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The shallow hydrothermal vents (HVs) of Kueishan Island are considered as a template for studying the extremes of sulfide-polluted and acidified water. The present study examined the biological and spatiotemporal aspects of mesozooplankton mortality in waters around this extreme HV environment. Zooplankton sample collection was carried out in three monsoonal periods and the results revealed that there was a significant decrease in the mortality of total mesozooplankton with increasing distance from the HVs. The overall mortality of mesozooplankton showed a significant negative correlation with sea surface temperature and pH. Particularly, mortality of copepods showed a significant negative correlation with pH, whereas it was significantly positive correlated with sea surface temperature in the southwest monsoon prevailing period. Overall, the results may imply a situation that zooplankton will encounter in the more acidified environment of a future ocean. • Hydrothermal vents exert different mortalities on different mesozooplankton taxa. • Low pH significantly increases mesozooplankton mortality. • Lethal mesozooplankton effects decrease with increasing distance from hydrothermal vents. • Mesozooplankton mortalities differ with monsoonal periods. [ABSTRACT FROM AUTHOR]

Abstract The environmental impact caused by thermal discharge waters of power plants is of global concern since thermal discharge directly affects the environmental situation near power plants. The present study used the vital stain neutral red to identify live and dead zooplankton collected from stations at the intake and the outlet of two nuclear power plants (NPPs). Significantly higher mortalities occurred at the outlet station than at the intake station (p < 0.01) at both NPPs. The mortalities of most zooplankton taxa and all zooplankton assemblages were significantly positive correlated to differences of water temperature (ΔT) at NPP I (p < 0.05), whereas it was not significantly positive correlated with ΔT at NPP II (p > 0.05). The weight of organic matter of zooplankton fragments was higher at the outlet station than at the intake station at both NPPs, indicating the physical damage of zooplankton when passing the cooling system. Highlights • The cooling system of nuclear power plants cause zooplankton mortality. • Environmental differences between nuclear power plants affect zooplankton mortality. • Cooling water and mechanical damage are affecting zooplankton mortality. [ABSTRACT FROM AUTHOR]

Coral symbiotic crabs provide considerable benefits to their host corals. A comprehensive understanding of the association between these crabs and their hosts could help clarify the relationship, interaction, and importance of symbionts with coral reefs as hosts. In this study, the coral symbiotic crab Tetralia rubridactyla was test for host preference and fidelity. Five oceanic objects were provided to the crabs: common host corals ( Acropora hyacinthus and A. digitifera ), uncommon host corals ( Pocillopora damicornis and Stylophora pistillata ), and dead coral skeletons. The crabs were collected from the 2 source host corals A. hyacinthus and A. digitifera and subjected to an experiment comprising 7 treatments. Each treatment included 2 stages of no-choice and choice conditions to estimate the expected selection frequencies. The results revealed that the crabs chose any available object under the no-choice condition, and exhibited various preferences under the choice condition. Moreover, T. rubridactyla exhibited significantly higher frequencies to inhabit Acropora corals ( p < 0.01, χ 2 test), than dead coral skeletons and uncommon host corals. In all the treatments, the preferences of the crabs from the 2 source hosts were similar. Present results demonstrated T. rubridactyla host selection conditioning as follows: (1) Under the no-choice condition, inhabit any choice object for shelter; (2) under the choice condition, if without a common host, randomly inhabit any uncommon choice object as a host; and (3) under the choice condition, if a common host is available, selecting the common host is the first priority because it could provide food and space. This study revealed that T. rubridactyla express neither fidelity nor preference between A. hyacinthus and A. digitifera . Thus, these results also suggested that the distribution of T. rubridactyla on Acropora corals in the reef is affected by an abundance of corals rather than the preferences of coral species. [ABSTRACT FROM AUTHOR]

[Display omitted] The rising demand of ecosystem services, due to the increasing human population in coastal areas, and the subsequent need to secure healthy and sustainable seas constitute a major challenge for marine ecosystems management. In addition, global anthropogenic changes have transformed the marine realm, thereby challenging ecosystem health and the services necessary for human welfare. These changes have opened ecological space for opportunistic organisms, such as jellyfish, resulting in ecosystem-wide and economic implications that threaten marine ecosystem services. Here, we used a comprehensive dataset of jellyfish hazards over the period 1960–2019 to track their dynamics and implications for human welfare. Our results revealed that their large-scale patterns have been mainly enhanced in human-perturbed Large Marine Ecosystems, although the contribution of jellyfish Class to hazard type changed across ocean regions. The long-term variability of these events suggests that their temporal patterns mirror the pace of ocean warming and ocean health degradation nurtured by global anthropogenic changes in recent decades. These results warn of the wide socioecological risks of jellyfish hazards, and their implications advocate for transboundary, regional cooperation to develop effective ecosystem-based management actions. Failure to integrate jellyfish into ocean surveys will compromise coastal ecosystem services governance. Classification: Social Sciences/Sustainability Science, Biological Sciences/Ecology. [ABSTRACT FROM AUTHOR]

The influence of Kuroshio water on temporal distribution and copepod diversity was investigated in the Lanyang River estuary (LRE), the longest river in northeast Taiwan, to assess secondary productivity. Zooplankton samples were collected bimonthly from the surface waters (0–2 m) of the estuary during cruises in 2006. Hydrological parameters indicated that the water in the LRE was an admixture of the Lanyang River water and seawater. Among the different genera, 47 copepod species (including 10 species that were identified only to the generic level) belonging to 28 genera, 16 families, and 4 orders were identified. The abundance and proportion of copepods to the total zooplankton counts range from 0 to 3683.42 (304.9±692.7 individuals m −3 ) and from 0 to 100 (55.09±34.84%) respectively. The copepod community structure revealed a distinct seasonal succession and showed significant differences among the sampling cruises ( p <0.05, One-way ANOVA). The 5 most abundant species were Parvocalanus crassirostris (relative abundance [RA]: 50.93%), Pseudodiaptomus serricaudatus (RA: 16.85%), Euterpina acutifrons (RA: 7.34%), Cyclops vicinus (RA: 4.82%), and Microcyclops tricolor (RA: 3.15%). The abundance, species number, indices of richness, evenness, and copepod diversity varied significantly ( p <0.05, One-way ANOVA) for all the cruises. Pearson correlation analysis results demonstrated that salinity was positively correlated with the copepod species number (r=0.637), total copepod abundance (r=0.456), and Shannon–Wiener diversity index (r=0.375) with a 1% level of significance. By contrast, the evenness index was negatively correlated with salinity (r=−0.375, p =0.01), indicating that copepod diversity in the LRE was influenced mainly by seawater. The Kuroshio Current played a major role in transporting and distributing warm-water copepods to its affected area. Copepod species assemblages showed seasonal succession and varied drastically with tidal change. The latter registered high abundance, and the presence of the highest number of species was correlated with intruding seawater. [ABSTRACT FROM AUTHOR]

Zooplankton communities are affected by spatial and temporal factors, as well as by general weather conditions, monsoons, and ocean currents. Present study examined the effects of typhoons, monsoons, and interplay waters on jellyfish assemblages in the complex hydrosystem in the coastal areas of the southern East China Sea. The species and composition of jellyfish and their seasonal succession in the coastal areas of northern Taiwan were investigated through 6 research cruises between October 2007 and January 2009. Among the samples obtained during these cruises, 23 jellyfish species from 2 classes, 7 orders, 13 families, and 19 genera were identified. The 3 most abundant jellyfish species were Nausithoe punctata (relative abundance, RA: 91.72%), Aglaura hemistoma (RA: 4.20%), and Diphyes chamissonis (RA: 1.13%). The species A. hemistoma exhibited the highest occurrence ratio (OR, 52.78%), and only this species was observed during all 6 research cruises. The abundance of Corymorpha bigelowi and Lensia multicristata correlated significantly and positively with seawater temperature, indicating that these species are brought to northeastern Taiwan by the warm Kuroshio Current. The formation of an N. punctata bloom yielded a density of 543.25 individuals/m −3 in October 2008, indicating that the jellyfish assemblage was influenced by a typhoon event and exhibited a clear pattern of seasonal succession. However, the interplay waters of the China Coastal Current and Kuroshio Current had a greater influence in shaping the jellyfish assemblage structure than did either typhoons or monsoons. [ABSTRACT FROM AUTHOR]

Abundance and productivity of smaller copepods such as the cyclopoid Oithona spp. have been substantially underestimated in most studies, primarily due to large mesh sizes employed during zooplankton tows. Several studies demonstrate that the assemblage structure of Oithona spp. shows considerable variation at temporal and spatial scales. We report here the remarkable horizontal variation in distribution as well as abundance patterns of 8 Oithona species off northeastern Taiwan in the southeastern East China Sea and compare this distribution pattern with community compositions worldwide. The present study provided the first explanation of a spatial distribution pattern and a relationship between species richness and area, as well as community similarities with increasing distance worldwide for the ecologically important planktonic copepod genus Oithona . [ABSTRACT FROM AUTHOR]

Mesozooplankton (Body size 20–200 μm) along with the surface water were collected from coastal regions of Sundarban, northeastern part of Bay of Bengal considering three seasons, namely premonsoon, monsoon and postmonsoon. Samples were analyzed for community structure and the dominant copepod species were further analyzed for trace metal concentration. In total, 50 copepods were identified (22 families and 43 genera). The dominant mesozooplankton species included 9 copepods and an epipelagic chaetognath, exhibited both spatial and seasonal variations. Metal concentration exhibited considerable inter-specific variations for the copepods and the mean concentrations were: Fe, 1350.2–51118.3 μg/g; Al, 647.2–73019.1 μg/g; Ni, 32.4–110.3 μg/g; Mn, 122.8–1066.5 μg/g; Pb, 0.04–97.5 μg/g; Pb, 10.6–97.5 μg/g; Cd, 4.2–21.6 μg/g; Cu, 17.4–145.1 μg/g; Zn, 225.7–1670.9 μg/g; Cr, 21.7–194.3 μg/g; Co, 1.32–111.1 μg/g. Metal concentrations showed the following order: Sagitta bedoti > Coryceas danae > Oithona sp. > Eucalanus subcrassus > Labidocera euchaeta > Paracalanus parvus > Acartiella tortaniformis > Acartia spinicauda > Pseudocalanus serricaudatus . [ABSTRACT FROM AUTHOR]

Abstract: Although mesozooplankton are important components of aquatic food webs and biogeochemical cycling, this plankton fraction is inadequately described and quantified. Standardized sampling procedures for its worldwide characterization are lacking as yet, affecting meaningful comparisons between regional situations. Mesh sizes in use vary greatly among studies, raising the possibility that sampling method bias results for size-related phenomena of the plankton, such as abundance and diversity in space and time. We tested the effects of different mesh sizes for sampling on the resulting size-frequency distributions of mesozooplankton by collecting copepod assemblages in the northern South China Sea. Sample retrieval by different mesh-size plankton nets were compared, using the abundance and distribution patterns of mesozooplankton collected with NORPAC zooplankton nets of 333, 200, and 100-μm mesh size. One-way ANOVA results for species number and richness indices of all samples showed significant differences between these three mesh size nets. In contrast, total copepod abundance of the 100-μm net was significantly higher than that from the 200-μm net (p =0.001) and of the 333-μm net (p <0.001). Index values of evenness and diversity were significantly different among the copepod assemblages obtained from the three mesh size nets. The evenness index values of the 100-μm net were significantly lower than those recorded from the 200-μm net (p =0.007) and the 333-μm net (p <0.001). The Shannon–Wiener diversity index of the 333-μm net was significantly higher than for the 200-μm net (p =0.016) and for the 100-μm net (p =0.006). In addition, the dominant species proportion in each copepod assemblage obtained in the three mesh size nets differed significantly. Densities of smaller mesozooplanktons such as copepodites were highly underestimated by larger meshed nets that were commonly used in previous studies in the waters of the North Pacific Ocean. Samples collected with a 100-μm mesh net demonstrated the numerical importance of smaller mesozooplankton in the northern South China Sea. Present results, therefore, suggest a striking selectivity of plankton net mesh sizes that significantly affected qualitative and quantitative aspects of copepod assemblages. [Copyright &y& Elsevier]

Abstract: We analyse the influence of the Kuroshio Current on copepod assemblages in the northern South China Sea. The assumption was tested whether predominant current regimes bring marine zooplankton and Copepoda from subtropical and tropical waters to the south of Taiwan. A total of 101 copepod species were identified from 26 families and 48 genera that include Calanoida, Cyclopoida, Harpacticoida and Poecilostomatoida. High copepod abundances in the study area are shown to be caused by both, a year-round Kuroshio Current intrusion and the SW monsoon, prevailing in the South China Sea during summer. Calanus sinicus did not appear in the samples, indicating that there was no cold water mass intrusion in the area during sampling. Both, the intrusion of the Kuroshio Branch Current to the Luzon Strait and the South China Sea circulation may play a more important role in shaping copepod assemblages in the region than hitherto expected. The abundance of copepods was higher above the 50 m isoline than at deeper strata. Species number and the Shannon–Wiener diversity index were higher with increasing depth. Copepod assemblage structure changed with different sampling depth and different sampling areas. Copepod abundance and species richness were higher in the northern South China Sea than in the Kuroshio Current area, and higher at lower latitudes than at higher latitudes. Some indicator species are characteristic for the Kuroshio Current and indicate with others that the study area accomodated water masses from the northern South China Sea as well as from the Kuroshio Current. [Copyright &y& Elsevier]

The euryhaline calanoid copepod Pseudodiaptomus annandalei perennially occurs in tropical and subtropical brackish water ecosystems and harbors supporting harmful algal blooms. In the present paper we provide a quantitative assessment of the influence of the diatom-derived poly-unsaturated aldehyde (PUA), 2- trans -4- trans -decadienal on demographic traits of P. annandalei . The survival and reproduction of P. annandalei were recorded in life table experiments, using a cohort of adult males and females exposed to a range of concentrations (0.75, 1.5, 3 and 4.5 μM) of decadienal. Higher mortality of female cohorts and lower reproduction were recorded with increasing concentrations of decadienal (3 and 4.5 μM). The estimated survival time for cohort females (control: 9.7 days; 4.5 μM decadienal: 4.7 days) and developmental stages of copepods (control: 10.5 days; 4.5 μM decadienal: 1.0 days) in decadienal applied medium ( Isochrysis galbana + decadienal) was significantly lower than those in control (only I. galbana ). Detrimental effects further eroded recruitment by increasing naupliar mortality and impairing copepodite development to adulthood. Since P. annandalei is widely used in the aquaculture industry in Asia, the present results call for a limited use of PUA producing diatoms as algal food to avoid impairing copepod reproduction and development. [ABSTRACT FROM AUTHOR]

Spatial and temporal distribution of community structure and seasonal distribution of mesozooplankton (MZ; 20–200 μm) in the context of environmental parameters were studied in the coastal waters of Indian Sundarban wetland formed at the confluence of Hugli (Ganges) River estuary, India. The work has been aimed for better understanding of its ecological characteristics in terms of the most dominant mesozooplankton group in a tropical mesomacrotidal setting. Samples were collected from four sampling sites of different hydrodynamic set up using a ring trawl net (Hydro-Bios No. 438 700, mesh size 200 μm) equipped with a calibrated flowmeter and both water and plankton samples were analyzed by standard methods. Distribution of MZ showed bimodality with two peak periods, primary peak during April coinciding with maximum number of copepod species (974 ind. m − 3 ) and the secondary one during August. Copepod was the most dominant taxon where the calanoids formed bulk of the biomass representing 33 species of 7 genera, while cyclopoids formed the next dominant group comprising 4 species of 3 genera followed by 4 monogeneric harpacticoid species. Results of correlation matrix revealed that two copepod families Acartiidae and Pseudodiaptomidae maintain negative relationship with other six families indicating that they form a group by themselves. Results of multiple regression analysis reveal that salinity, chlorophyll -a and transparency are the potential hydrological factors in the distribution and existence of the dominant copepods and total chaetognaths. An overall high diversity index values (max. 3.21) was associated with high richness index (4.39) and high evenness index (0.96) at the site of the mouth of the estuary. In terms of feeding guild, the herbivore copepods were dominant followed by omnivores. Cluster analysis confirmed an overall dominance of the calanoid copepod Bestiolina similis as a solitary group for all the sites. The chaetognath Sagitta bedoti was perennial in distribution where the contribution of juvenile form (recognized as Stage I ) was dominant. Among the other MZ, hydromedusae, ctenophore, sergestid and mysid were also encountered contributing insignificant part of the total density. A long-term decadal change in copepod community was pronounced which might be due to climate-induced environmental changes which also modulate the physicochemical characteristics of water. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the influence of permanent oceanographic features in structuring copepod assemblages in the northern South China Sea during the inter-monsoon transition periods, spring and autumn. A total of 25 families, 48 genera and 88 species, were recorded, as well as a decrease in species richness along with the seasonal temperature decrease. We show that copepod assemblages are influenced by quasi-permanent oceanographic conditions governing the Northeastern South China Sea, i.e. China Coastal Current and the Kuroshio Current intrusion. This study provides a synoptic picture of the seasonal changes in the community structure of copepods during spring and autumn in the northern South China Sea. [Copyright &y& Elsevier]