Optimal salinity for dominant copepods in the East China Sea, determined using a yield density model

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.

Study on biological oceanography charateristics of planktonic copepods in waters north of Taiwan Ⅱ. Community characteristics

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.

Population dynamics of four dominant copepods in Prydz Bay, Antarctica, during austral summer from 1999 to 2006

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.

Studies of community structure and seasonal dynamics of planktonic copepods in saline-alkaline ponds

Species abundance and seasonal succession of copepods in saline-alkaline ponds were studied in Zhaodian Fish Farm, Gaoqing County, Shandong Province, from 5 April 1997 to 1 September 1998. The results indicated that in the conditions of salinity ranging from 1.36 to 20 g/L, total alkalinity changing from 2.4 to 7.2 mmol/L and pH 8–9, zooplankton in saline-alkaline ponds was composed of freshwater salt-tolerated species or halophile species, some of which are halobiont species and usually occurs in freshwater. In our study, copepods were predominant in many fish-culture ponds and all control ponds without fishes in spring, late autumn and early winter. Dominant species of copepods were Sinocalanus tenellus, Cyclops vicinus, Thermocyclops taiho- kuensis. The biomass of copepods in the control ponds without fishes was higher than that of the fish-culture ponds.

Distribution patterns of appendicularians and copepods and their relationship on the northwest continental shelf of South China Sea during summer

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.

Community structure of planktonic copepods in artificial reefs of Wenchang,Hainan

To understand the characteristics of population structure of planktonic copepods and their response mechanisms to marine environmental factors in different seasons,the community structure of planktonic copepods in samples obtained from 7 stations in artificial reefs of Wenchang,Hainan Province in March and September 2019 were investigated.A total of 33 species of planktonic copepods belonging to 23 genera within 17 families were identified in artificial reefs,with 27 species and 21 genera in spring,and 23 species and 19 genera in fall,respectively.The identified planktonic copepods were further categorized into estuarine groups,warm temperate groups,warm water coastal groups,and warm water widespread groups.The predominant species in spring were mainly composed of Temora turbinata and Canthocalanus pauper,whereas Tortanus gracilis and Subeucalanus subcrassus were dominant species in fall.The species and abundance of planktonic copepods in spring were higher than that in fall,while the diversity index and evenness were vice versa,with obvious seasonal differences.In addition,there was a correlation between the population of copepods and physicochemical environmental factors.The major warm water group of copepods in spring showed different degree of correlation with environmental factors,such as NO2-N,NH3-N,pH,water depth,temperature etc.,while the population of copepods in fall was affected by limiting factors such as dissolved oxygen,pH,and temperature.In conclusion,copepods species inartificial reefs were rich and diverse,and their community structure tended to be stable.In addition,the surrounding water quality was generally good,and the whole marine ecosystem and ecological environment were in good condition.

Copepods in Hypersaline Waters Worldwide:Diversity,Environmental,Social,and Economic Roles

1 Introduction Copepods are a group of small crustaceans,which play an important ecological role in aquatic ecosystems.They occupy different ecological niches in aquatic food webs,contributes to biogenic element cycles,and transfer of organic matter from primary producers to higher secondary consumers.Copepods also have the potential to

Studies on the chemical composition of some planktonic copepods in the Taiwan Strait

The chemical composition of marine zooplankton was studied though two seasonal cruises (August 1994and February 1995) in the Taiwan Strait. The carbon(C), nitrogen(N) and hydrogen(H) dry weight contents ofplanktonic copepods were in the range of 36. 24% -45. 63%,8 .50% -11. 37% and 4. 23%-6. 50% repectively.Data comparison among the three southern sea areas of China showed the same subtropical characteristics in the chemical composition of planktonic crustaceans. The seasonal changes of C and N contents and C/N ratio in the TaiwanStrait implied the different nutritional conditions in the open sea from those in the inner gulf.

Distribution of planktonic copepods in the Kuroshio area of the East Chine Sea to the southwest of Kyushu in Japan

The materials were obtained from the survey conducted in the Kuroshio area of the East China Sea to the Southwest of Kyushu in Japan (29°30'-32°00', 128°00'-130°'00'E) on board the R. V. Yoko Maru of Seikai Regional Fisheries Lab, Fisheries Agency, Japan in June 15~28, 1988 during China-Japan Joint Research on the Kuroshio. Zoo-plankton was collected by means of the North Pacific Net with model TSK flowmeter through vertical haul from 50 -Om. Temperature and salinity were measured with CTD. 134 species (including 4 spp. ) of planktonic copepods were preliminarily identified in the survey area. Most of them belonged to the tropical and subtropical species and a few of them were the warm-temperate species and eurytopic species. The main dominant species vteieOncaea venusta, Oithona plumifera, Clausocalanus furcatus, C. Arcuicornis, Paracaianus dculeatus, Oithona similis, Temara turbinata, Oncaea media, Undinula danvinii, Acartia negligent, Corycaeus speciosus, Scolecithrix danae, etc. The total number of individuals of planktonic copepods were about 367. 6 ind. /m3 on an average. The horizontal distribution of planktonic cope-pods was less in number but more in species in the main current area of the Kuroshio. The variations of growth and decline of the warm Kuroshio and the coastal current along China coast influenced the community structure and the distribution of planktonic copepods. Water temperature was one of principal controlling factors affecting the species composition and the quantitative distribution of planktonic copepods.

Carbon biomass,production rates and export flux of copepods fecal pellets in the Changjiang(Yangtze) River estuary

Copepod fecal pellets are ubiquitous throughout the oceans. Their production and export can represent a highly efficient pathway of carbon export. However, the role these fecal pellets play in carbon export in the Changjiang(Yangtze) River estuary is not well known. Two cruises were carried out in the Changjiang estuary in the spring and summer of 2013, during which time carbon biomass, production, and export of copepod fecal pellets were studied. Spring and summer fecal pellet carbon biomass ranged 0.30–1.01 mg C/m^3(mean=0.56±0.20 mg C/m^3) and 0.31–1.18 mg C/m^3(mean=0.64±0.24 mg C/m^3), respectively, significantly lower than phytoplankton. At most stations, fecal pellet carbon biomass was higher in surface or subsurface layers than deeper layers. Production rates ranged 0.65–1.49 pellets/(ind.?h)(mean=1.02±0.27 pellets/(ind.?h)) in spring and 0.62–1.34 pellets/(ind.?h)(mean=0.98±0.22 pellets/(ind.?h)) in summer, within the range reported in previous studies. Higher production rates of fecal pellets occurred at stations with higher chlorophyll a concentrations, and production rates of copepods of size 500–1 000 μm greater than copepods >1 000 μm during both cruises. The potential export flux of fecal pellets was slightly higher in summer(mean=68.95±14.37 mg C/(m^2 ?d)) than spring(mean=52.08±11.33 mg C/(m^2 ?d)) owing to higher summer copepod abundances. To our knowledge, this study is the first of its kind in the Changjiang estuary, and it confirms the significant role of copepod fecal pellets in local carbon export.

Effects of UV radiation on the RNA/DNA ratio of Copepods from Antarctica and Chile

The effect of ultraviolet （UV） radiation on marine organisms has been an important focus of recent research, with depletion of the ozone layer resulting in increased UV radiation at high latitudes. Several studies have identified negative impacts of UV radiation on the biology of zooplanktonic organisms. This study used the RNA/DNA ratio as a measure of stress in copepod assemblages from Fildes Bay in Antarctica and Quintay Bay on the central coast of Chile, two areas with high UV radiation but different photobiologic histories. Controlled time-light experiments were performed with copepods from the two locations, exposing them to white light, UV light, or darkness. The results showed different responses to UV radiation. Copepods from Fildes Bay showed a slow metabolic response to UV radiation after 4 and 8 h of exposure. Copepods from Quintay Bay showed a fast metabolic response after 4 h of exposure （4 orders of magnitude higher than that for Fildes Bay copepods） followed by a rapid return toward baseline after 8 h of exposure. These different responses probably reflect the time the eopepod assemblages have been exposed to increased UV radiation and the extent of adaptive stress responses to cope with that increased UV radiation. The results of this study show that the RNA/DNA ratio is a useful indicator of the physiologic status of marine organisms and is a useful tool to measure the effects of changing environmental conditions on marine ecosystems, such as those associated with global climate change.

Diversity and Abundance of Copepods in Taninthayi Coastal Waters, Myanmar

Diversity and abundance of copepods occurring in Taninthayi coastal waters were studied and analyzed from the samples collected by R/V DR.FRIDTJOF NANSEN during the Myanmar ecosystem survey 2018.Seventy-nine copepods species belonging to calanoids(51 species),cyclopoids(21 species),and harpacticoids(7 species)were identified in the copepods community of Taninthayi coastal waters.Copepods species number and density were high at the nearshore stations(Sts 799,842,788)and low at the offshore stations(Sts 846,802,823).The resulted diversity index values of copepods were varied from 2.61 to 3.78 in species diversity index(H'),from 0.89 to 0.97 in the evenness index(E'),and from 2.51 to 7.50 in species richness index(D').According to the correlation matrix,the abundance of copepods was positively correlated with temperature,chlorophyll a and fluorescence,and negatively correlated with salinity and oxygen.

Parasitic Copepods on Common Carp(Cyprinus carpio,L.1758)from Gradche Reservoir(Macedonia)

During the parasitological examinations of the common carp(Cyprinus carpio,L.1758)from the Gradche Reservoir(Macedonia),a total of 126 fish samples were examined,from which parasite infestation was determined in 87 fish(69.05%).In this research,the following parasitic copepods were identified:Ergasilus sieboldi,Ergasilus briani,and Lernaea cyprinacea.Ergasilus sieboldi was found on gills of common carp,with a prevalence of 1.461%,while the mean intensity was 2.357.Ergasilus briani was found on fins of common carp,with a prevalence of 1.879%,while the mean intensity was 38.274.Lernaea cyprinacea was found on the fins of common carp,with a prevalence of 0.552%,while mean intensity was 2,000.Our findings of Ergasilus sieboldi,Ergasilus briani,and Lernaea cyprinacea in common carp are considered as first records for Macedonia.At the same time,common carp is a new host for Ergasilus briani in Macedonian waters.

Impacts of CO_2-driven seawater acidification on survival,egg production rate and hatching success of four marine copepods

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.

Seasonal variation in community structure and body length of dominant copepods around artificial reefs in Xiaoshi Island,China

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.

Seasonal change in body length of important small copepods and relationship with environmental factors in Jiaozhou Bay, China

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.

Preliminary study of the retention mechanism of planktonic copepods in the Jiulong Estuary in China

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.

Characterization and analysis of ribosomal proteins in two marine calanoid copepods

Copepods are among the most abundant and successful metazoans in the marine ecosystem. However, genomic resources related to fundamental cellular processes are still limited in this particular group of crustaceans. Ribosomal proteins are the building blocks of ribosomes, the primary site for protein synthesis. In this study, we characterized and analyzed the c DNAs of cytoplasmic ribosomal proteins(c RPs) of two calanoid copepods, P seudodiaptomus poplesia and A cartia pacifi ca. We obtained 79 c RP c DNAs from P. poplesia and 67 from A. pacifi ca by c DNA library construction/sequencing and rapid amplifi cation of c DNA ends. Analysis of the nucleic acid composition showed that the copepod c RP-encoding genes had higher GC content in the protein-coding regions(CDSs) than in the untranslated regions(UTRs), and single nucleotide repeats(>3 repeats) were common, with "A" repeats being the most frequent, especially in the CDSs. The 3′-UTRs of the c RP genes were signifi cantly longer than the 5′-UTRs. Codon usage analysis showed that the third positions of the codons were dominated by C or G. The deduced amino acid sequences of the c RPs contained high proportions of positively charged residues and had high p I values. This is the fi rst report of a complete set of c RP-encoding genes from copepods. Our results shed light on the characteristics of c RPs in copepods, and provide fundamental data for further studies of protein synthesis in copepods. The copepod c RP information revealed in this study indicates that additional comparisons and analysis should be performed on different taxonomic categories such as orders and families.

Spatial and Temporal Variations of Pelagic Copepods in the North Yellow Sea

This study aims to analyze the spatial and temporal variations of the abundance and biodiversity of pelagic copepods and their relationships with the environmental factors in the North Yellow Sea(NYS). These variations were analyzed on the basis of the survey data of the NYS in four seasons from 2006 to 2007. A total of 31 copepod species that belong to 17 genera, 13 families and 4 orders were identified in the four seasons. Of these copepods, the species belonging to Calanoida is the most abundant component. The dominant species include Calanus sinicus, Centropages abdominalis, Paracalanus parvus, Acartia bifilosa, Oithona plumifera, and Corycaeus affinis. C. sinicus is the most important and widely distributed dominant species in all of the seasons. The dominant species have not shown any significant variation for the past 50 years. However, the richness of warm-water species increased. The abundance of copepods significantly varied among different seasons: the average abundance was higher in spring(608.2 ind m^(-3)) and summer(385.1 ind m^(-3)) than in winter(186.5 ind m^(-3)) and autumn(128.0 ind m^(-3)). Factor analyses showed a high correlation between the spatial distributions of dominant copepods and environmental parameters, and Chl-a was the most important factor that influenced the distribution of copepods. This research can provide the fundamental information related to zooplankton, especially pelagic copepods. This research is also beneficial for the long-term monitoring of zooplankton ecology in the NYS.

Dietary separation between co-occurring copepods in a food-limited tropical coral reef of the Sanya Bay

Food differentiation among coexistent species in the field is important strategy for copepods to acquire materials and maintain population stabilization.In situ diet analysis of co-occurring six copepod species in coral waters of the Sanya Bay was conducted using a PCR protocol based on 18 S ribosomal gene.Various prey organisms were uncovered,including dinoflagellate,diatom,green algae and plant,protozoa and metazoan.All these spatially coexisting six species showed different dietary diversity,with the food niche breadth(B)ranging from 1.00(Temora turbinate in morning)to 10.68(Calanopia elliptica in night).While food overlap between all these copepods were low,with the average value of the diet niche overlap index being approximately 0.09.Even temporally co-existing species sampled from the same time point fed on different groups of prey items with the food overlap index of 0.04 to 0.07 in midday and night but 0 in morning.As the most important dominant copepod in the Sanya Bay,Subeucalanus subcrassus seems to be capable to regulate its feeding,by exhibiting a rhythm of herbivorous feeding in midday and carnivorous feeding in morning and night,to better coordinate with other competitors for utilization of food resources.For most copepods,none of the prey items belonged to the dominant phytoplankton in the ambient water,indicating that copepod can better their survival by widening the choice of potential food resources in food limited environment.The dietary separation observed here might be important strategy for copepod to maintain population stabilization and thriving in the Sanya coastal waters.