Phytoplankton are central components of marine environments,and are major players in the production and respiration budgeting.However,their diversity and distribution patterns are still poorly understood due largely t...Phytoplankton are central components of marine environments,and are major players in the production and respiration budgeting.However,their diversity and distribution patterns are still poorly understood due largely to their small sizes and inconspicuous morphology that have been determined via the application of traditional morphology methods over the past two decades.To better understand the composition and diversity of phytoplankton in Jiaozhou Bay,China,seasonal sampling was carried out in 2019 and samples were analyzed with morphological observations and high-throughput sequencing,from which obvious seasonal variations in phytoplankton composition and proportional abundances were uncovered.Metabarcoding revealed far more diversity and species richness of phytoplankton than morphological observations,especially with respect to dinofl agellates.Diatoms were the most dominant phytoplankton group throughout the year,of which Thalassionema and Skeletonema were co-dominant in the bay.Parasitic dinofl agellates(e.g.Amoebophrya),which is often overlooked in the morphological observations,were in dominance and high diversity in the metabarcoding dataset,thus more attention should be paid to exploring the potential role of parasitic dinofl agellates.Temperature,chlorophyll a,and nutrient levels were the main infl uential factors on the distribution of phytoplankton.This study provided a comprehensive morphological and molecular description of phytoplankton and clearly demonstrated the importance of molecular technology in exploring phytoplankton communities.More-widespread use of molecular technology will facilitate deeper understanding of the ecological importance of the diff erent species.展开更多
To better understand the spatial-temporal variation in phytoplankton community structure and its controlling factors in Jiaozhou Bay, Qingdao, North China, four seasonal sampling were carried out in 2017. The phytopla...To better understand the spatial-temporal variation in phytoplankton community structure and its controlling factors in Jiaozhou Bay, Qingdao, North China, four seasonal sampling were carried out in 2017. The phytoplankton community structure and various environmental parameters were examined. The phytoplankton community in the bay was composed of mainly diatoms and dinofl agellates, and several other species of Chrysophyta were also observed. Diatoms were the most dominant phytoplankton group throughout the year, except in spring and winter, when Noctiluca scintillans was co-dominant. High Si/N ratios in summer and fall refl ect the high dominance of diatoms in the two seasons. Temporally, the phytoplankton cell abundance peaked in summer, due mainly to the high temperatures and nutrient concentrations in summer. Spatially, the phytoplankton cell abundance was higher in the northern part of the bay than in the other parts of the bay in four seasons. The diatom cell abundances show signifi cant positive correlations with the nutrient concentrations, while the dinofl agellate cell abundances show no correlation or a negative correlation with the nutrient concentrations but a signifi cant positive correlation with the stratifi cation index. This discrepancy was mainly due to the diff erent survival strategies between diatoms and dinofl agellates. The Shannon-Wiener diversity index ( H′) values in the bay ranged from 0.08 to 4.18, which fell in the range reported in historical studies. The distribution pattern of H′ values was quite diff erent from that of chlorophyll a , indicating that the phytoplankton community structure might have high biomass with a low diversity index. Compared with historical studies, we believe that the dominant phytoplankton species have been changed in recent years due mainly to the changing environment in the Jiaozhou Bay in recent 30 years.展开更多
Seasonal variations in numerical abundance, cell diameter and population carbon biomass of the heterotrophic dinoflagellate Noctiluca scintillans were studied for 10 years from 2004 to 2013 in Jiaozhou Bay and adjacen...Seasonal variations in numerical abundance, cell diameter and population carbon biomass of the heterotrophic dinoflagellate Noctiluca scintillans were studied for 10 years from 2004 to 2013 in Jiaozhou Bay and adjacent coastal Yellow Sea, China, and their ecological functions were evaluated. In both areas, N. scintillans occurred throughout the year and demonstrated an essentially similar seasonality; the cell abundance increased rapidly from the winter minimum to an annual peak in late spring and early summer, and decreased gradually toward the autumn-winter minimum. The peak abundance differed by years, and there was no consistent trend in long-term numerical variations. The cell diameter also showed a seasonal fluctuation, being larger in spring and early summer than the other seasons. Estimated carbon biomass of N. scintillans population reached to a peak as high as 90.3 mg C/m^3, and occasionally exceed over phytoplankton and copepod biomass. Our results demonstrate that N. scintillans in northwestern Yellow Sea displays the seasonal phenology almost identical to the populations in other temperate regions, and play important trophic roles as a heterotroph to interact with sympatric phytoplankton and copepods.展开更多
The fatty acid compositions of seston and Calanus sinicus were investigated to study trophic relationships in Jiaozhou Bay. Principal component analysis was carried out to ordinate the fatty acid patterns of seston in...The fatty acid compositions of seston and Calanus sinicus were investigated to study trophic relationships in Jiaozhou Bay. Principal component analysis was carried out to ordinate the fatty acid patterns of seston in stations and months. The results showed that diatoms were most abundant in the phytoplankton at station A5 （located in the northwest of the bay： 36~9＇N, 120~20＇E） and least abundant at station D7 （located outside of the bay： 35~59＇N, 120~26＇E）. By contrast, dinoflagellates were most abundant at station D7 and least abundant at station A5. According to the annual variations of 16：1 （o7 and 18：4（o3/ 16：1（o7, diatoms flourished mainly in spring and summer, while dinoflagellates bloomed exclusively in summer. A distinctive feature of the fatty acid composition of C. sinicus was the prevalence of 20：5o3 and 22：6（o3. The higher content of 16：1（o7 over 18：4（o3 in females indicated that diatoms contributed more than dinoflagellates to the diet of C. sinicus. The feeding intensity of C. sinicus on diatoms was higher in spring and autumn than in other seasons. The herbivorous indicators 20：1 and 22：1 were comparatively low, suggesting that besides phytoplankton, C. sinicus might feed on a wider range of particles including organic detritus, bacteria and small copepods.展开更多
We used long term monitoring data to evaluate changes in abundance and species dominance of small-jellyfish (collected with zooplankton net whose bell diameter was less than 5 cm) between 1991 and 2009 in the Jiaozhou...We used long term monitoring data to evaluate changes in abundance and species dominance of small-jellyfish (collected with zooplankton net whose bell diameter was less than 5 cm) between 1991 and 2009 in the Jiaozhou Bay, China. Zooplankton samples were vertically towed with conical plankton net from near-bottom to surface, identified microscopically, and mapped in time-space using Grapher 7.0 and Surfer 8.0. Results show that the abundance of small-jellyfish throughout the bay had been increasing during 2001-2009 on average of 15.2 ind./m 3 , almost 5 times higher than that between 1991 and 2000. The occurrence of peak abundance shifted from spring to summer after 2000, and two peaks appeared in spring and summer, respectively, after 2005. Both the abundance and the frequency of blooms of small-jellyfish increased after 2000 in the bay. In addition, the biodiversity of jellyfish has increased significantly in recent years with a change in dominant species. Several new dominant species appeared after 2000, including Rathkae octopunctata in winter, Phialidium hemisphaericum in spring, summer, and autumn, Phialucium carolinae in spring, and Pleurobrachia globosa in summer and autumn, while some previous dominant species throughout the 1990s (Eirene ceylonensis, Zanclea costata, Lovenella assimilis, and Muggiaea atlantica) were no longer dominant after 2000. The abundance of small-jellyfish was positively correlated with the density of dinoflagellates, and the abundance of zooplankton. We believe that the changes in smalljellyfish abundance and species composition were the result of eutrophication, aquaculture and coastal construction activities around the bay. Concurrently, seawater warming and salinity decrease in recent decades promoted the growth and reproduction of small-jellyfish in the bay.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
Zooplankton abundance, biovolume and taxonomic composition in Jiaozhou Bay and the adjacent coastal Yellow Sea were evaluated using ZooScan measurement of samples collected by net towing every August from 2005 to 2012...Zooplankton abundance, biovolume and taxonomic composition in Jiaozhou Bay and the adjacent coastal Yellow Sea were evaluated using ZooScan measurement of samples collected by net towing every August from 2005 to 2012. Zooplankton abundance and biovolume ranged from 1 938.5 to 24 800 ind./m^3 and 70.8 to 1 480.1 mm^3/m^3 in Jiaozhou Bay and 73.1 to 16 814.3 ind./m^3 and 19.6 to 640.7 mm^3/m^3 in the coastal Yellow Sea. Copepods were the most abundant group in both regions, followed by N octiluca scintillans and appendicularians in Jiaohzou Bay, and chaetognaths and N octiluca scintillans in adjacent coastal Yellow Sea. Over the study period, the most conspicuous hydrographic change was an increase in water temperature. Meanwhile, a general decrease in zooplankton abundance was observed, particularly in copepod populations. Based on redundancy analysis(RDA), the warming trend was the key environmental factor influencing to decrease of copepod abundance. The proportion of small-sized copepods increased while the mean size of all copepods decreased, in significant correlation with water temperature. Our results indicate that zooplankton, particularly copepods, are highly sensitive to change in water temperature, which is consistent with predicted impacts of warming on aquatic ectotherms. Due to their dominance in the zooplankton, the decline in copepod size and abundance could lead to an unfavourable decrease in energy availability for predators, particularly planktivorous fish.展开更多
As an emerging pollutant,the presence of microplastics in marine organisms has been concerned increasingly.Shellfi sh,which are both economically and ecologically important,are of particular concern.In this study,we i...As an emerging pollutant,the presence of microplastics in marine organisms has been concerned increasingly.Shellfi sh,which are both economically and ecologically important,are of particular concern.In this study,we investigated the microplastic pollution in wild and farmed oysters(Crassostrea gigas)and clams(Ruditapes philippinarum)in the Jiaozhou Bay,China,for the fi rst time.We found the microplastic pollution in shellfi sh in Jiaozhou Bay was at a moderate level.The abundance of microplastics in shellfi sh ranged from 0.16 to 12.09 items/g(wet weight,ww)or 1 to 9 items/ind.The average abundance of the ingested microplastics was 1.21 items/g(or 2.17 items/ind.)in all shellfi sh,1.51 items/g(or 2.00 items/ind.)in clams and 0.92 items/g(or 2.34 items/ind.)in oysters.The abundance of microplastics in clams was signifi cantly higher than that in oysters.Most microplastics(92.97%)were fi bers,followed by fragments.The predominant color of the microplastics was black(42.97%),followed by blue,transparent,and red.Cellophane and polyethylene terephthalate(PET)dominated the microplastic composition.According to shellfi sh consumption,it can be inferred that the average microplastic consumption through Chinese diet is 1.27×10^(3)items per capita per year.展开更多
The population explosion of jellyfish Aurelia coerulea occurred in Jiaozhou Bay,China in 2009.The potential predation impact of A.coerulea on zooplankton was investigated.Population clearance potential and residence t...The population explosion of jellyfish Aurelia coerulea occurred in Jiaozhou Bay,China in 2009.The potential predation impact of A.coerulea on zooplankton was investigated.Population clearance potential and residence time(t 1/2)for copepods were calculated from laboratory clearance rates and measurements of jellyfish size and abundance from May to August 2009 in Jiaozhou Bay.Clearance rates varied widely with prey organisms,but they were not significantly different among various prey concentrations.Medusae captured rotifers,fish larvae and hydromedusae more efficiently than fish eggs,copepods and chaetognaths.Ephyrae captured rotifers and hydromedusae more efficiently than fish larvae and copepods.Clearance rate linearly increased with the cross sectional area of A.coerulea(size from 0.3 to 7.1 cm).Water temperature also had a marked effect on clearance rate and this was related to the increased beat frequency as water temperature increased.In early May 2009,A.coerulea potentially cleared the volume of water in the Bay less than 0.001 times a day,but this value was estimated to be more than 0.3 times a day in July.The t 1/2 for copepods was less than 6 d in June and July.Abundances of copepods,hydromedusae and chaetognaths were extremely low in 2009 compared to 2008 and 2010(jellyfish non-bloom years).Large predation pressure by the A.coerulea population occurred to control zooplankton communities in Jiaozhou Bay.A.coerulea,when present at a high population level,can be a keystone species in Jiaozhou Bay and control the trophic structure here.展开更多
The dead proportion of a calanoid copepod Calanus sinicus population was investigated monthly with neutral red staining method at 12 stations in the Jiaozhou Bay and the adjacent waters from December 2008 to November ...The dead proportion of a calanoid copepod Calanus sinicus population was investigated monthly with neutral red staining method at 12 stations in the Jiaozhou Bay and the adjacent waters from December 2008 to November 2009. C. sinicus could be observed through the whole year, with an evident numerical peak from February to April and an extremely low abundance in summer. Annual variation of the dead proportion differed greatly between adult females and copepodites. Dead females were observed only in the southern part and outside the bay sporadically in five months, when the egg production was the most active. Dead proportion of females was usually less than 5%. Dead copepodites could be observed in all but three months in summer in the whole study area, and the proportion varied between 3.8% – 18.2%. Death percentage of copepodites increased significantly in the northern part in January and June, when water temperature exceeded it's favorable limits;however, the fluctuated salinity had no significant effect on the survival of both females and copepodites. Thus the dead proportion of C. sinicus was relatively low in the Jiaozhou Bay, while difference could be observed between females and copepodites. Dead copepodites were common in all samples, but dead females were presented mainly as ‘reproduction cost' during generation alternation.展开更多
Carbon biomass,carbon-to-chlorophyll a ratio(C꞉Chl a),and the growth rate of phytoplankton cells were studied during four seasonal cruises in 2017 and 2018 in Jiaozhou Bay,China.Water samples were collected from 12 st...Carbon biomass,carbon-to-chlorophyll a ratio(C꞉Chl a),and the growth rate of phytoplankton cells were studied during four seasonal cruises in 2017 and 2018 in Jiaozhou Bay,China.Water samples were collected from 12 stations,and phytoplankton carbon biomass(phyto-C)was estimated from microscope-measured cell volumes.The phyto-C ranged from 5.05 to 78.52μg C/L in the bay,and it constituted a mean of 38.16% of the total particulate organic carbon in the bay.High phyto-C values appeared mostly in the northern or northeastern bay.Diatom carbon was predominant during all four cruises.Dinoflagellate carbon contributed much less(<30%)to the total phyto-C,and high values appeared often in the outer bay.The C꞉Chl a of phytoplankton cells varied from 11.50 to 61.45(mean 31.66),and high values appeared in the outer bay during all four seasons.The phyto-C was also used to calculate the intrinsic growth rates of phytoplankton cells in the bay,and phytoplankton growth rates ranged from 0.56 to 1.96/d;the rate was highest in summer(mean 1.79/d),followed by that in fall(mean 1.24/d)and spring(mean 1.17/d),and the rate was lowest in winter(mean 0.77/d).Temperature and silicate concentration were found to be the determining factors of phytoplankton growth rates in the bay.To our knowledge,this study is the first report on phytoplankton carbon biomass and C꞉Chl a based on water samples in Jiaozhou Bay,and it will provide useful information for studies on carbon-based food web calculations and carbon-based ecosystem models in the bay.展开更多
Population dynamics of four dominant Antarctic copepods, Calanoides acutus, Calanus propinquus, Metridia gerlachei and Rhincalanus gigas were studied based on zooplankton samples collected in the Prydz Bay during aust...Population dynamics of four dominant Antarctic copepods, Calanoides acutus, Calanus propinquus, Metridia gerlachei and Rhincalanus gigas were studied based on zooplankton samples collected in the Prydz Bay during austral summer from 1999 to 2006. We found that C. acutus was the most abundant species among these four copepods, followed by C. propinquus, M. gerlachei and R. gigas. R. gigas occurred mainly in the warmer oceanic regions and showed distribution patterns discrete from the other three species, whose distribution in the whole survey area overlapped. By December 15th （about one month before our sampling） of the years 1999, 2003 and 2006, sea ice retreated earlier and polynyas existed in the neritic region one month before sampling. These periods were characterized by numerical dominance of C. acutus, C. propinquus and M. gerlachei, elevated proportions of Copepodite I and Copepodite II stages especially in the neritic region. While for the years 2000, 2002, and 2005, the ice edge located more northerly and polynyas did not exist in the neritic region, the copepods abundance was lower, indicating poor recruitment. Population structure of R. gigas was mainly composed of advanced stages Copepodite V and female during all cruises. Log10 （x＋l） transformed densities of C. acutus, C. propinquus and M. gerlachei showed positive correlation with temperature and chlorophyll a concentration, while mean population stages of these copopods were negatively correlated with these environmental variables. Younger copepodite stages of C. acutus, C. propinquus and M. gerlachei appeared more often in neritic regions. We confirmed that the polynyas had a great contribution to phytoplankton blooms, which promote copepods reproduction and recruitment success. The study suggested that population dynamics of the four copepods have good correspondence with sea ice and polynya variations during all cruises of the Prydz Bay.展开更多
Quantifying the gross and net production is an essential component of carbon cycling and marine ecosystem studies.Triple oxygen isotope measurements and the O_(2)/Ar ratio are powerful indices in quantifying the gross...Quantifying the gross and net production is an essential component of carbon cycling and marine ecosystem studies.Triple oxygen isotope measurements and the O_(2)/Ar ratio are powerful indices in quantifying the gross primary production and net community production of the mixed layer zone,respectively.Although there is a substantial advantage in refining the gas exchange term and water column vertical mixing calibration,application of mixed layer depth history to the gas exchange term and its contribution to reducing indices error are unclear.Therefore,two cruises were conducted in the slope regions of the northern South China Sea in October 2014(autumn)and June 2015(spring).Discrete water samples at Station L07 in the upper 150 m depth were collected for the determination ofδ^(17)0,δ^(18)O,and the O_(2)/Ar ratio of dissolved gases.Gross oxygen production(GOP)was estimated using the triple oxygen isotopes of the dissolved O_(2),and net oxygen production(NOP)was calculated using O_(2)/Ar ratio and O_(2)concentration.The vertical mixing effect in NOP was calibrated via a N_(2)O based approach.GOP for autumn and spring was(169±23)mmol/(m^(2)·d)(by O_(2))and(189±26)mmol/(m^(2)·d)(by O_(2)),respectively.While NOP was 1.5 mmol/(m^(2)·d)(by O_(2))in autumn and 8.2 mmol/(m^(2)·d)(by O_(2))in spring.Application of mixed layer depth history in the gas flux parametrization reduced up to 9.5%error in the GOP and NOP estimations.A comparison with an independent O_(2)budget calculation in the diel observation indicated a26%overestimation in the current GOP,likely due to the vertical mixing effect.Both GOP and NOP in June were higher than those in October.Potential explanations for this include the occurrence of an eddy process in June,which may have exerted a submesoscale upwelling at the sampling station,and also the markedly higher terrestrial impact in June.展开更多
Herbivore digestion in aquatic ecosystems is usually considered a method of nutrient repackaging rather than recycling,as recalcitrant and low-level nutrients are presumed for their egesta.We hypothesize that this opi...Herbivore digestion in aquatic ecosystems is usually considered a method of nutrient repackaging rather than recycling,as recalcitrant and low-level nutrients are presumed for their egesta.We hypothesize that this opinion holds only for nutrients recycled by excretion and egestion,not for those elements recycled overwhelmingly by fecal decomposition.In this study,we compared the dissolution of biogenic silica(BSi),phosphorus(P)and iron(Fe)between two food items and fecal pellets of two marine invertebrates fed on artificial seawaters free of bacteria.Relative to raw food materials,the mass proportion in fecal pellets of BSi increased,while that of P and Fe decreased.During the 21 days of incubation,the total dissolution rate of BSi was 13.9–36.0 times higher in fecal pellets than food items,followed by P(1.5–4.2 times)and Fe(1.1–2.4 times).While the dissolution of BSi and Fe occurred mostly in the first few days,P was mostly released in the last ten days.Regarding BSi dissolution,a higher rate was observed in oyster Crassostrea gigas than the Echiuran Urechis unicinctus,but no significant difference was found between fecal pellets in either species under naturally available diatom food(Phaeodactylum tricornutum)and introduced terrestrial food(rice husk powder),respectively.Our results show direct evidence of digestion-associated nutrients mobilization.BSi dissolution after animal digestion may be similarly efficient to that caused by bacteria colonization in natural seawater.展开更多
The distribution and abundance of euphausiid larvae and salps was studied from samples collected in 2002 and 2006 from Prydz Bay.Antarctica. Larvae of Thysanoessa macrura and Euphausia superba were mainly distributed ...The distribution and abundance of euphausiid larvae and salps was studied from samples collected in 2002 and 2006 from Prydz Bay.Antarctica. Larvae of Thysanoessa macrura and Euphausia superba were mainly distributed in the north of the continental shelf.T.macrura was more abundant and had a relatively wider distribution.In 2006,with ice having retreated and higher seawater temperatures and chlorophyll a levels,E.superba and T.macrura occurred in higher abundances and at more mature developmental stages.Euphausia crystallorophias was mainly distributed in the neritic region.In 2002,with severe ice conditions in the neritic region,abundance of E.crystallorophias was only 95.6 ind·（1000 m）^（-3）.In 2006 when a polynya existed,the abundance of E.crystallorophias reached 43966.6 ind·（1000 m）^（-3）.The population mainly consisted of metanauplius（MN） and calyptopis I（CD.Salps,mostly Salpa thompsoni,had a low abundance in Prydz Bay.In 2002,S.thompsoni was only found at one station in the north of the bay with an abundance of 10 ind·（1000 m）^（-3）.In 2006,S.thompsoni was found at three stations located near the continental slope and average abundance reached 146.7 ind·（1000 m）^（-3）.Environmental factors,such as the timing of ice melt,polynya formation and food concentration appear to have a marked effect on the distribution and abundance of euphausiid larvae and salps.展开更多
Ulva prolifera is the causative species of the annually occurring large-scale green tides in China since 2007.Its specific biological features on reproductivity strategies,as well as intra-species genetic diversity,ar...Ulva prolifera is the causative species of the annually occurring large-scale green tides in China since 2007.Its specific biological features on reproductivity strategies,as well as intra-species genetic diversity,are still largely unknown,especially at the genome level,despite their importance in understanding the formation and outbreak of massive green tides.In the present study,the restriction site-associated DNA genotyping approach(2b-RAD)was adopted to identify the genome-wide single-nucleotide polymorphisms(SNPs)of 54 individual thalli including samples collected from Subei Shoal in 2019 and Qingdao coast from 2019 to 2021.SNPs genotype results revealed that most of the thalli in 2019 and 2020 were haploid gametophytes,while only half of the thalli were gametophytes in 2021,indicating flexibility in the reproductive strategies for the formation of the green tides among different years and the dominance of asexual and vegetative reproductive mode for the floating period.Besides,population analysis was conducted,and it revealed a very low genetic diversity among samples from Subei Shoal and the Qingdao coast in the same year and a higher divergence among samples in different years.The results showed the efficiency of 2b-RAD in the exploration of SNPs in U.prolifera and provided the first genome-wide scale evidence for the origin of the large-scale green tides on the Qingdao coast.This study improved our understanding of the reproductive strategy and genetic diversity of the green tide causative species and will help further reveal the biological causes of the green tide in China.展开更多
Meroplankton play a crucial role in both benthic and pelagic ecosystems.Existing quantitative research on estimating the quantities of meroplankton groups is both underrepresented and inaccurate.To investigate and eva...Meroplankton play a crucial role in both benthic and pelagic ecosystems.Existing quantitative research on estimating the quantities of meroplankton groups is both underrepresented and inaccurate.To investigate and evaluate the influence of varying mesh sizes(505 and 160μm)on the sampling efficiency of meroplankton,we conducted an examination using two commonly used plankton nets during the spring season in the Southern Yellow Sea(SYS).Our study revealed a total of 12 meroplankton groups,with 9 groups identified in the 505-μm mesh nets and 11 groups in the 160-μm mesh nets.The results demonstrated the superior collection efficiency of the 160-μm net compared to the 505-μm net across the majority of meroplankton groups.Furthermore,we focused on exploring the abundance,distribution patterns,and realized niches of meroplankton collected by the two mesh size nets,and observed that the distribution of meroplankton closely resembled the distribution of possible benthic adults in the SYS.Correlation analysis of the six dominant groups collected in the 160-μm mesh nets revealed that seawater temperature and salinity emerged as the key environmental factors driving variations in meroplankton abundance within the SYS.This study also found that a smaller mesh size net does not necessarily capture meroplankton more comprehensively.A comprehensive understanding of the ecological characteristics of meroplankton requires the combination of two types of nets for research.Our research significantly advances our understanding of the quantification,abundance,and distribution of meroplankton,serving as a valuable contribution to the broader landscape of detailed quantitative meroplankton studies.展开更多
Cyanea nozakii,a common jellyfish distributed in offshore China,has a complex trophic relationship with other zooplankton groups.However,few studies have reported the predation rates and prey selection patterns of C.n...Cyanea nozakii,a common jellyfish distributed in offshore China,has a complex trophic relationship with other zooplankton groups.However,few studies have reported the predation rates and prey selection patterns of C.nozakii medusae on different prey items.Research is also lacking on the intraguild predation of Aurelia coerulea(another common bloom jellyfish in offshore China)by C.nozakii.To address the knowledge gaps,the clearance rates of C.nozakii for different prey items,including copepods(small<1000μm and large>1000μm),fish larvae,and gelatinous prey(hydromedusae,A.coerulea ephyrae,and chaetognaths),were measured.The influence of predator size on the clearance rate was also determined.Additionally,we examined the intraguild predation of C.nozakii on A.coerulea medusae.The clearance rates of C.nozakii varied widely with prey organisms,being independent of prey concentrations.Gelatinous organisms,except for chaetognaths,were captured with considerably high efficiency,followed by fish larvae and copepods,indicating the preferential prey selection of gelatinous organisms by C.nozakii.The clearance rate increased linearly with the cross-sectional area of C.nozakii.Body size in medusae may,to some extents,underpin their capacity to capture more prey by increasing the encounter rate and capture success through ontogeny.C.nozakii preyed voraciously on A.coerulea in high feeding efficiency,but the clearance rate decreased with increasing A.coerulea(as prey)size.This phenomenon of intraguild predation suggests a speculative hypothesis of potential population regulation of A.coerulea by C.nozakii.The information regarding the feeding ecology of C.nozakii reported in this study is important for understanding plankton dynamics in marine ecosystems with extensive occurrences of this jellyfish.展开更多
The Yellow Sea(YS)and East China Sea(ECS)are highly dynamic marginal seas of the northwestern Pacific Ocean.To gain an in-depth understanding of zooplankton community structure,zooplankton abundance,biovolume,and size...The Yellow Sea(YS)and East China Sea(ECS)are highly dynamic marginal seas of the northwestern Pacific Ocean.To gain an in-depth understanding of zooplankton community structure,zooplankton abundance,biovolume,and size structure in summer 2017 in the YS and ECS were assessed using ZooScan imaging analysis.Zooplankton abundance and biovolume ranged 2.94–1187.14 inds./m^(3)and 3.13–3438.51 mm^(3)/m^(3),respectively.Based on the biovolume data of the categorized size classes of 26 identified taxonomic groups,the zooplankton community was classified into five groups,and each group was coupled with distinctive oceanographic features.Under the influence of the Yellow Sea Cold Water Mass,the Yellow Sea offshore group featured the lowest bottom temperature(10.84±3.42℃)and the most abundant Calanoids(mainly in the 2–3 mm size class).In the Yellow Sea inshore group,Hydrozoans showed the largest biovolume and dominated in the 3–4-mm and>5-mm size classes.The East China Sea offshore group,which was affected by the Kuroshio Branch Current,featured high temperature and salinity,and the lowest bottom dissolved oxygen(2.58±0.5 mg/L).The lowest values of zooplankton abundance and biovolume in the East China Sea offshore group might be attributed to the bottom dissolved oxygen contents.The East China Sea inshore group,which was mainly influenced by the Zhejiang-Fujian Coastal Current and Changjiang Diluted Water,was characterized by high chlorophyll a and the largest biovolume of carnivorous Siphonophores(280.82±303.37 mm^(3)/m^(3)).The Changjiang River estuary offshore group showed the most abundant Cyclopoids,which might be associated with the less turbid water mass in this region.Seawater temperature was considered the most important factor in shaping the size compositions of Calanoids in different groups.展开更多
As a National Basic Research Program (973 Program) of China, the Key Processes, Mechanism and Ecological Consequences of Jellyfish Bloom in China Coastal Waters led by Prof. SUN
基金Supported by the National Science Foundation of China(NSFC)(Nos.41876120,41906122,41606128,U1706218)the Science&Technology Basic Resources Investigation Program of China(No.2018FY100200)。
文摘Phytoplankton are central components of marine environments,and are major players in the production and respiration budgeting.However,their diversity and distribution patterns are still poorly understood due largely to their small sizes and inconspicuous morphology that have been determined via the application of traditional morphology methods over the past two decades.To better understand the composition and diversity of phytoplankton in Jiaozhou Bay,China,seasonal sampling was carried out in 2019 and samples were analyzed with morphological observations and high-throughput sequencing,from which obvious seasonal variations in phytoplankton composition and proportional abundances were uncovered.Metabarcoding revealed far more diversity and species richness of phytoplankton than morphological observations,especially with respect to dinofl agellates.Diatoms were the most dominant phytoplankton group throughout the year,of which Thalassionema and Skeletonema were co-dominant in the bay.Parasitic dinofl agellates(e.g.Amoebophrya),which is often overlooked in the morphological observations,were in dominance and high diversity in the metabarcoding dataset,thus more attention should be paid to exploring the potential role of parasitic dinofl agellates.Temperature,chlorophyll a,and nutrient levels were the main infl uential factors on the distribution of phytoplankton.This study provided a comprehensive morphological and molecular description of phytoplankton and clearly demonstrated the importance of molecular technology in exploring phytoplankton communities.More-widespread use of molecular technology will facilitate deeper understanding of the ecological importance of the diff erent species.
基金Supported by the National Natural Science Foundation of China(Nos.31700425,91751202)the Innovation Plan of Science and Technology for Aoshan(No.2016ASKJ02)the Health Assessment and Decision Support System for Coastal Ecosystem(No.XDA19060204)
文摘To better understand the spatial-temporal variation in phytoplankton community structure and its controlling factors in Jiaozhou Bay, Qingdao, North China, four seasonal sampling were carried out in 2017. The phytoplankton community structure and various environmental parameters were examined. The phytoplankton community in the bay was composed of mainly diatoms and dinofl agellates, and several other species of Chrysophyta were also observed. Diatoms were the most dominant phytoplankton group throughout the year, except in spring and winter, when Noctiluca scintillans was co-dominant. High Si/N ratios in summer and fall refl ect the high dominance of diatoms in the two seasons. Temporally, the phytoplankton cell abundance peaked in summer, due mainly to the high temperatures and nutrient concentrations in summer. Spatially, the phytoplankton cell abundance was higher in the northern part of the bay than in the other parts of the bay in four seasons. The diatom cell abundances show signifi cant positive correlations with the nutrient concentrations, while the dinofl agellate cell abundances show no correlation or a negative correlation with the nutrient concentrations but a signifi cant positive correlation with the stratifi cation index. This discrepancy was mainly due to the diff erent survival strategies between diatoms and dinofl agellates. The Shannon-Wiener diversity index ( H′) values in the bay ranged from 0.08 to 4.18, which fell in the range reported in historical studies. The distribution pattern of H′ values was quite diff erent from that of chlorophyll a , indicating that the phytoplankton community structure might have high biomass with a low diversity index. Compared with historical studies, we believe that the dominant phytoplankton species have been changed in recent years due mainly to the changing environment in the Jiaozhou Bay in recent 30 years.
基金Supported by the State Key Program of National Natural Science Foundation of China(No.41230963)the NSFC-Shandong Joint Fund for Marine Ecology and Environmental Sciences(No.U1606404)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA11020305)the President’s International Fellowship Initiative(PIFI)of the Chinese Academy of Sciences(No.2016VBA078)to SUNSong
文摘Seasonal variations in numerical abundance, cell diameter and population carbon biomass of the heterotrophic dinoflagellate Noctiluca scintillans were studied for 10 years from 2004 to 2013 in Jiaozhou Bay and adjacent coastal Yellow Sea, China, and their ecological functions were evaluated. In both areas, N. scintillans occurred throughout the year and demonstrated an essentially similar seasonality; the cell abundance increased rapidly from the winter minimum to an annual peak in late spring and early summer, and decreased gradually toward the autumn-winter minimum. The peak abundance differed by years, and there was no consistent trend in long-term numerical variations. The cell diameter also showed a seasonal fluctuation, being larger in spring and early summer than the other seasons. Estimated carbon biomass of N. scintillans population reached to a peak as high as 90.3 mg C/m^3, and occasionally exceed over phytoplankton and copepod biomass. Our results demonstrate that N. scintillans in northwestern Yellow Sea displays the seasonal phenology almost identical to the populations in other temperate regions, and play important trophic roles as a heterotroph to interact with sympatric phytoplankton and copepods.
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(No.KZCX2-YW-213-3)the National Natural Science Foundation of China(Nos.40776092,40821004)
文摘The fatty acid compositions of seston and Calanus sinicus were investigated to study trophic relationships in Jiaozhou Bay. Principal component analysis was carried out to ordinate the fatty acid patterns of seston in stations and months. The results showed that diatoms were most abundant in the phytoplankton at station A5 （located in the northwest of the bay： 36~9＇N, 120~20＇E） and least abundant at station D7 （located outside of the bay： 35~59＇N, 120~26＇E）. By contrast, dinoflagellates were most abundant at station D7 and least abundant at station A5. According to the annual variations of 16：1 （o7 and 18：4（o3/ 16：1（o7, diatoms flourished mainly in spring and summer, while dinoflagellates bloomed exclusively in summer. A distinctive feature of the fatty acid composition of C. sinicus was the prevalence of 20：5o3 and 22：6（o3. The higher content of 16：1（o7 over 18：4（o3 in females indicated that diatoms contributed more than dinoflagellates to the diet of C. sinicus. The feeding intensity of C. sinicus on diatoms was higher in spring and autumn than in other seasons. The herbivorous indicators 20：1 and 22：1 were comparatively low, suggesting that besides phytoplankton, C. sinicus might feed on a wider range of particles including organic detritus, bacteria and small copepods.
基金Supported by the National Basic Research Program of China (973 Program) (No. 2011CB403601)the Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX2-YW-Q07-01)+2 种基金the External Cooperation Program of Chinese Academy of Sciences (No. GJHZ200808)the National Natural Science Foundation of China (No. 40876083)the Ocean Public Welfare Scientific Research Project, State Oceanic Administration of China (No. 201005014)
文摘We used long term monitoring data to evaluate changes in abundance and species dominance of small-jellyfish (collected with zooplankton net whose bell diameter was less than 5 cm) between 1991 and 2009 in the Jiaozhou Bay, China. Zooplankton samples were vertically towed with conical plankton net from near-bottom to surface, identified microscopically, and mapped in time-space using Grapher 7.0 and Surfer 8.0. Results show that the abundance of small-jellyfish throughout the bay had been increasing during 2001-2009 on average of 15.2 ind./m 3 , almost 5 times higher than that between 1991 and 2000. The occurrence of peak abundance shifted from spring to summer after 2000, and two peaks appeared in spring and summer, respectively, after 2005. Both the abundance and the frequency of blooms of small-jellyfish increased after 2000 in the bay. In addition, the biodiversity of jellyfish has increased significantly in recent years with a change in dominant species. Several new dominant species appeared after 2000, including Rathkae octopunctata in winter, Phialidium hemisphaericum in spring, summer, and autumn, Phialucium carolinae in spring, and Pleurobrachia globosa in summer and autumn, while some previous dominant species throughout the 1990s (Eirene ceylonensis, Zanclea costata, Lovenella assimilis, and Muggiaea atlantica) were no longer dominant after 2000. The abundance of small-jellyfish was positively correlated with the density of dinoflagellates, and the abundance of zooplankton. We believe that the changes in smalljellyfish abundance and species composition were the result of eutrophication, aquaculture and coastal construction activities around the bay. Concurrently, seawater warming and salinity decrease in recent decades promoted the growth and reproduction of small-jellyfish in the bay.
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Supported by the State Key Program of National Natural Science Foundation of China(No.41230963)the NSFC-Shandong Joint Fund for Marine Ecology and Environmental Sciences(No.U1606404)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA11020305)to SUN Song
文摘Zooplankton abundance, biovolume and taxonomic composition in Jiaozhou Bay and the adjacent coastal Yellow Sea were evaluated using ZooScan measurement of samples collected by net towing every August from 2005 to 2012. Zooplankton abundance and biovolume ranged from 1 938.5 to 24 800 ind./m^3 and 70.8 to 1 480.1 mm^3/m^3 in Jiaozhou Bay and 73.1 to 16 814.3 ind./m^3 and 19.6 to 640.7 mm^3/m^3 in the coastal Yellow Sea. Copepods were the most abundant group in both regions, followed by N octiluca scintillans and appendicularians in Jiaohzou Bay, and chaetognaths and N octiluca scintillans in adjacent coastal Yellow Sea. Over the study period, the most conspicuous hydrographic change was an increase in water temperature. Meanwhile, a general decrease in zooplankton abundance was observed, particularly in copepod populations. Based on redundancy analysis(RDA), the warming trend was the key environmental factor influencing to decrease of copepod abundance. The proportion of small-sized copepods increased while the mean size of all copepods decreased, in significant correlation with water temperature. Our results indicate that zooplankton, particularly copepods, are highly sensitive to change in water temperature, which is consistent with predicted impacts of warming on aquatic ectotherms. Due to their dominance in the zooplankton, the decline in copepod size and abundance could lead to an unfavourable decrease in energy availability for predators, particularly planktivorous fish.
基金Supported by the International Science Partnership Program of the Chinese Academy of Sciences(Nos.121311KYSB20190029,133137KYSB20200002)the Joint Funds of the National Natural Science Foundation of China(No.U2006206)the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDA19060204,XDA23050303),and the Project from Shandong Academy for Environmental Planning:Research on the Prevention and Control of Marine Microplastic Pollution in Key Industries in Shandong Province。
文摘As an emerging pollutant,the presence of microplastics in marine organisms has been concerned increasingly.Shellfi sh,which are both economically and ecologically important,are of particular concern.In this study,we investigated the microplastic pollution in wild and farmed oysters(Crassostrea gigas)and clams(Ruditapes philippinarum)in the Jiaozhou Bay,China,for the fi rst time.We found the microplastic pollution in shellfi sh in Jiaozhou Bay was at a moderate level.The abundance of microplastics in shellfi sh ranged from 0.16 to 12.09 items/g(wet weight,ww)or 1 to 9 items/ind.The average abundance of the ingested microplastics was 1.21 items/g(or 2.17 items/ind.)in all shellfi sh,1.51 items/g(or 2.00 items/ind.)in clams and 0.92 items/g(or 2.34 items/ind.)in oysters.The abundance of microplastics in clams was signifi cantly higher than that in oysters.Most microplastics(92.97%)were fi bers,followed by fragments.The predominant color of the microplastics was black(42.97%),followed by blue,transparent,and red.Cellophane and polyethylene terephthalate(PET)dominated the microplastic composition.According to shellfi sh consumption,it can be inferred that the average microplastic consumption through Chinese diet is 1.27×10^(3)items per capita per year.
基金the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.2018SDKJ0504-3)the National Key Research and Development Program of China(No.2017YFC1404405)Mount Tai Scholar Climbing Plan to SUN Song。
文摘The population explosion of jellyfish Aurelia coerulea occurred in Jiaozhou Bay,China in 2009.The potential predation impact of A.coerulea on zooplankton was investigated.Population clearance potential and residence time(t 1/2)for copepods were calculated from laboratory clearance rates and measurements of jellyfish size and abundance from May to August 2009 in Jiaozhou Bay.Clearance rates varied widely with prey organisms,but they were not significantly different among various prey concentrations.Medusae captured rotifers,fish larvae and hydromedusae more efficiently than fish eggs,copepods and chaetognaths.Ephyrae captured rotifers and hydromedusae more efficiently than fish larvae and copepods.Clearance rate linearly increased with the cross sectional area of A.coerulea(size from 0.3 to 7.1 cm).Water temperature also had a marked effect on clearance rate and this was related to the increased beat frequency as water temperature increased.In early May 2009,A.coerulea potentially cleared the volume of water in the Bay less than 0.001 times a day,but this value was estimated to be more than 0.3 times a day in July.The t 1/2 for copepods was less than 6 d in June and July.Abundances of copepods,hydromedusae and chaetognaths were extremely low in 2009 compared to 2008 and 2010(jellyfish non-bloom years).Large predation pressure by the A.coerulea population occurred to control zooplankton communities in Jiaozhou Bay.A.coerulea,when present at a high population level,can be a keystone species in Jiaozhou Bay and control the trophic structure here.
基金supported by the National Key Research and Development Program of China (No. 2017YFE111100)the Aoshan Science and Technology Innovation Project (No. 2016ASKJ0202)the National Natural Science Foundation of China (Nos. 41406148,40830854)。
文摘The dead proportion of a calanoid copepod Calanus sinicus population was investigated monthly with neutral red staining method at 12 stations in the Jiaozhou Bay and the adjacent waters from December 2008 to November 2009. C. sinicus could be observed through the whole year, with an evident numerical peak from February to April and an extremely low abundance in summer. Annual variation of the dead proportion differed greatly between adult females and copepodites. Dead females were observed only in the southern part and outside the bay sporadically in five months, when the egg production was the most active. Dead proportion of females was usually less than 5%. Dead copepodites could be observed in all but three months in summer in the whole study area, and the proportion varied between 3.8% – 18.2%. Death percentage of copepodites increased significantly in the northern part in January and June, when water temperature exceeded it's favorable limits;however, the fluctuated salinity had no significant effect on the survival of both females and copepodites. Thus the dead proportion of C. sinicus was relatively low in the Jiaozhou Bay, while difference could be observed between females and copepodites. Dead copepodites were common in all samples, but dead females were presented mainly as ‘reproduction cost' during generation alternation.
基金Supported by the National Natural Science Foundation of China(Nos.31700425,91751202)the External Cooperation Program of Chinese Academy of Sciences(No.133137KYSB20200002)the Taishan Scholars Project to Song SUN。
文摘Carbon biomass,carbon-to-chlorophyll a ratio(C꞉Chl a),and the growth rate of phytoplankton cells were studied during four seasonal cruises in 2017 and 2018 in Jiaozhou Bay,China.Water samples were collected from 12 stations,and phytoplankton carbon biomass(phyto-C)was estimated from microscope-measured cell volumes.The phyto-C ranged from 5.05 to 78.52μg C/L in the bay,and it constituted a mean of 38.16% of the total particulate organic carbon in the bay.High phyto-C values appeared mostly in the northern or northeastern bay.Diatom carbon was predominant during all four cruises.Dinoflagellate carbon contributed much less(<30%)to the total phyto-C,and high values appeared often in the outer bay.The C꞉Chl a of phytoplankton cells varied from 11.50 to 61.45(mean 31.66),and high values appeared in the outer bay during all four seasons.The phyto-C was also used to calculate the intrinsic growth rates of phytoplankton cells in the bay,and phytoplankton growth rates ranged from 0.56 to 1.96/d;the rate was highest in summer(mean 1.79/d),followed by that in fall(mean 1.24/d)and spring(mean 1.17/d),and the rate was lowest in winter(mean 0.77/d).Temperature and silicate concentration were found to be the determining factors of phytoplankton growth rates in the bay.To our knowledge,this study is the first report on phytoplankton carbon biomass and C꞉Chl a based on water samples in Jiaozhou Bay,and it will provide useful information for studies on carbon-based food web calculations and carbon-based ecosystem models in the bay.
基金Supported by National Key Technology Research and Development Program of China (No. 2006BAB18B07)the National Natural Science Foundation of China (No. 40821004)+1 种基金National Polar Project of China (No. JDZX20110016)the China International Polar Year (IPY) Program
文摘Population dynamics of four dominant Antarctic copepods, Calanoides acutus, Calanus propinquus, Metridia gerlachei and Rhincalanus gigas were studied based on zooplankton samples collected in the Prydz Bay during austral summer from 1999 to 2006. We found that C. acutus was the most abundant species among these four copepods, followed by C. propinquus, M. gerlachei and R. gigas. R. gigas occurred mainly in the warmer oceanic regions and showed distribution patterns discrete from the other three species, whose distribution in the whole survey area overlapped. By December 15th （about one month before our sampling） of the years 1999, 2003 and 2006, sea ice retreated earlier and polynyas existed in the neritic region one month before sampling. These periods were characterized by numerical dominance of C. acutus, C. propinquus and M. gerlachei, elevated proportions of Copepodite I and Copepodite II stages especially in the neritic region. While for the years 2000, 2002, and 2005, the ice edge located more northerly and polynyas did not exist in the neritic region, the copepods abundance was lower, indicating poor recruitment. Population structure of R. gigas was mainly composed of advanced stages Copepodite V and female during all cruises. Log10 （x＋l） transformed densities of C. acutus, C. propinquus and M. gerlachei showed positive correlation with temperature and chlorophyll a concentration, while mean population stages of these copopods were negatively correlated with these environmental variables. Younger copepodite stages of C. acutus, C. propinquus and M. gerlachei appeared more often in neritic regions. We confirmed that the polynyas had a great contribution to phytoplankton blooms, which promote copepods reproduction and recruitment success. The study suggested that population dynamics of the four copepods have good correspondence with sea ice and polynya variations during all cruises of the Prydz Bay.
基金The National Key Research and Development Programs of China of the Ministry of Science and Technology under contract Nos 2020YFA0608301,2014CB441503the National Natural Science Foundation of China under contract Nos 41976042,41776122+1 种基金the Fundamental Research Funds for the Central Universitiesthe Taishan Scholars Program of Shandong Province,China。
文摘Quantifying the gross and net production is an essential component of carbon cycling and marine ecosystem studies.Triple oxygen isotope measurements and the O_(2)/Ar ratio are powerful indices in quantifying the gross primary production and net community production of the mixed layer zone,respectively.Although there is a substantial advantage in refining the gas exchange term and water column vertical mixing calibration,application of mixed layer depth history to the gas exchange term and its contribution to reducing indices error are unclear.Therefore,two cruises were conducted in the slope regions of the northern South China Sea in October 2014(autumn)and June 2015(spring).Discrete water samples at Station L07 in the upper 150 m depth were collected for the determination ofδ^(17)0,δ^(18)O,and the O_(2)/Ar ratio of dissolved gases.Gross oxygen production(GOP)was estimated using the triple oxygen isotopes of the dissolved O_(2),and net oxygen production(NOP)was calculated using O_(2)/Ar ratio and O_(2)concentration.The vertical mixing effect in NOP was calibrated via a N_(2)O based approach.GOP for autumn and spring was(169±23)mmol/(m^(2)·d)(by O_(2))and(189±26)mmol/(m^(2)·d)(by O_(2)),respectively.While NOP was 1.5 mmol/(m^(2)·d)(by O_(2))in autumn and 8.2 mmol/(m^(2)·d)(by O_(2))in spring.Application of mixed layer depth history in the gas flux parametrization reduced up to 9.5%error in the GOP and NOP estimations.A comparison with an independent O_(2)budget calculation in the diel observation indicated a26%overestimation in the current GOP,likely due to the vertical mixing effect.Both GOP and NOP in June were higher than those in October.Potential explanations for this include the occurrence of an eddy process in June,which may have exerted a submesoscale upwelling at the sampling station,and also the markedly higher terrestrial impact in June.
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA23050401)。
文摘Herbivore digestion in aquatic ecosystems is usually considered a method of nutrient repackaging rather than recycling,as recalcitrant and low-level nutrients are presumed for their egesta.We hypothesize that this opinion holds only for nutrients recycled by excretion and egestion,not for those elements recycled overwhelmingly by fecal decomposition.In this study,we compared the dissolution of biogenic silica(BSi),phosphorus(P)and iron(Fe)between two food items and fecal pellets of two marine invertebrates fed on artificial seawaters free of bacteria.Relative to raw food materials,the mass proportion in fecal pellets of BSi increased,while that of P and Fe decreased.During the 21 days of incubation,the total dissolution rate of BSi was 13.9–36.0 times higher in fecal pellets than food items,followed by P(1.5–4.2 times)and Fe(1.1–2.4 times).While the dissolution of BSi and Fe occurred mostly in the first few days,P was mostly released in the last ten days.Regarding BSi dissolution,a higher rate was observed in oyster Crassostrea gigas than the Echiuran Urechis unicinctus,but no significant difference was found between fecal pellets in either species under naturally available diatom food(Phaeodactylum tricornutum)and introduced terrestrial food(rice husk powder),respectively.Our results show direct evidence of digestion-associated nutrients mobilization.BSi dissolution after animal digestion may be similarly efficient to that caused by bacteria colonization in natural seawater.
基金supported by the National Natural Science Foundation of China(Grants No. 40821004)the National Key Technology Research and Development Program of China(Grants No.2006BAB18B07)and the China's IPY program
文摘The distribution and abundance of euphausiid larvae and salps was studied from samples collected in 2002 and 2006 from Prydz Bay.Antarctica. Larvae of Thysanoessa macrura and Euphausia superba were mainly distributed in the north of the continental shelf.T.macrura was more abundant and had a relatively wider distribution.In 2006,with ice having retreated and higher seawater temperatures and chlorophyll a levels,E.superba and T.macrura occurred in higher abundances and at more mature developmental stages.Euphausia crystallorophias was mainly distributed in the neritic region.In 2002,with severe ice conditions in the neritic region,abundance of E.crystallorophias was only 95.6 ind·（1000 m）^（-3）.In 2006 when a polynya existed,the abundance of E.crystallorophias reached 43966.6 ind·（1000 m）^（-3）.The population mainly consisted of metanauplius（MN） and calyptopis I（CD.Salps,mostly Salpa thompsoni,had a low abundance in Prydz Bay.In 2002,S.thompsoni was only found at one station in the north of the bay with an abundance of 10 ind·（1000 m）^（-3）.In 2006,S.thompsoni was found at three stations located near the continental slope and average abundance reached 146.7 ind·（1000 m）^（-3）.Environmental factors,such as the timing of ice melt,polynya formation and food concentration appear to have a marked effect on the distribution and abundance of euphausiid larvae and salps.
基金Supported by the Laoshan Laboratory (No.LSKJ202204005)the Mount Tai Scholar Climbing Plan to Song SUNthe Open Fund of CAS Key Laboratory of Marine Ecology and Environmental Sciences,Institute of Oceanology,Chinese Academy of Sciences (No.KLMEES201801)
文摘Ulva prolifera is the causative species of the annually occurring large-scale green tides in China since 2007.Its specific biological features on reproductivity strategies,as well as intra-species genetic diversity,are still largely unknown,especially at the genome level,despite their importance in understanding the formation and outbreak of massive green tides.In the present study,the restriction site-associated DNA genotyping approach(2b-RAD)was adopted to identify the genome-wide single-nucleotide polymorphisms(SNPs)of 54 individual thalli including samples collected from Subei Shoal in 2019 and Qingdao coast from 2019 to 2021.SNPs genotype results revealed that most of the thalli in 2019 and 2020 were haploid gametophytes,while only half of the thalli were gametophytes in 2021,indicating flexibility in the reproductive strategies for the formation of the green tides among different years and the dominance of asexual and vegetative reproductive mode for the floating period.Besides,population analysis was conducted,and it revealed a very low genetic diversity among samples from Subei Shoal and the Qingdao coast in the same year and a higher divergence among samples in different years.The results showed the efficiency of 2b-RAD in the exploration of SNPs in U.prolifera and provided the first genome-wide scale evidence for the origin of the large-scale green tides on the Qingdao coast.This study improved our understanding of the reproductive strategy and genetic diversity of the green tide causative species and will help further reveal the biological causes of the green tide in China.
基金Supported by the Laoshan Laboratory(Nos.LSKJ 202203700,LSKJ 202203704,LSKJ 202204005)the National Natural Science Foundation of China(NSFC)(Nos.42076166,42130411)the NSFC Ship Time Sharing Project(No.42149901)。
文摘Meroplankton play a crucial role in both benthic and pelagic ecosystems.Existing quantitative research on estimating the quantities of meroplankton groups is both underrepresented and inaccurate.To investigate and evaluate the influence of varying mesh sizes(505 and 160μm)on the sampling efficiency of meroplankton,we conducted an examination using two commonly used plankton nets during the spring season in the Southern Yellow Sea(SYS).Our study revealed a total of 12 meroplankton groups,with 9 groups identified in the 505-μm mesh nets and 11 groups in the 160-μm mesh nets.The results demonstrated the superior collection efficiency of the 160-μm net compared to the 505-μm net across the majority of meroplankton groups.Furthermore,we focused on exploring the abundance,distribution patterns,and realized niches of meroplankton collected by the two mesh size nets,and observed that the distribution of meroplankton closely resembled the distribution of possible benthic adults in the SYS.Correlation analysis of the six dominant groups collected in the 160-μm mesh nets revealed that seawater temperature and salinity emerged as the key environmental factors driving variations in meroplankton abundance within the SYS.This study also found that a smaller mesh size net does not necessarily capture meroplankton more comprehensively.A comprehensive understanding of the ecological characteristics of meroplankton requires the combination of two types of nets for research.Our research significantly advances our understanding of the quantification,abundance,and distribution of meroplankton,serving as a valuable contribution to the broader landscape of detailed quantitative meroplankton studies.
基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA19060203)the National Natural Science Foundation of China(Nos.42076166,42130411)+4 种基金the Natural Science Foundation of Shandong Province(No.ZR2021QD061)the CAS-CSIRO Project Fund(No.GJHZ1888)the Mount Tai Scholar Climbing Plan to Song SUNthe Innovation Team of Fishery Resources and Ecology in the Yellow Sea and Bohai Sea(No.2020TD01)the Hainan Province Basic and Applied Basic Research Program(Natural Science Field)High-Level Talent Project(No.2019RC353)。
文摘Cyanea nozakii,a common jellyfish distributed in offshore China,has a complex trophic relationship with other zooplankton groups.However,few studies have reported the predation rates and prey selection patterns of C.nozakii medusae on different prey items.Research is also lacking on the intraguild predation of Aurelia coerulea(another common bloom jellyfish in offshore China)by C.nozakii.To address the knowledge gaps,the clearance rates of C.nozakii for different prey items,including copepods(small<1000μm and large>1000μm),fish larvae,and gelatinous prey(hydromedusae,A.coerulea ephyrae,and chaetognaths),were measured.The influence of predator size on the clearance rate was also determined.Additionally,we examined the intraguild predation of C.nozakii on A.coerulea medusae.The clearance rates of C.nozakii varied widely with prey organisms,being independent of prey concentrations.Gelatinous organisms,except for chaetognaths,were captured with considerably high efficiency,followed by fish larvae and copepods,indicating the preferential prey selection of gelatinous organisms by C.nozakii.The clearance rate increased linearly with the cross-sectional area of C.nozakii.Body size in medusae may,to some extents,underpin their capacity to capture more prey by increasing the encounter rate and capture success through ontogeny.C.nozakii preyed voraciously on A.coerulea in high feeding efficiency,but the clearance rate decreased with increasing A.coerulea(as prey)size.This phenomenon of intraguild predation suggests a speculative hypothesis of potential population regulation of A.coerulea by C.nozakii.The information regarding the feeding ecology of C.nozakii reported in this study is important for understanding plankton dynamics in marine ecosystems with extensive occurrences of this jellyfish.
基金the International Science Partnership Program of the Chinese Academy of Sciences(No.133137KYSB20200002)the Laoshan Laboratory(No.LSKJ202204005)+3 种基金the State Key Program of National Natural Science of China(No.42130411)the International Science Partnership Program of the Chinese Academy of Sciences(No.121311KYSB20190029)the Aoshan Science and Technology Innovation Program(No.2016ASKJ02-4)the Taishan Scholars Project(to Song SUN)。
文摘The Yellow Sea(YS)and East China Sea(ECS)are highly dynamic marginal seas of the northwestern Pacific Ocean.To gain an in-depth understanding of zooplankton community structure,zooplankton abundance,biovolume,and size structure in summer 2017 in the YS and ECS were assessed using ZooScan imaging analysis.Zooplankton abundance and biovolume ranged 2.94–1187.14 inds./m^(3)and 3.13–3438.51 mm^(3)/m^(3),respectively.Based on the biovolume data of the categorized size classes of 26 identified taxonomic groups,the zooplankton community was classified into five groups,and each group was coupled with distinctive oceanographic features.Under the influence of the Yellow Sea Cold Water Mass,the Yellow Sea offshore group featured the lowest bottom temperature(10.84±3.42℃)and the most abundant Calanoids(mainly in the 2–3 mm size class).In the Yellow Sea inshore group,Hydrozoans showed the largest biovolume and dominated in the 3–4-mm and>5-mm size classes.The East China Sea offshore group,which was affected by the Kuroshio Branch Current,featured high temperature and salinity,and the lowest bottom dissolved oxygen(2.58±0.5 mg/L).The lowest values of zooplankton abundance and biovolume in the East China Sea offshore group might be attributed to the bottom dissolved oxygen contents.The East China Sea inshore group,which was mainly influenced by the Zhejiang-Fujian Coastal Current and Changjiang Diluted Water,was characterized by high chlorophyll a and the largest biovolume of carnivorous Siphonophores(280.82±303.37 mm^(3)/m^(3)).The Changjiang River estuary offshore group showed the most abundant Cyclopoids,which might be associated with the less turbid water mass in this region.Seawater temperature was considered the most important factor in shaping the size compositions of Calanoids in different groups.
文摘As a National Basic Research Program (973 Program) of China, the Key Processes, Mechanism and Ecological Consequences of Jellyfish Bloom in China Coastal Waters led by Prof. SUN
