Blooms of the toxic dinoflagellate Alexandrium spp.,which produce paralytic shellfish toxins(PSTs),have threatened marine ecosystems for decades.However,their impacts on benthic copepods remain underexplored.Here,we i...Blooms of the toxic dinoflagellate Alexandrium spp.,which produce paralytic shellfish toxins(PSTs),have threatened marine ecosystems for decades.However,their impacts on benthic copepods remain underexplored.Here,we investigated the physiological and biochemical responses of marine benthic copepod Tigriopus japonicus to Alexandrium pacificum.Adult female showed no mortality within 24 h and maintained high survival(>80%)across all A.pacificum concentrations over 96 h,with no significant difference from non-toxic controls.Ingestion rates on A.pacificum and non-toxic controls were similar,when algal prey concentrations were lower than about 2500µgC/L.However,above this threshold,feeding of T.japonicus was significantly depressed by A.pacificum.Six-day exposure induced oxidative stress,marked by elevated level of reactive oxygen species,malondialdehyde,total antioxidant capacity and superoxide dismutase activity,while catalase activity showed a non-significant increase.Moreover,concentration-dependent increase was observed in acetylcholinesterase activity,and its positive correlation with oxidative biomarkers suggests additional roles in coping with stress.Chronic exposure over three generations did not consistently affect development,except for complete development failure in F2 and F3 at the highest concentration.However,moderate-to-high concentrations of A.pacificum significantly impaired reproduction,reducing egg production by 9.66%–96.07%and clutch numbers by 33.33%–55.56%.Our findings indicate that Alexandrium blooms can adversely impact benthic copepod feeding and population recruitment through neurotoxicity and oxidative stress,highlighting the ecological risks of prolonged algal blooms in benthic habitats.展开更多
The spatial variability of mesozooplankton(MZ)community characteristics,with an emphasis on the predominant taxa,copepods,were evaluated between two distinct coastal water environments of Mangalore:the Netravati-Gurup...The spatial variability of mesozooplankton(MZ)community characteristics,with an emphasis on the predominant taxa,copepods,were evaluated between two distinct coastal water environments of Mangalore:the Netravati-Gurupura estuarine system(NGES)and the adjacent nearshore waters(<20 m depth)on the southwest coast of India during winter 2018.The nearshore waters were characterised by uniformly distributed hydrographic properties,particularly in terms of water column temperature,salinity and turbidity.This well-mixed water column likely stimulated increased phytoplankton chlorophyll a concentrations[av.(2.9±2.2)mg/m^(3)],which in turn supported higher MZ biomass[av.(0.4±0.15)mL/m^(3)]and abundance[av.(6889±3387)ind./m^(3)]in the nearshore waters.In contrast,the NGES exhibited highly variable hydrographic conditions,leading to inconsistent chlorophyll a[av.(3.2±3.7)mg/m^(3)],along with significantly lower MZ biomass[av.(0.1±0.2)mL/m^(3)]and abundance[av.(238±339)ind./m^(3)].The MZ community was dominated by herbivorous copepods(HCs),particularly Bestiolina similis,in the entire study region;however,the nearshore waters supported a more diverse taxon.The overall dominance of HCs,e.g.,B.similis and Pseudodiaptomous aurivillii,in the nearshore waters,indicates the presence of stable hydrographic conditions,especially consistently higher salinity and chlorophyll a level.In contrast,the unstable hydrographic conditions in the NGES,primarily reflected in the uneven salinity distributions,likely contributed to the reduced MZ biomass and abundance.The relative increase in the abundance of B.similis observed exclusively in the euhaline zones of the estuary highlights the significant influence of neritic waters.展开更多
Silicon limitation negatively affects the growth and metabolism of diatoms.However,its influence on the topography and mechanical properties of diatom frustules,and consequently on predation,remains unclear.We investi...Silicon limitation negatively affects the growth and metabolism of diatoms.However,its influence on the topography and mechanical properties of diatom frustules,and consequently on predation,remains unclear.We investigated how silicon limitation affects the mechanical strength of diatom frustules.Under silicon limitation,the growth rates of diatom Cylindrotheca closterium,Amphora coffeaeformis,Thalassiosira weissflogii,and Cyclotella sp.decreased by 19%,56%,42%,and 73%,respectively.Similarly,the biogenic silica content of silicon-limited C.closterium,T.weissflogii,and Cyclotella sp.decreased by 17%,11%,and 9%,respectively,whereas A.coffeaeformis showed a 63%increase.Atomic force microscopy and X-ray photoelectron spectroscopy revealed that silicon shortage reduced frustule hardness by approximately 60%and decreased condensed silica components on their surface by about 80%,except in A.coffeaeformis.Additionally,copepods consumed 20%to 600%more diatoms grown under silicon deficiency compared to those grown under Si-rich conditions,with the exception of A.coffeaeformis.These findings suggest that silicon limitation diminishes diatom populations and accelerates carbon export from diatoms to the deep sea.展开更多
In the paper,copepod universal formulas are applied to construct a copepod individual-based model(IBM),and a genetic algorithm(GA)is incorporated in the formulas with genes as species parameters.The IBM initially cons...In the paper,copepod universal formulas are applied to construct a copepod individual-based model(IBM),and a genetic algorithm(GA)is incorporated in the formulas with genes as species parameters.The IBM initially constructs the individuals with all possible genes similar to the original state of natural selection.Climate-averaged temperature and chlorophyll a(Chl a)time series at the surface layer of fixed points in the Georges Bank(GB)and the Gulf of Maine(GOM)are taken as the model environment.The IBM has been running for 50 a in the environment without inter-annual change.The IBM results indicate that some of the life history traits of the top ten abundant species output by the IBM in the GB and the GOM are consistent with the real species Calanus finmarchicus,Pseudocalanus spp.,Centropages typicus,and Centropages hamatus in terms of reproduction strategy,time to reach the maximum abundance,water temperature preference,and adult body mass.The study of the top ten abundant species with multidimensional scaling(MDS)and clustering analysis(CA)methods indicates that reproduction strategy is the basis for grouping.For the species taking the broadcasting strategy,both GB and GOM environments tend to choose smallbodied species with cold-water preference,such as Pseudocalanus spp.;for the species taking the egg-carrying strategies,the GB environment selects large-bodied species with cold-water preference,such as C.finmarchicus,while the GOM environment selects medium-bodied species with warm-water preference,such as Centropages spp.(C.typicus and C.hamatus).After gene mutation is added to the IBM,the model result gets simple,which needs to be further improved.The significance of the paper lies in systematically studying the impact of GB and GOM environments on the evolutionary life history traits of copepods for the first time.展开更多
Differences among species in prosome length and in species' response to environmental factors do exist. Therefore, it is useful to examine prosome length for different copepod species in variable environments. Sea...Differences among species in prosome length and in species' response to environmental factors do exist. Therefore, it is useful to examine prosome length for different copepod species in variable environments. Seasonal variations in prosome length of four small copepods and their copepodite stages in the Jiaozhou Bay were compared and the relative influence of temperature, salinity, and chlorophyll concentration were examined. Two peaks were found in the mean prosome length of Paracalanus parvus (in early winter and May). For Acartia bifilosa, the maximum values of all copepodites occurred mainly from February to April, and decreased to the bottom in July. Prosome length of Acartia pacifica peaked when it first appeared in June, then reached to the minimum in July. Parvocalanus crassirostris only appeared from late summer to autumn and the mean prosome length showed no clear changes. Correlations of adult prosome length with environmental factors were evaluated. For the four species, temperature was negatively correlated to prosome length except for P. crassirostris. But the different species varied markedly in their responds to temperature. A. bifilosa showed a more definite trend of size variation with temperature than P. parvus and A. pacifica. Correlations of prosome length with salinity were significantly positive for almost all the small copepods. The relationship between chlorophyll concentration and prosome length was complicated for these copepods, but for P. parvus, chlorophyll concentration was also an important affecting factor. Furthermore, investigation needs to be done on food quality for some copepod. These results are essential to estimate the biomass and the production, and to understand these small copepods' population dynamics in this human-affected bay.展开更多
Planktonic copepod Calanus sinicus is the dominant meso-zooplankton in the Northwest Pacific Ocean. To better understand its population dynamics and phylogeographic patterns, 243 C. sinicus individuals were collected ...Planktonic copepod Calanus sinicus is the dominant meso-zooplankton in the Northwest Pacific Ocean. To better understand its population dynamics and phylogeographic patterns, 243 C. sinicus individuals were collected from seven locations across the shelf waters of China and its population genetics was studied by mitochondrial DNA cytochrome oxidase I（mtCOI） sequences analyses. Thirty-nine different sequences, or haplotypes, were detected with moderate haplotype diversity（h=0.749） and low nucleotide diversity（π=0.003） for all populations. The evolutionary divergence between geographic populations varied from 0.24% to 0.37%, indicative of very limited genetic differentiation. Visualized minimum spanning network（MSN） and phylogenetic analysis of all the detected haplotypes did not reveal any clear phylogeographic pattern. Furthermore, AMOVA data showed no significant spatial population differentiation existed among the individuals collected across China shelf waters. Pairwise FST values showed that population collected from northwest of the East China Sea（ECS） displayed a low difference to other populations. Mismatch distribution analyses and neutrality tests indicated that C. sinicus might undergo a demographic/population expansion. No significant population genetic structuring was detected, indicating an extensive gene flow among the C. sinicus populations. Our results provide molecular evidence for the hypothesis that C. sinicus in the northwestern South China Sea in winter is transported from the East China Sea and the Yellow Sea by the China Coastal Current during the northeast monsoon period.展开更多
Paracalanus parvus, Paracalanus crassirostris , and Acartia bifilosa are dominant and widely distributed in the Bohai Sea, and comprise an important part of zooplankton in terms of biomass as well as production rate. ...Paracalanus parvus, Paracalanus crassirostris , and Acartia bifilosa are dominant and widely distributed in the Bohai Sea, and comprise an important part of zooplankton in terms of biomass as well as production rate. In order to understand their seasonal distribution and population dynamics, their stage specific abundance in different months of the year were analyzed based on the never analyzed yet samples collected in 1959. The three species showed clear and remarkable seasonal variation in abundance, which maximized in spring and summer, when they formed high biomass patches or concentrations in the nearshore area. For Paracalanus parvus , two peaks were observed in the annual circle, one in June and the other in September. For Paracalanus crassirostris , one peak occurred in summer and a small one in December. The seasonal pattern of Acartia bifilosa was different in different regions. In Bohai Bay it had a two peak pattern, with the first large peak occurring in May and the second one in October. In Laizhou Bay, a winter peak in December and January could be observed besides the spring one. The number of generations during the reproductive season for the three species was estimated based on the annual cycle in abundance and ambient temperature.展开更多
Ecological experiments were conducted to examine the effects of seawater containing elevated par- tial pressure of carbon dioxide （p CO2 800 × 10 -6 , 2 000 × 10 -6 , 5 000 × 10 -6 and 10 000 × 10...Ecological experiments were conducted to examine the effects of seawater containing elevated par- tial pressure of carbon dioxide （p CO2 800 × 10 -6 , 2 000 × 10 -6 , 5 000 × 10 -6 and 10 000 × 10 -6 ） on the survival and reproduction of female Acartia pacifica, Acartia spinicauda, Calanus sinicus and Centropages tenuiremis, which are the dominant copepods in the southern coastal waters of China. The results show that the effects of elevated p CO2 on the survival rates of copepods were species-specific. C. sinicus, which was a macro-copepod, had a higher survival rate （62.01%–71.96%） than the other three species （5.00%–26.67%） during the eight day exposure. The egg production rates of C. sinicus, A. spinicauda and C. tenuiremis were significantly inhibited by the increased p CO2 and the exposure time duration. There were significantly negative impacts on the egg hatching success of A. spinicauda and C. tenuiremis in the p CO2 2 000 × 10 -6 and 10 000 × 10 -6 groups, and, in addition, the exposure time had noticeably impacts on these rates too. This study indicates that the reproductive performances of copepods were sensitive to elevated p CO2 , and that the response of different copepod species to acidified seawater was different. Furthermore, the synergistic effects of seawater acidification and climate change or other pollutant stresses on organisms should be given more attention.展开更多
The Paper is the succession of the study on abundance distribution of planktonic copepods in the waters north of Taiwan, and the emphasis is laid on the analysis and discussion of the constructions and features of cop...The Paper is the succession of the study on abundance distribution of planktonic copepods in the waters north of Taiwan, and the emphasis is laid on the analysis and discussion of the constructions and features of copepod community and the relationships with water environment. The results show as follows: a total of 237 species were identified and the construction of communtity was complex. The percentage of annual present species was only 32%. The mean values of diversity and homogeneity of the copepod community were 3. 714 and 0. 690 respectively, and their horizontal distribution patterns were higher in outshore area than in nearshore area. The copepods of the area could be divided into five ectotypes. Warm-water outshore high temperature and lower saline group and tropic oceanic high temperature and saline group could indicate the seasonal changes of the Taiwan Strait water and the Kuroshio surface water respectively. According to the various aspects of calculation and analysis, winter was different from other three seasons in environmental conditions. In spring, summer and autumn, Undinula valgaris was the meat dominant species and salinity was the main factor that affected the community feature values. The communities in the three seasons had the subtropic-tropic characteristics in which warm-water outshore species were dominant and tropic oceanic species accounted for also certain proportion. While in winter, the dominant species was Euchaeta manna and temperature was the main factor influencing the community feture values. The community had the tropic oceanic characteristics in which tropic oceanic species were dominant.展开更多
Abstract Selection of net with a suitable mesh size is a key concern in the quantitative assessment of zooplankton, which is cru- cial to understand pelagic ecosystem processes. This study compared the copepod collect...Abstract Selection of net with a suitable mesh size is a key concern in the quantitative assessment of zooplankton, which is cru- cial to understand pelagic ecosystem processes. This study compared the copepod collecting efficiency of three commonly used plankton nets, namely, the China standard coarse net （505 gm mesh）, the China standard fine net （77 gin）, and the WP-2 net （200 μm） The experiment was performed at six stations in the Bohai Sea during the autumn of 2012. The coarse net substantially un- der-sampled small individuals （body widths 〈 672 gm） and led to the lowest species number in each tow, whereas the fine net col- lected all small copepod species but failed to collect rare species. The WP-2 net appeared to be a compromise of the two other nets, collecting both small copepods and rare species. The abundance of copepods collected by the coarse net （126.4±86.5 indm-3） was one to two orders of magnitude lower than that by the WP-2 net （5802.4 ± 2595.4 indm3）, and the value of the fine net （11117.0±4563.41 indm-3） was nearly twice that of the WP-2 net. The abundance of large copepods （i.e., adult Calanus sinicus） in the three nets showed no significant differences, but the abundance of small copepods declined with decreasing mesh size. The dif- ference in abundance resulted from the under-sampling of small copepods with body widths 〈 672 μm and 〈 266μm by the coarse and WP-2 nets, respectively.展开更多
From 1997 to 2000, four field surveys were conducted in the East China Sea （ECS） （23°30＇-33°00＇N, 118°30＇-128°00＇E）. A field data yield density model was used to determine the optimal salin...From 1997 to 2000, four field surveys were conducted in the East China Sea （ECS） （23°30＇-33°00＇N, 118°30＇-128°00＇E）. A field data yield density model was used to determine the optimal salinities for 19 dominant copepod species to establish the relationship between surface salinities and abundance of those species. In addition, ecological groups of the copepods were classified based on optimal salinity and geographical distribution. The results indicate that the yield density model is suitable for determining the relationship between salinity and abundance. Cosmocalanus darwini, Euchaeta rimana, Pleuromamma gracilis, Rhincalanus cornutus, Scolecithrix danae and Pareucalanus attenuatus were determined as oceanic species, with optimal salinities of 〉34.0. They were stenohaline and mainly distributed in waters influenced by the Kuroshio or Taiwan warm current. Temora discaudata, T. stylifera and Canthocalanus pauper were nearshore species with optimal salinities of 〈33.0 and most abundant in coastal waters. The remaining 10 species, including Undinula vulgaris and Subeucalanus suberassus, were offshore species, with optimal salinity ranging from 33.0-34.0. They were widely distributed in nearshore, offshore and oceanic waters but mainly in the mixed water of the ECS.展开更多
UV radiation is known to affect aquatic primary producers and their grazers. However, little has been documented on its effects on zooplankton grazing. In this study, the authors investigated the effects of photosynth...UV radiation is known to affect aquatic primary producers and their grazers. However, little has been documented on its effects on zooplankton grazing. In this study, the authors investigated the effects of photosynthetically active radiation （PAR, 400–700 nm）, ultraviolet-A （UV-A, 320–400 nm） and ultraviolet-B （UV-B, 280–320 nm） radiation on grazing, mortality and lipids oxidation of the copepod Acartia pacifica collected from the Xiamen Bay. After 30 min of the exposures, the copepod was fed in darkness with the diatom Phaeodactylum tricornutum at two cell concentrations （2.5 × 10 4 and 2.5 × 10 5 cells/ml）. At the low cell concentration, the individuals pre-exposed to PAR （218.0 W/m 2 ）＋UV-A （48.2 W/m 2 ） or PAR＋UV-A＋UV-B （2.1 W/m 2 ） showed suppressed clearance and grazing activities compared with those receiving PAR alone, by 22.7% and 17.1% for clearance and by 22.6% and 5.5% for grazing rates, respectively. However, the suppression on clearance and grazing became indistinctive at the high food concentration. Exposures to UV-A and UV-B led to increased lipid oxidation and higher mortality, furthermore, the mortality linearly increased with enhanced oxidation of lipid.展开更多
Zooplankton constitutes a major part of the diet for fish larvae in the marine food web, and it is generally believed that copepods can meet the nutritional requirements of fish larvae. In this study, calanoid copepod...Zooplankton constitutes a major part of the diet for fish larvae in the marine food web, and it is generally believed that copepods can meet the nutritional requirements of fish larvae. In this study, calanoid copepod Schmackeria poplesia, rotifer Brachionus plicatilis and anostraca crustacean Artemia sp. were analyzed for fatty acid contents, and were used as live food for cul- turing larval Japanese flounder, Paralichthys olivaceus. The total content of three types of HUFAs （DHA, EPA and ARA） in S. po- plesia was significantly higher than that in the other two live foods （P〈O.O1）. Three live organisms were used for raising larvae and juveniles of Paralichthys olivaceus respectively for 15 and 10 d. Then the growth, survival and fatty acid composition of the larvae and juveniles were investigated. The results showed that the larvae and juveniles fed with copepods （S. poplesia） had significantly higher growth rate than those fed with the other two organisms （P〈0.01）. The survival of the flounder larvae fed with copepods was significantly higher than that of the others （P〈0.01）, and the survival of the juvenile fish fed with copepods was higher than that fed with Artemia （P〈0.05）. The contents of three types of HUFAs （DHA, EPA and ARA） and the ratio of DHA/EPA in larval and juve- nile flounder P. olivaceus were analyzed. The results showed that the contents of DHA, EPA and ARA in the larvae and juveniles fed with S. poplesia were higher than those fed with a mixed diet orArtemia only, and the ratio of EPA/ARA in larvae and juveniles of P. olivaceus fed with S. poplesia was lower than that in the case of feeding with a mixed diet or Artemia only. The present data showed that copepod is the best choice for feeding the larvae and juveniles of fish considering its effects on the survival, growth and nutrition composition of the fish.展开更多
This study aims to investigate the seasonal variations in copepod community structure and prosome length of dominant species from March 2009 to January 2010 around artificial reefs in Xiaoshi Island, Yellow Sea, Weiha...This study aims to investigate the seasonal variations in copepod community structure and prosome length of dominant species from March 2009 to January 2010 around artificial reefs in Xiaoshi Island, Yellow Sea, Weihai, China. Samples were collected using two types of plankton net （Model I and Model II） for different-sized copepods. The number of taxon was calculated from the data of both the net types, while the copepod abundance was done using the samples from Model II only. Sixteen species of planktonic copepods, including 5 dominant species, were recorded. Results reveal that Oithona similis was the first dominant species from March to June, and was replaced by Paracalanus parvus in September; both dominated the copepod community in January. Acartia hongi was the second dominant species from March to September. Centropages abdominalis was the third dominant species from March to June, and was replaced by O. sirnilis in September and Corycaeus aJfinis in January. C. affinis was the fourth dominant species in September. Population density of the dominant copepods was compared with that of other similar regions. We found that the dominant species were mostly small copepods （〈1 mm） except for adult Centrapages abdominalis. Seasonal variation in prosome length of O. similis, C. abdominalis, and C. affinis, and their copepodites were studied for the first time in China. For P. parvus and A. hongi, seasonal trends in prosome length variation were similar with those in Jiaozhou Bay, Yellow Sea, Qingdao, China, in a similar temperate domain. The results are helpful for future calculation of copepod biomass and production, and for investigation of the relationship between copepods and fish resources.展开更多
Brown tides have recurred in estuary areas globally,but trophic interactions between the causative species Aureococcus anophagefferens and planktonic copepods remain poorly understood.In this study,we investigated per...Brown tides have recurred in estuary areas globally,but trophic interactions between the causative species Aureococcus anophagefferens and planktonic copepods remain poorly understood.In this study,we investigated performance（ingestion,growth,development and reproduction） of the planktonic copepod,Pseudodiaptomus poplesia,offered either mono-algal or mixed-algal diets containing a Chinese strain of A.anophagefferens.A typical Michaelis-Menten pattern existed between ingestion rate and food level when copepod fed on the monoalgal diet of this species.Nauplii exhibited the highest maximum ingestion rate（Imax） than copepodids and adult females.In addition,Imax value was higher in nauplii feeding on A.anophagefferens than on Skeletonema costatum.When fed mixtures of A.anophagefferens and S.costatum,P.poplesia selected against A.anophagefferens cells,but less strongly at the naupliar stage.Nauplii did not undergo metamorphosis and died at late naupliar stages feeding on A.anophagefferens alone,similar to those under starvation.Furthermore,the presence of A.anophagefferens greatly reduced the reproduction rate of females in mixtures but did not influence the growth rate of copepodids.These results suggest that P.poplesia nauplii may exert grazing pressure on A.anophagefferens population during a brown tide,which,however,may not be persistent because of copepod population decline.展开更多
The potential suppression of copepods on appendicularians was found in field and experimental conditions. The abundance and distribution of appendicularians and planktonic copepods were studied with reference to their...The potential suppression of copepods on appendicularians was found in field and experimental conditions. The abundance and distribution of appendicularians and planktonic copepods were studied with reference to their correlations during summer on the northwest continental shelf of the South China Sea （SCS）. Based on the topography and water mass of the surveyed region, it was divided into three sub-regions： Region I （inshore waters of the east Leizhou Peninsula） with low temperature, salinity and high chlorophyll a （Chl a） concentration, Region II （inshore waters of the east and southeast Hainan Island） with low temperature, high salinity and moderate Chl a concentration and Region III （offshore waters from the Leizhou Peninsula to Hainan Island） with high temperature, high salinity and low Chl a concentration. The species richness of appendicularians and copepods increased from the inshore to offshore waters, and high values were observed in Region III. The distribution of appendicularian and copepod abundance decreased generally from the inshore to offshore waters, with the highest values at Region I. Our results suggest that the distribution patterns of appendicularians and copepods differed significantly, as a result of the influence of physical and biological factors. The negative impact of pelagic copepods on appendicularians was not found based on in situ data in the northwest continental shelf of SCS.展开更多
Copepods are a key trophic link between primary producers and predatory animals at higher trophic levels in the marine ecosystem. Knowledge of the in situ composition of the copepod diet is critical for the accurate e...Copepods are a key trophic link between primary producers and predatory animals at higher trophic levels in the marine ecosystem. Knowledge of the in situ composition of the copepod diet is critical for the accurate evaluation of trophic relationships and energy transfer in marine food webs. In this study, we applied a PCR-based cloning technique developed previously to investigate the in situ diet of Calanus sinicus, an ecologically important largesized calanoid copepod that dominates in the shelf waters around China, Japan and Korea. Analyses of the 18S rDNA sequences obtained from the copepod diet revealed the diverse food composition of C. sinicus from two stations （Y19 in the South Yellow Sea and B49 in the Bohai Sea）. A total of 43 operational taxonomic units （OTUs） were detected, which belonged to 13 diverse lineages： Bacillariophyta, Dinoflagellata, Dictyochophyceae, Chrysophyta, Katablepharidophyta, Pelagophyceae, Apusozoa, Hydrozoa, Ctenophora, Echinodermata, Tunicata, Chaetognatha and marine fungi. The results indicate that during an algae bloom, C. sinicus can graze on the bloom causative species. When the abundance of phytoplankton in ambient water is relatively low, C. sinicus can choose eggs, larvae, or organic particles/detritus of various metazoans, especially hydrozoans and ctenophores, as alternative food sources. Our result suggests that C. sinicus is an omnivorous species, and its prey choice may depend on the food availability in the ambient waters.展开更多
The horizontal and vertical distribution patterns of five planktonic copepods, Calanus sinicus, Acartia pacifica, Tortanus derjugini, Acartiella sinensis and Pseudodiaptomus poplesia, predominant in the Jiulong Estuar...The horizontal and vertical distribution patterns of five planktonic copepods, Calanus sinicus, Acartia pacifica, Tortanus derjugini, Acartiella sinensis and Pseudodiaptomus poplesia, predominant in the Jiulong Estuary, were investigated from May 2003 to April 2004. The results showed that the distribution of these copepods was related to the tidal period but that each species had its own specific pattern. C. sinicus showed no tidal vertical migration behavior and was thought to be a non-resident species in this estuary. Among Acartia pacifica, T. derjugini,Acartiella sinensis, more individuals occurred in the surface than in the bottom waters during flood tide, and the pattern was reversed during ebb tide. The epibenthic copepod P. poplesia usually remained in the bottom waters in the upstream part of the estuary, but it displayed strong tidally-oriented vertical migration in the middle reaches of the estuary. Taking into account the hydrographic characteristics of the Jiulong Estuary, it was hypothesized that the planktonic copepods in this estuary had more or less adopted the mechanism of vertically migrating to the surface waters during flood tide in order to make use of the inflowing tide, and then sinking to the bottom during ebb tide to avoid being carried out of the estuary by net outflow.展开更多
To understand the effects of the Yellow Sea Cold Bottom Water （YSCBW） on the diel vertical migration （D- VM） of the copepod Calanus sinicus, we surveyed vertical distribution of C. sinicus at a fixed station in th...To understand the effects of the Yellow Sea Cold Bottom Water （YSCBW） on the diel vertical migration （D- VM） of the copepod Calanus sinicus, we surveyed vertical distribution of C. sinicus at a fixed station in the Yellow Sea before （spring） and during （summer） formation of the YSCBW. Cold water （〈10℃） was observed in the bottom layer when the water column was thermally stratified in summer, but the water column was thermally well-mixed in spring 2010. Samples were collected from five different layers at 3-h intervals using an opening-closing net. Adult females （1-155 ind./m3） showed a clear normal DVM pattern throughout the entire water column in spring, whereas adult males did not migrate. DVM of copepodite V （CV） individuals was not clear, but the maximum abundance of CI-CIV occurred consistently in the upper 10-20 m layer, where there was a high concentration of chlorophyll-a （Chl-a） （0.49-1.19μg/L）. In summer, weak DVM was limited to cold waters beneath the thermocline for adult females （〈30 ind./m3）, but not for adult males. The maximum abundance of CI-CIV also occurred consistently in the subsurface layer （20-40 m） together with high concentrations of Chl-a （0.81-2.36 μg/L）. CV individuals （1-272 ind./m3） moved slightly upward noc- turnally to the near-surface layer （10-20 m）, where the average temperature was 25.74℃, but they were not found in the surface layer （0-10 m; 28.31℃）. These results indicate that the existence of the YSBCW affected food availability at depth and the vertical temperature distribution, leading to variation in the amplitude and shape of stage-specific vertical distributions （CI to adults） in C. sinicus before and during the formation of cold waters in the Yellow Sea during the study period.展开更多
The sensitivity of freshwater invertebrates to agricultural pollutants is supposed to increase with rising temperature due to global warming. The aim of this study was to measure the effect of temperature on the letha...The sensitivity of freshwater invertebrates to agricultural pollutants is supposed to increase with rising temperature due to global warming. The aim of this study was to measure the effect of temperature on the lethal toxicity of ammonia-N, the herbicide Imazamox and the mixture of the two chemicals, in the adults and the juveniles of a population of the copepod Eucyc- lops serrulatus. This is a widely distributed species found in surface waters, in transitional habitats between surface water and groundwater, and in genuine groundwater environments. We tested the sensitivity by short-term bioassays （96 h） at 15℃ and 18℃, respectively. Our results highlighted the following： （1） increasing temperature affected the sensitivity of the adults to am- monia-N and of the juveniles to the mixture, all of which were more sensitive to its detrimental effects at 18~C; （2） the juvenile stages were more sensitive than the adults to all toxicants, and （3） for all combinations of chemicals and temperatures, the effects were synergistic and approximately one order of magnitude greater than those expected according to a concentration addition model when comparing the LC50 for each chemical in the mixture with the LC50s of chemicals individually assayed. Overall, in a context of global change, ammonia-N and mixtures of agricultural pollutants may affect the survival rate of species that spend a part or the whole life-cycle in the hyporheic habitat, with detrimental effects to biodiversity and ecosystem services provided by the hyporheic biota [Current Zoology 61 （4）： 629~540, 2015].展开更多
基金the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.LSKJ202203206)the Fundamental Research Funds for the Central Universities(No.202161069)。
文摘Blooms of the toxic dinoflagellate Alexandrium spp.,which produce paralytic shellfish toxins(PSTs),have threatened marine ecosystems for decades.However,their impacts on benthic copepods remain underexplored.Here,we investigated the physiological and biochemical responses of marine benthic copepod Tigriopus japonicus to Alexandrium pacificum.Adult female showed no mortality within 24 h and maintained high survival(>80%)across all A.pacificum concentrations over 96 h,with no significant difference from non-toxic controls.Ingestion rates on A.pacificum and non-toxic controls were similar,when algal prey concentrations were lower than about 2500µgC/L.However,above this threshold,feeding of T.japonicus was significantly depressed by A.pacificum.Six-day exposure induced oxidative stress,marked by elevated level of reactive oxygen species,malondialdehyde,total antioxidant capacity and superoxide dismutase activity,while catalase activity showed a non-significant increase.Moreover,concentration-dependent increase was observed in acetylcholinesterase activity,and its positive correlation with oxidative biomarkers suggests additional roles in coping with stress.Chronic exposure over three generations did not consistently affect development,except for complete development failure in F2 and F3 at the highest concentration.However,moderate-to-high concentrations of A.pacificum significantly impaired reproduction,reducing egg production by 9.66%–96.07%and clutch numbers by 33.33%–55.56%.Our findings indicate that Alexandrium blooms can adversely impact benthic copepod feeding and population recruitment through neurotoxicity and oxidative stress,highlighting the ecological risks of prolonged algal blooms in benthic habitats.
基金the Port and Fisheries Division of the PWD and IWT Department, Government of Karnataka,for providing the research grant for executing the project(SSP 3243)
文摘The spatial variability of mesozooplankton(MZ)community characteristics,with an emphasis on the predominant taxa,copepods,were evaluated between two distinct coastal water environments of Mangalore:the Netravati-Gurupura estuarine system(NGES)and the adjacent nearshore waters(<20 m depth)on the southwest coast of India during winter 2018.The nearshore waters were characterised by uniformly distributed hydrographic properties,particularly in terms of water column temperature,salinity and turbidity.This well-mixed water column likely stimulated increased phytoplankton chlorophyll a concentrations[av.(2.9±2.2)mg/m^(3)],which in turn supported higher MZ biomass[av.(0.4±0.15)mL/m^(3)]and abundance[av.(6889±3387)ind./m^(3)]in the nearshore waters.In contrast,the NGES exhibited highly variable hydrographic conditions,leading to inconsistent chlorophyll a[av.(3.2±3.7)mg/m^(3)],along with significantly lower MZ biomass[av.(0.1±0.2)mL/m^(3)]and abundance[av.(238±339)ind./m^(3)].The MZ community was dominated by herbivorous copepods(HCs),particularly Bestiolina similis,in the entire study region;however,the nearshore waters supported a more diverse taxon.The overall dominance of HCs,e.g.,B.similis and Pseudodiaptomous aurivillii,in the nearshore waters,indicates the presence of stable hydrographic conditions,especially consistently higher salinity and chlorophyll a level.In contrast,the unstable hydrographic conditions in the NGES,primarily reflected in the uneven salinity distributions,likely contributed to the reduced MZ biomass and abundance.The relative increase in the abundance of B.similis observed exclusively in the euhaline zones of the estuary highlights the significant influence of neritic waters.
基金Supported by the National Natural Science Foundation of China(Nos.U 23 A 2048,42376152,42076148)the Special Program of Key Sectors in Guangdong Universities(Nos.2022 ZDZX 4040,2023 KCXTD 028)。
文摘Silicon limitation negatively affects the growth and metabolism of diatoms.However,its influence on the topography and mechanical properties of diatom frustules,and consequently on predation,remains unclear.We investigated how silicon limitation affects the mechanical strength of diatom frustules.Under silicon limitation,the growth rates of diatom Cylindrotheca closterium,Amphora coffeaeformis,Thalassiosira weissflogii,and Cyclotella sp.decreased by 19%,56%,42%,and 73%,respectively.Similarly,the biogenic silica content of silicon-limited C.closterium,T.weissflogii,and Cyclotella sp.decreased by 17%,11%,and 9%,respectively,whereas A.coffeaeformis showed a 63%increase.Atomic force microscopy and X-ray photoelectron spectroscopy revealed that silicon shortage reduced frustule hardness by approximately 60%and decreased condensed silica components on their surface by about 80%,except in A.coffeaeformis.Additionally,copepods consumed 20%to 600%more diatoms grown under silicon deficiency compared to those grown under Si-rich conditions,with the exception of A.coffeaeformis.These findings suggest that silicon limitation diminishes diatom populations and accelerates carbon export from diatoms to the deep sea.
基金The National Natural Science Foundation of China Project under contract No.42206150the Technology Development Program of Shanghai Ocean University under contract No.A2-2006-20-200207.
文摘In the paper,copepod universal formulas are applied to construct a copepod individual-based model(IBM),and a genetic algorithm(GA)is incorporated in the formulas with genes as species parameters.The IBM initially constructs the individuals with all possible genes similar to the original state of natural selection.Climate-averaged temperature and chlorophyll a(Chl a)time series at the surface layer of fixed points in the Georges Bank(GB)and the Gulf of Maine(GOM)are taken as the model environment.The IBM has been running for 50 a in the environment without inter-annual change.The IBM results indicate that some of the life history traits of the top ten abundant species output by the IBM in the GB and the GOM are consistent with the real species Calanus finmarchicus,Pseudocalanus spp.,Centropages typicus,and Centropages hamatus in terms of reproduction strategy,time to reach the maximum abundance,water temperature preference,and adult body mass.The study of the top ten abundant species with multidimensional scaling(MDS)and clustering analysis(CA)methods indicates that reproduction strategy is the basis for grouping.For the species taking the broadcasting strategy,both GB and GOM environments tend to choose smallbodied species with cold-water preference,such as Pseudocalanus spp.;for the species taking the egg-carrying strategies,the GB environment selects large-bodied species with cold-water preference,such as C.finmarchicus,while the GOM environment selects medium-bodied species with warm-water preference,such as Centropages spp.(C.typicus and C.hamatus).After gene mutation is added to the IBM,the model result gets simple,which needs to be further improved.The significance of the paper lies in systematically studying the impact of GB and GOM environments on the evolutionary life history traits of copepods for the first time.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX2-YW-213-3)the National Basic Research Program of China (973 Program) (No. 2006CB400606)the National Natural Science Foundation of China (No. 40631008)
文摘Differences among species in prosome length and in species' response to environmental factors do exist. Therefore, it is useful to examine prosome length for different copepod species in variable environments. Seasonal variations in prosome length of four small copepods and their copepodite stages in the Jiaozhou Bay were compared and the relative influence of temperature, salinity, and chlorophyll concentration were examined. Two peaks were found in the mean prosome length of Paracalanus parvus (in early winter and May). For Acartia bifilosa, the maximum values of all copepodites occurred mainly from February to April, and decreased to the bottom in July. Prosome length of Acartia pacifica peaked when it first appeared in June, then reached to the minimum in July. Parvocalanus crassirostris only appeared from late summer to autumn and the mean prosome length showed no clear changes. Correlations of adult prosome length with environmental factors were evaluated. For the four species, temperature was negatively correlated to prosome length except for P. crassirostris. But the different species varied markedly in their responds to temperature. A. bifilosa showed a more definite trend of size variation with temperature than P. parvus and A. pacifica. Correlations of prosome length with salinity were significantly positive for almost all the small copepods. The relationship between chlorophyll concentration and prosome length was complicated for these copepods, but for P. parvus, chlorophyll concentration was also an important affecting factor. Furthermore, investigation needs to be done on food quality for some copepod. These results are essential to estimate the biomass and the production, and to understand these small copepods' population dynamics in this human-affected bay.
基金The National Natural Science Foundation of China under contract Nos 40876066 and 41076085the National Basic Research Program of China under contract No.2005CB422306
文摘Planktonic copepod Calanus sinicus is the dominant meso-zooplankton in the Northwest Pacific Ocean. To better understand its population dynamics and phylogeographic patterns, 243 C. sinicus individuals were collected from seven locations across the shelf waters of China and its population genetics was studied by mitochondrial DNA cytochrome oxidase I（mtCOI） sequences analyses. Thirty-nine different sequences, or haplotypes, were detected with moderate haplotype diversity（h=0.749） and low nucleotide diversity（π=0.003） for all populations. The evolutionary divergence between geographic populations varied from 0.24% to 0.37%, indicative of very limited genetic differentiation. Visualized minimum spanning network（MSN） and phylogenetic analysis of all the detected haplotypes did not reveal any clear phylogeographic pattern. Furthermore, AMOVA data showed no significant spatial population differentiation existed among the individuals collected across China shelf waters. Pairwise FST values showed that population collected from northwest of the East China Sea（ECS） displayed a low difference to other populations. Mismatch distribution analyses and neutrality tests indicated that C. sinicus might undergo a demographic/population expansion. No significant population genetic structuring was detected, indicating an extensive gene flow among the C. sinicus populations. Our results provide molecular evidence for the hypothesis that C. sinicus in the northwestern South China Sea in winter is transported from the East China Sea and the Yellow Sea by the China Coastal Current during the northeast monsoon period.
文摘Paracalanus parvus, Paracalanus crassirostris , and Acartia bifilosa are dominant and widely distributed in the Bohai Sea, and comprise an important part of zooplankton in terms of biomass as well as production rate. In order to understand their seasonal distribution and population dynamics, their stage specific abundance in different months of the year were analyzed based on the never analyzed yet samples collected in 1959. The three species showed clear and remarkable seasonal variation in abundance, which maximized in spring and summer, when they formed high biomass patches or concentrations in the nearshore area. For Paracalanus parvus , two peaks were observed in the annual circle, one in June and the other in September. For Paracalanus crassirostris , one peak occurred in summer and a small one in December. The seasonal pattern of Acartia bifilosa was different in different regions. In Bohai Bay it had a two peak pattern, with the first large peak occurring in May and the second one in October. In Laizhou Bay, a winter peak in December and January could be observed besides the spring one. The number of generations during the reproductive season for the three species was estimated based on the annual cycle in abundance and ambient temperature.
基金The State Oceanic Administration Foundation of China under contract No.200805029
文摘Ecological experiments were conducted to examine the effects of seawater containing elevated par- tial pressure of carbon dioxide （p CO2 800 × 10 -6 , 2 000 × 10 -6 , 5 000 × 10 -6 and 10 000 × 10 -6 ） on the survival and reproduction of female Acartia pacifica, Acartia spinicauda, Calanus sinicus and Centropages tenuiremis, which are the dominant copepods in the southern coastal waters of China. The results show that the effects of elevated p CO2 on the survival rates of copepods were species-specific. C. sinicus, which was a macro-copepod, had a higher survival rate （62.01%–71.96%） than the other three species （5.00%–26.67%） during the eight day exposure. The egg production rates of C. sinicus, A. spinicauda and C. tenuiremis were significantly inhibited by the increased p CO2 and the exposure time duration. There were significantly negative impacts on the egg hatching success of A. spinicauda and C. tenuiremis in the p CO2 2 000 × 10 -6 and 10 000 × 10 -6 groups, and, in addition, the exposure time had noticeably impacts on these rates too. This study indicates that the reproductive performances of copepods were sensitive to elevated p CO2 , and that the response of different copepod species to acidified seawater was different. Furthermore, the synergistic effects of seawater acidification and climate change or other pollutant stresses on organisms should be given more attention.
基金The work was supported by the National Natural Science Foundation of China under contract !No. 49576275.
文摘The Paper is the succession of the study on abundance distribution of planktonic copepods in the waters north of Taiwan, and the emphasis is laid on the analysis and discussion of the constructions and features of copepod community and the relationships with water environment. The results show as follows: a total of 237 species were identified and the construction of communtity was complex. The percentage of annual present species was only 32%. The mean values of diversity and homogeneity of the copepod community were 3. 714 and 0. 690 respectively, and their horizontal distribution patterns were higher in outshore area than in nearshore area. The copepods of the area could be divided into five ectotypes. Warm-water outshore high temperature and lower saline group and tropic oceanic high temperature and saline group could indicate the seasonal changes of the Taiwan Strait water and the Kuroshio surface water respectively. According to the various aspects of calculation and analysis, winter was different from other three seasons in environmental conditions. In spring, summer and autumn, Undinula valgaris was the meat dominant species and salinity was the main factor that affected the community feature values. The communities in the three seasons had the subtropic-tropic characteristics in which warm-water outshore species were dominant and tropic oceanic species accounted for also certain proportion. While in winter, the dominant species was Euchaeta manna and temperature was the main factor influencing the community feture values. The community had the tropic oceanic characteristics in which tropic oceanic species were dominant.
基金funded by the Fundamental Research Funds for the Central Universities (No.201262017)the National Natural Science Foundation of China (No.41210008)
文摘Abstract Selection of net with a suitable mesh size is a key concern in the quantitative assessment of zooplankton, which is cru- cial to understand pelagic ecosystem processes. This study compared the copepod collecting efficiency of three commonly used plankton nets, namely, the China standard coarse net （505 gm mesh）, the China standard fine net （77 gin）, and the WP-2 net （200 μm） The experiment was performed at six stations in the Bohai Sea during the autumn of 2012. The coarse net substantially un- der-sampled small individuals （body widths 〈 672 gm） and led to the lowest species number in each tow, whereas the fine net col- lected all small copepod species but failed to collect rare species. The WP-2 net appeared to be a compromise of the two other nets, collecting both small copepods and rare species. The abundance of copepods collected by the coarse net （126.4±86.5 indm-3） was one to two orders of magnitude lower than that by the WP-2 net （5802.4 ± 2595.4 indm3）, and the value of the fine net （11117.0±4563.41 indm-3） was nearly twice that of the WP-2 net. The abundance of large copepods （i.e., adult Calanus sinicus） in the three nets showed no significant differences, but the abundance of small copepods declined with decreasing mesh size. The dif- ference in abundance resulted from the under-sampling of small copepods with body widths 〈 672 μm and 〈 266μm by the coarse and WP-2 nets, respectively.
基金Supported by the National Natural Science Foundation of China (Nos. 40776047, 90511005)the National Basic Research Program of China (973 Project) (No. 2010CB428705)
文摘From 1997 to 2000, four field surveys were conducted in the East China Sea （ECS） （23°30＇-33°00＇N, 118°30＇-128°00＇E）. A field data yield density model was used to determine the optimal salinities for 19 dominant copepod species to establish the relationship between surface salinities and abundance of those species. In addition, ecological groups of the copepods were classified based on optimal salinity and geographical distribution. The results indicate that the yield density model is suitable for determining the relationship between salinity and abundance. Cosmocalanus darwini, Euchaeta rimana, Pleuromamma gracilis, Rhincalanus cornutus, Scolecithrix danae and Pareucalanus attenuatus were determined as oceanic species, with optimal salinities of 〉34.0. They were stenohaline and mainly distributed in waters influenced by the Kuroshio or Taiwan warm current. Temora discaudata, T. stylifera and Canthocalanus pauper were nearshore species with optimal salinities of 〈33.0 and most abundant in coastal waters. The remaining 10 species, including Undinula vulgaris and Subeucalanus suberassus, were offshore species, with optimal salinity ranging from 33.0-34.0. They were widely distributed in nearshore, offshore and oceanic waters but mainly in the mixed water of the ECS.
基金The Changjiang Scholars and Innovative Research Team Program under contract No. IRT0941Shanghai Municipal Natural Science Foundation under contract No. 11ZR1449900Visiting Scholarship of State Key Laboratory of Marine Environmental Science, Xiamen University under contract No. MELRS0919
文摘UV radiation is known to affect aquatic primary producers and their grazers. However, little has been documented on its effects on zooplankton grazing. In this study, the authors investigated the effects of photosynthetically active radiation （PAR, 400–700 nm）, ultraviolet-A （UV-A, 320–400 nm） and ultraviolet-B （UV-B, 280–320 nm） radiation on grazing, mortality and lipids oxidation of the copepod Acartia pacifica collected from the Xiamen Bay. After 30 min of the exposures, the copepod was fed in darkness with the diatom Phaeodactylum tricornutum at two cell concentrations （2.5 × 10 4 and 2.5 × 10 5 cells/ml）. At the low cell concentration, the individuals pre-exposed to PAR （218.0 W/m 2 ）＋UV-A （48.2 W/m 2 ） or PAR＋UV-A＋UV-B （2.1 W/m 2 ） showed suppressed clearance and grazing activities compared with those receiving PAR alone, by 22.7% and 17.1% for clearance and by 22.6% and 5.5% for grazing rates, respectively. However, the suppression on clearance and grazing became indistinctive at the high food concentration. Exposures to UV-A and UV-B led to increased lipid oxidation and higher mortality, furthermore, the mortality linearly increased with enhanced oxidation of lipid.
基金supported by the National High-Tech Research and Development Program of China (863 Program, Nos. 2002AA629100 and 2004AA626100
文摘Zooplankton constitutes a major part of the diet for fish larvae in the marine food web, and it is generally believed that copepods can meet the nutritional requirements of fish larvae. In this study, calanoid copepod Schmackeria poplesia, rotifer Brachionus plicatilis and anostraca crustacean Artemia sp. were analyzed for fatty acid contents, and were used as live food for cul- turing larval Japanese flounder, Paralichthys olivaceus. The total content of three types of HUFAs （DHA, EPA and ARA） in S. po- plesia was significantly higher than that in the other two live foods （P〈O.O1）. Three live organisms were used for raising larvae and juveniles of Paralichthys olivaceus respectively for 15 and 10 d. Then the growth, survival and fatty acid composition of the larvae and juveniles were investigated. The results showed that the larvae and juveniles fed with copepods （S. poplesia） had significantly higher growth rate than those fed with the other two organisms （P〈0.01）. The survival of the flounder larvae fed with copepods was significantly higher than that of the others （P〈0.01）, and the survival of the juvenile fish fed with copepods was higher than that fed with Artemia （P〈0.05）. The contents of three types of HUFAs （DHA, EPA and ARA） and the ratio of DHA/EPA in larval and juve- nile flounder P. olivaceus were analyzed. The results showed that the contents of DHA, EPA and ARA in the larvae and juveniles fed with S. poplesia were higher than those fed with a mixed diet orArtemia only, and the ratio of EPA/ARA in larvae and juveniles of P. olivaceus fed with S. poplesia was lower than that in the case of feeding with a mixed diet or Artemia only. The present data showed that copepod is the best choice for feeding the larvae and juveniles of fish considering its effects on the survival, growth and nutrition composition of the fish.
基金Supported by the National Natural Science Foundation of China(No.41106133)the Shandong University Independent Innovation Foundation(No.2011ZRYQ005)the Program of Academy of Marine Research in Weihai(No.000041342080)
文摘This study aims to investigate the seasonal variations in copepod community structure and prosome length of dominant species from March 2009 to January 2010 around artificial reefs in Xiaoshi Island, Yellow Sea, Weihai, China. Samples were collected using two types of plankton net （Model I and Model II） for different-sized copepods. The number of taxon was calculated from the data of both the net types, while the copepod abundance was done using the samples from Model II only. Sixteen species of planktonic copepods, including 5 dominant species, were recorded. Results reveal that Oithona similis was the first dominant species from March to June, and was replaced by Paracalanus parvus in September; both dominated the copepod community in January. Acartia hongi was the second dominant species from March to September. Centropages abdominalis was the third dominant species from March to June, and was replaced by O. sirnilis in September and Corycaeus aJfinis in January. C. affinis was the fourth dominant species in September. Population density of the dominant copepods was compared with that of other similar regions. We found that the dominant species were mostly small copepods （〈1 mm） except for adult Centrapages abdominalis. Seasonal variation in prosome length of O. similis, C. abdominalis, and C. affinis, and their copepodites were studied for the first time in China. For P. parvus and A. hongi, seasonal trends in prosome length variation were similar with those in Jiaozhou Bay, Yellow Sea, Qingdao, China, in a similar temperate domain. The results are helpful for future calculation of copepod biomass and production, and for investigation of the relationship between copepods and fish resources.
基金The National Natural Science Foundation of China under contract No.41276153the Joint Project of National Nature Science Foundation of China-Guangdong under contract No.U1301235+1 种基金the Public Science and Technology Research Funds Projects of Ocean under contract Nos 201305003-2 and 201305010-4the Fundamental Research Funds for the Central Universities
文摘Brown tides have recurred in estuary areas globally,but trophic interactions between the causative species Aureococcus anophagefferens and planktonic copepods remain poorly understood.In this study,we investigated performance（ingestion,growth,development and reproduction） of the planktonic copepod,Pseudodiaptomus poplesia,offered either mono-algal or mixed-algal diets containing a Chinese strain of A.anophagefferens.A typical Michaelis-Menten pattern existed between ingestion rate and food level when copepod fed on the monoalgal diet of this species.Nauplii exhibited the highest maximum ingestion rate（Imax） than copepodids and adult females.In addition,Imax value was higher in nauplii feeding on A.anophagefferens than on Skeletonema costatum.When fed mixtures of A.anophagefferens and S.costatum,P.poplesia selected against A.anophagefferens cells,but less strongly at the naupliar stage.Nauplii did not undergo metamorphosis and died at late naupliar stages feeding on A.anophagefferens alone,similar to those under starvation.Furthermore,the presence of A.anophagefferens greatly reduced the reproduction rate of females in mixtures but did not influence the growth rate of copepodids.These results suggest that P.poplesia nauplii may exert grazing pressure on A.anophagefferens population during a brown tide,which,however,may not be persistent because of copepod population decline.
基金Key Innovation Project of Chinese Academy of Sciences under contract No. KZCX2-YW-Q07the National Natural Science Foundation of China under contract Nos 31101619, 41276159 and 41130855Chinese Offshore Investigation and Assessment under contract No. 908-01-ST08
文摘The potential suppression of copepods on appendicularians was found in field and experimental conditions. The abundance and distribution of appendicularians and planktonic copepods were studied with reference to their correlations during summer on the northwest continental shelf of the South China Sea （SCS）. Based on the topography and water mass of the surveyed region, it was divided into three sub-regions： Region I （inshore waters of the east Leizhou Peninsula） with low temperature, salinity and high chlorophyll a （Chl a） concentration, Region II （inshore waters of the east and southeast Hainan Island） with low temperature, high salinity and moderate Chl a concentration and Region III （offshore waters from the Leizhou Peninsula to Hainan Island） with high temperature, high salinity and low Chl a concentration. The species richness of appendicularians and copepods increased from the inshore to offshore waters, and high values were observed in Region III. The distribution of appendicularian and copepod abundance decreased generally from the inshore to offshore waters, with the highest values at Region I. Our results suggest that the distribution patterns of appendicularians and copepods differed significantly, as a result of the influence of physical and biological factors. The negative impact of pelagic copepods on appendicularians was not found based on in situ data in the northwest continental shelf of SCS.
基金The National Natural Science Foundation of China under contract Nos 31372509,41076085 and 41328009
文摘Copepods are a key trophic link between primary producers and predatory animals at higher trophic levels in the marine ecosystem. Knowledge of the in situ composition of the copepod diet is critical for the accurate evaluation of trophic relationships and energy transfer in marine food webs. In this study, we applied a PCR-based cloning technique developed previously to investigate the in situ diet of Calanus sinicus, an ecologically important largesized calanoid copepod that dominates in the shelf waters around China, Japan and Korea. Analyses of the 18S rDNA sequences obtained from the copepod diet revealed the diverse food composition of C. sinicus from two stations （Y19 in the South Yellow Sea and B49 in the Bohai Sea）. A total of 43 operational taxonomic units （OTUs） were detected, which belonged to 13 diverse lineages： Bacillariophyta, Dinoflagellata, Dictyochophyceae, Chrysophyta, Katablepharidophyta, Pelagophyceae, Apusozoa, Hydrozoa, Ctenophora, Echinodermata, Tunicata, Chaetognatha and marine fungi. The results indicate that during an algae bloom, C. sinicus can graze on the bloom causative species. When the abundance of phytoplankton in ambient water is relatively low, C. sinicus can choose eggs, larvae, or organic particles/detritus of various metazoans, especially hydrozoans and ctenophores, as alternative food sources. Our result suggests that C. sinicus is an omnivorous species, and its prey choice may depend on the food availability in the ambient waters.
基金the National Natural Science Foundation of China under contract No. 40576065.
文摘The horizontal and vertical distribution patterns of five planktonic copepods, Calanus sinicus, Acartia pacifica, Tortanus derjugini, Acartiella sinensis and Pseudodiaptomus poplesia, predominant in the Jiulong Estuary, were investigated from May 2003 to April 2004. The results showed that the distribution of these copepods was related to the tidal period but that each species had its own specific pattern. C. sinicus showed no tidal vertical migration behavior and was thought to be a non-resident species in this estuary. Among Acartia pacifica, T. derjugini,Acartiella sinensis, more individuals occurred in the surface than in the bottom waters during flood tide, and the pattern was reversed during ebb tide. The epibenthic copepod P. poplesia usually remained in the bottom waters in the upstream part of the estuary, but it displayed strong tidally-oriented vertical migration in the middle reaches of the estuary. Taking into account the hydrographic characteristics of the Jiulong Estuary, it was hypothesized that the planktonic copepods in this estuary had more or less adopted the mechanism of vertically migrating to the surface waters during flood tide in order to make use of the inflowing tide, and then sinking to the bottom during ebb tide to avoid being carried out of the estuary by net outflow.
基金The study on the impact of the Yellow Sea Bottom Cold Water Mass to the ecosystem(YES Coldwater:PE99165)part of the Korea-China cooperative project on the Yellow Sea Cold Water Mass
文摘To understand the effects of the Yellow Sea Cold Bottom Water （YSCBW） on the diel vertical migration （D- VM） of the copepod Calanus sinicus, we surveyed vertical distribution of C. sinicus at a fixed station in the Yellow Sea before （spring） and during （summer） formation of the YSCBW. Cold water （〈10℃） was observed in the bottom layer when the water column was thermally stratified in summer, but the water column was thermally well-mixed in spring 2010. Samples were collected from five different layers at 3-h intervals using an opening-closing net. Adult females （1-155 ind./m3） showed a clear normal DVM pattern throughout the entire water column in spring, whereas adult males did not migrate. DVM of copepodite V （CV） individuals was not clear, but the maximum abundance of CI-CIV occurred consistently in the upper 10-20 m layer, where there was a high concentration of chlorophyll-a （Chl-a） （0.49-1.19μg/L）. In summer, weak DVM was limited to cold waters beneath the thermocline for adult females （〈30 ind./m3）, but not for adult males. The maximum abundance of CI-CIV also occurred consistently in the subsurface layer （20-40 m） together with high concentrations of Chl-a （0.81-2.36 μg/L）. CV individuals （1-272 ind./m3） moved slightly upward noc- turnally to the near-surface layer （10-20 m）, where the average temperature was 25.74℃, but they were not found in the surface layer （0-10 m; 28.31℃）. These results indicate that the existence of the YSBCW affected food availability at depth and the vertical temperature distribution, leading to variation in the amplitude and shape of stage-specific vertical distributions （CI to adults） in C. sinicus before and during the formation of cold waters in the Yellow Sea during the study period.
文摘The sensitivity of freshwater invertebrates to agricultural pollutants is supposed to increase with rising temperature due to global warming. The aim of this study was to measure the effect of temperature on the lethal toxicity of ammonia-N, the herbicide Imazamox and the mixture of the two chemicals, in the adults and the juveniles of a population of the copepod Eucyc- lops serrulatus. This is a widely distributed species found in surface waters, in transitional habitats between surface water and groundwater, and in genuine groundwater environments. We tested the sensitivity by short-term bioassays （96 h） at 15℃ and 18℃, respectively. Our results highlighted the following： （1） increasing temperature affected the sensitivity of the adults to am- monia-N and of the juveniles to the mixture, all of which were more sensitive to its detrimental effects at 18~C; （2） the juvenile stages were more sensitive than the adults to all toxicants, and （3） for all combinations of chemicals and temperatures, the effects were synergistic and approximately one order of magnitude greater than those expected according to a concentration addition model when comparing the LC50 for each chemical in the mixture with the LC50s of chemicals individually assayed. Overall, in a context of global change, ammonia-N and mixtures of agricultural pollutants may affect the survival rate of species that spend a part or the whole life-cycle in the hyporheic habitat, with detrimental effects to biodiversity and ecosystem services provided by the hyporheic biota [Current Zoology 61 （4）： 629~540, 2015].
