication control. In this study, a region-specific lake eutrophication assessment standard was established through a frequency distribution method based on chlorophyll-a concentration. The assessment standards under the oligotrophic state for lakes in the Eastern plain, Yungui Plateau, Northeast Plain and Mountain Mongolia-Xinjiang regions are total phosphorus of 0.068, 0.005, 0.011, 0.005 mg/L; total nitrogen of 1.00, 0.16, 0.37, 0.60 mg/L; Secchi depth of 0.60, 8.00, 1.55, 3.00 m; and CODMn of 2.24, 1.00, 5.1 l, 4.00 mg/L, respectively. Moreover, a region-specific comprehensive trophic level index was developed to provide an understandable assessment method for the public. The results indicated that the frequency distribution analysis based on chlorophyll-a combined with trophic level index provided a useful metric for the assessment of the lake trophic status. In addition, the difference of eutrophication assessment standards in different lake regions was analyzed, which suggested that the sensitivities of algae to nutrients and the assessment standard of trophic status possessed significant regional differences for the four lake ecoregions. Lake eutrophication assessment standards would contribute to maximizing the effectiveness of future management strategies, to control and minimize lake eutrophication problems.
基金Li Yunkai was supported by the National Natural Science Foundation of China (No.41206124)Ph.D.Programs Foundation of Ministry of Education of China (No.201 23104120001)+3 种基金the ‘Chen Guang’ Project of Shanghai Municipal Education Commission (No.D8004-10-0206)the Shanghai Education Development Foundation (No.B-8102-10-0084)Zhu Jiangfeng and Dai Xiaojie were supported by the National Natural Science Foundation of China (No.41106118)the Scientific Observing and Experimental Station of Oceanic Fishery Resources, Ministry of Agriculture, China
文摘As apex predators, sharks are of ecological and conservation importance in marine ecosystems. In this study, trophic positions of sharks were estimated using stable isotope ratios of carbon and nitrogen for five representative species caught by the Chinese longline fleet in the mid-east Pacific, i.e., the blue shark （Prionace glauca）, the bigeye thresher shark （Alopias superciliosus）, the silky shark （Carcharhinus falciformis）, the scalloped hammerhead （Sphyrna lewini）, and the oceanic whitetip shark （Car-charhinus longimanus）. Of these species, oceanic whitetip shark has the lowest trophic level and mean 815N value （3.9 and 14.93%o± 0.84%o）, whereas bigeye thresher shark has the highest level/values （4.5 and 17.02%o±1.21%o, respectively）. The bigeye thresher shark has significantly higher 515N value than other shark species, indicating its higher trophic position. The blue shark and oceanic whitetip shark has significantly higher 813C values than bigeye thresher shark, silky shark and scalloped hammerhead, possibly due to different diets and/or living habitats. The stable isotope data and stomach content data are highly consistent, suggesting that sta-ble isotope analysis supplements traditional feeding ecology study of sharks, and thus contributes to understanding their trophic linkage.
基金The Science and Technology Department of Shanghai under contract Nos 08231200705, 07DZ12038 and 072312032the National Natural Science Foundation of China under contract No. 40876044
文摘To obtain information on food web structure in salt marshes of the Changjiang （Yangtze） River Estuary, the （ δ3C and δ15N values of primary producers and consumers were determined. The mean δ13C values of 31 dominant consumers ranged from -23.13‰ to -14.37‰. Except for several species （ Eriocheir sinensis, Sinonovacula constricta and Potamocorbula ustulata）, consumers had interme- diate δ13C values between those of benthic microalgae and Spartina alterniflora. The mean δ15N values of 31 dominant consumers varied between 6.87‰ and 13.33‰, which indicate three trophic levels in salt marshes of the Changjiang River Estuary. A total of 18 macroinvertebrates species and four fish species represented primary consumers with trophic levels ranging from 2.0 to 2.7. Secondary consumers included two maeroinvertebrates and seven fishes with trophic levels varying between 3.0 and 3.9. The consumers were divided into three trophic guilds, i.e., detritivorous/algae feeders, omnivores and carnivores. The detrital food chain was the main energy flow pathway in the salt marsh food web of the Changjiang River Estuary, and the marsh vascular plants were at least as equally important as microphytobenthos for secondary production. The important trophic function of the salt marsh habitats in the estuary is revealed.
基金supported by the ChineseAcademy of Sciences (No kzcx1-yw-06-03, KJCX2-YW-H04)the National Natural Science Foundation of China (No 20707033)
文摘Gaobeidian Lake, located in Beijing, China, serves as a recipient lake for efluents from a large municipal sewage treatment plant （MSTP）. In order to evaluate the effects of discharging MSTP efluent on the mercury contamination of the local aquatic ecosystem, sediment cores, water, plankton, fish, and turtle samples were collected from Gaobeidian Lake for mercury speciation analysis. High concentrations of total mercury （T-Hg） were detected in sediment cores （5.24–17.0 μg/g dry weight （dw）, average： 10.1 μg/g）. The ratio of methylmercury （MeHg） to T-Hg was less than 0.3% in sediments and ranged from 35% to 76% in biota samples. The highest level of T-Hg and MeHg were found in aquatic bryophyte and crucian carp （3673 and 437 ng/g dw, respectively）. The relative contents of MeHg were significantly correlated with trophic levels （R2 = 0.5506, p 0.001）, which confirmed that MeHg can be bio-transferred and biomagnified via food chain in this aquatic ecosystem.
基金This work was supported by the Natural Sciences and Engineering Research Council of Canada,the Canadian Institutes of Health Research,and Alberta Health.
文摘Introduction The health benefits of consuming aquatic organisms are clear,given their high protein count,low saturated fats,and low cholesterol content.Fish,in particular,contains valuable nutrients(e.g.,omega-3 polyunsaturated fats),vitamins,essential elements,and is therefore considered an important part of a balanced human diet.China is a major seafood producer,accounting for 58%of global production in 2018(Crona et al.,2020).China is the largest seafood consuming country in the world,with consumption rates steadily increasing.Since the 1978 Chinese economic reform,the amount of seafood consumed per capita in China increased from 5 kg per capita in 1980 to 41 kg in 2015(Zhang et al.,2021).By 2030,the overall amount of fish consumption will likely exceed the amount of fish production in China.
文摘Quantification of water quality (WQ) is an integral part of scientifically based water resources management. The main objective of this study was comparative analysis of two approaches applied for quantitative assessment of WQ: the trophic level index (TLI) and the Delphi method (DM). We analyzed the following features of these conceptually different approaches: A. similarity of estimates of lake WQ;B. sensitivity to indicating disturbances in the aquatic ecosystem structure and functioning;C. capacity to reflect the impact of major management measures on the quality of water resources. We compared the DM and TLI based on results from a series of lakes covering varying productivity levels, mixing regimes and climatic zones. We assumed that the conservation of aquatic ecosystem in some predefined, “reference”, state is a major objective of sustainable water resources management in the study lakes. The comparison between the two approaches was quantified as a relationship between the DM ranks and respective TLI values. We show that being a classification system, the TLI does not account for specific characteristics of aquatic ecosystems and the array of different potential uses of the water resource. It indirectly assumes that oligotrophication is identical to WQ improvement, and reduction of economic activity within the lake catchment area is the most effective way to improve WQ. WQ assessed with the TLI is more suitable for needs of natural water resources management if eutrophication is a major threat. The DM allows accounting for several water resource uses and therefore it may serve as a more robust and comprehensive tool for WQ quantification and thus for sustainable water resources management.
