Zooplankton Structure Research Articles

The Planktonic Rotifer Community in a Lake Restored with Selective Hypolimnetic Withdrawal

The objective of this study was to analyze variations in the planktonic rotifer community in a lake subjected to hypolimnetic withdrawal. The present study is also the first attempt to estimate the effects of changes in hypolimnion water withdrawal rates on the zooplankton community. The lake is located in northeastern Poland. Zooplankton were sampled in 1986, 2004 and 2013. Standard protocols of zooplankton sampling and elaboration were applied. Rotifer abundance, wet biomass, community structure, and species diversity were studied at different intensities of hypolimnetic water withdrawal. Trophic state indices based on rotifer abundance and species structure were used to evaluate changes in the trophic state of the lake. Our results showed increased planktonic rotifer species diversity over a period of years, which was a positive outcome of the restoration measures. Lower hypolimnetic withdrawal rates seemed to favor the development of a diverse rotifer community. Conversely, qualitative changes in zooplankton structure and a zooplankton-based assessment of the lake trophic state indicated that water eutrophication was progressing. Despite modifications to the operation of the pipeline, no significant differences in rotifer abundance or biomass were detected between the sites in each year or among years at each site.

Comprehensive Insight into Lake Nasser Environment: Water Quality and Biotic Communities—A Case Study before Operating the Renaissance Dam

This study focused on the monitoring and assessment of aquatic ecosystem functioning based on the abiotic and biotic features of Lake Nasser in the post-flood and pre-flood periods as the last ones before water storing behind the Grand Ethiopian Renaissance Dam. The physicochemical parameters, distribution and structure of biotic communities, including bacteria, phytoplankton, zooplankton, macrophytes, epiphytes and fish were analyzed at 15 sites. The values of most parameters (primarily temperature, total suspended solids, pH, orthophosphates, carbonates, sulphates and some cations) were higher in the pre-flood period, whereas higher values of conductivity, total dissolved solids, total solids, nitrites, nitrates, chemical oxygen demand, bicarbonates and chlorophyll a were recorded in the post-flood period. Cyanobacteria-dominated phytoplankton and total coliform bacteria were more abundant in the pre-flood period, and especially at sites 10–15, whereas higher abundances of zooplankton were recorded in the post-flood period. All these changes in parameters were significantly differentiated, and only the concentrations of dissolved oxygen, biochemical oxygen demand, ammonium and silicates were at similar level in both periods. The study also indicated that environmental factors had affected the macrophyte distribution and the adaptation of the invasive species Myriophyllum spicatum to thrive under different environmental factors in the lake. Besides, macrophytes provided the habitat to other aquatic organisms, especially epiphytes, and also helped maintaining the good water quality, nutrient cycling and stabilizing rivers’ and lakes’ banks. Generally, these conditions were rather favorable for biological processes and fish production.

Spatio-temporal Distribution Characteristics and Driving Factors of Zooplankton in Hongze Lake

Hongze Lake is the fourth largest freshwater lake in China and is an important source of water for surrounding industrial and agricultural processes and fishery resources. Analyzing the changes in the zooplankton community structure in Hongze Lake can provide scientific support for the scientific management of its ecology and environment. A one-year monthly monitoring study was conducted from March 2017 to February 2018 to analyze the temporal and spatial changes in species composition, density, and biomass of zooplankton in Hongze Lake, as well as the seasonal changes in community diversity and dominant species. Canonical correspondence analysis was employed to explore the relationships between the temporal and spatial changes in zooplankton and the environmental factors of Hongze Lake. The results showed that the average annual density of zooplankton in Hongze Lake was 383.87 ind ·L-1, and the average annual biomass was 1.36 mg ·L-1. The community structure of zooplankton in Hongze Lake varied greatly across time and space. Community structure varied greatly in summer, and zooplankton density and biomass reached a maximum in autumn. The community structure of the zooplankton was the simplest in winter. Chengzi Bay and Lihewa Bay exhibited an abundance of many different zooplankton species with limited spatial differentiation, whereas the zooplankton in the overflow area comprised fewer species but exhibited greater spatial variation. In summer, water level and temperature are the dominant factors, whereas in autumn and winter, the dominant factors are water temperature, nutrients, and chlorophyll. Canonical correspondence analysis showed that the temporal and spatial changes in zooplankton community structure in Hongze Lake were mainly determined by water level, total phosphorus, water temperature, and total nitrogen content. Water level fluctuation has the greatest direct impact on zooplankton community structure, and water quality regulation has indirect impact.

Features of the formation of zooplankton of the upper Ob in the conditions of the influence of the megapolis

Journal: Рыбоводство и рыбное хозяйство №8 2021, №8, 2021 Based on the data obtained in the study of some hydrobiological sections of the Ob River, located above and below the city. The qualitative and quantitative characteristics of the zooplankton community were considered, and the saprobity index was calculated. The species composition is represented by 34 species from three systematic groups, of which 12 are rotifers (Rotifera), 14 are branchial crustaceans (Cladocera), and 10 are copepods (Copepoda). The highest species diversity was observed above the city — 34 taxa, the lowest below the city — 14. The average number of zooplankton above the city of Novosibirsk is insignificant and reached 761 copies/m³ per year. Most (49%) were copepods (Copepoda). The number of rotifers (Rotifera) was 34% of the total. In the summer, the number of zooplankton was slightly higher than the annual one and amounted to 871 copies/m³. The average annual biomass of zooplankton had low values and was 35.0 mg/m³. The maximum summer values reached 180 mg/m³. In the study area of the Ob River below Novosibirsk, the average number of zooplankton increases to 2,4 thousand copies/m³. The group of oar-footed crustaceans dominated in number, its share reached 91%. The number of branchiform crustaceans was 7%. The average annual zooplankton biomass in the river below the city limits was 99.53 mg/m³. The value of the saprobity index in the area above Novosibirsk was 1.6, which indicates the presence of weak organic contamination and corresponds to beta-mesosaprobic conditions. In the zone below Novosibirsk, the saprobity index was 2.0, which indicates an increase in organic pollution and corresponds to beta-mesosaprobic conditions. An increase in the level of eutrophication contributes to a change in the structure of zooplankton. This is reflected in a significant decrease (2.4 times) in the species diversity of zooplankton and a significant increase in quantitative indicators: abundance — 3.2 times, biomass — 2.8 times.

РАННЕ-ЛЕТНИЙ ЗООПЛАНКТОН ОЗЕР ВОЖЕ И ЛАЧА (ВОЛОГОДСКАЯ ОБЛАСТЬ)

In June 2015, zooplankton (Cladocera, Copepoda, Rotifera) of lakes Vozhe and Lacha, Svid’ River and the headwaters of the Onega River (catchment of the Onega River, White Sea basin) was examined. It was found that crustaceans (mainly the copepods Mesocyclops leuckarti and Eudiaptomus gracilis) dominated the community. The biomass of zooplankton (<1 g / m3) indicated a low food supply for fish (poorly fed water bodies), compared with the beginning of the 1970s, it decreased by 4–10 times. The composition and structure of the community characterized the ecosystem status of the Lake Vozhe as eutrophic, and Lake Lacha as mesotrophic. Changes in the structure of zooplankton over 40 years testified to the eutrophication of the ecosystem of Lake Vozhe and stabilization at the level of mesotrophy of Lake Lacha. In the lakes, the dispersal and relatively high abundance of some thermophilic species (Polyarthra luminosa, Thermocyclops crassus), indicators of eutrophic conditions that were previously absent in the community, were revealed. The productivity (14–34 cal / m2 × day) and the respiration rate of zooplankton (61–122 cal / m2 × day) of the lakes corresponded to the level of northern oligotrophic water bodies. It was shown that at the beginning of summer a significant part of the zooplankton production was consumed by planktonic predators (mainly copepods). Fishes had access to about 15% of the daily production of zooplankton in Lake Vozhe and up to 43% in Lake Lacha. A small proportion of filter feeders (30–60% of the total biomass) was recorded in the modern zooplankton of lakes. By 2015, the filtration capacity of plankton from lakes Vozhe and Lacha decreased by an order of magnitude compared to that in the 1980s. The low self-cleaning ability of lake waters is discussed as the main reason for the growing organic pollution and increased silt accumulation in their ecosystems.

Ecodiagnostics of different types of lakes in the Nizhny Novgorod Region based on indicators of the species structure of zooplankton

The research assesses the state of different types of lakes in specially protected natural areas of the Nizhny Novgorod Region and the anthropogenically disturbed territory of Nizhny Novgorod. The trophic status of water bodies was determined using the trophic status index (TSISD). It has been established that most of the lakes have eutrophic and mesotrophic status. The analysis of the species structure of zooplankton in water bodies has been carried out. The species richness of both lakes of the protected areas and urban lakes was high. Along with eurybiontic species, alien and rare species of zooplankton were identified. Significant differences in the indicators of the species structure were established, however, no critical values of the abundance, biomass, Shannon and Pielou indices were recorded. Most of the identified zooplankton species were indicative. On the basis of the Pantle-Bukk saprobity index in the Sladecek modification, the water quality class was established. The reservoirs were characterized by quality class IIIII (clean-moderately polluted water). In some lakes an excess of the maximum permissible concentrations of ammonium, nitrite, iron, manganese, copper, zinc, lead has been established. However, in general, in terms of a set of indicators, water bodies are in a satisfactory condition. In order to objectively assess the ecological state of aquatic communities, to predict possible changes and develop recommendations for the conservation of species diversity, it is important to carry out regular monitoring studies.

Rotenone for exotic trout eradication: nontarget impacts on aquatic communities in a mountain lake

Beaulieu J, Trépanier-Leroux D, Fischer JM, Olson MH, Thibodeau S, Humphries S, Fraser DJ, Derry AM. 2021. Rotenone for exotic trout eradication: nontarget impacts on aquatic communities in a mountain lake. Lake Reserv Manage. 37:323–338. Rotenone is widely used in lake and reservoir management for the eradication of exotic fish. However, nontarget effects of rotenone on freshwater organisms such as zooplankton and macroinvertebrates are of concern because of the ecological importance of these organisms in aquatic food webs as a resource base for fish, especially when rotenone is applied to lakes prior to native fish reintroduction. The objective of our study was to determine the effects of rotenone on nontarget zooplankton and macroinvertebrate species assemblages in a headwater mountain lake where rotenone was applied to remove exotic brook trout (Salvelinus fontinalis; Banff, AB Canada). We found strong negative rotenone impacts on the community structure and density of crustacean zooplankton, and to a lesser extent on macroinvertebrates, lasting for at least 1 yr after the rotenone treatment. Our study offers 2 unique insights that differentiate from rotenone studies on other lakes: (1) the persistent and almost complete eradication of crustacean zooplankton in the following summers, 11 months after rotenone treatment, and (2) a considerable shift in the macroinvertebrate community composition, likely resulting from combined effects of both nontarget rotenone effects on taxon density and trophic interactions associated with the eradication of brook trout from the lake. We advocate that assisted recolonization in the restoration of aquatic food webs could play an important role in facilitating nontarget aquatic community recovery following lake rotenone treatment.

Multi-scale and multi-system perspectives of zooplankton structure and function in Canadian freshwaters

This review provides a Canadian perspective on freshwater zooplankton diversity and ecology across scales and systems. It aims at describing how zooplankton are diverse in forms and functions, and constitute a key component of plankton food webs, a model for ecological theories and a sentinel for monitoring ecological integrity and function in lakes facing environmental changes and anthropogenic stressors. These objectives are addressed across a continuum of scales (continental, regional and local) and systems (reservoirs, lakes and ponds). This perspective shows that the environmental control of zooplankton biodiversity, community structure and function in Canada is complex and variable. Zooplankton communities demonstrated a wide range of responses to anthropogenic disturbances across scales and systems due to interactions with watershed biogeochemistry and climate. This review supports the Multiple Forces hypothesis where forcing by abiotic factors (climate, nutrients, morphometry and chemistry) has a fundamental role at continental scale over Canadian ecoregions, and at regional scale in the Boreal ecozones. In contrast, forcing by biotic factors (algal resources and predators) is relatively more influential at local scale, in resort and urban regions. The challenge for future research will be to combine all new concepts and approaches in a global perspective to better understand the responses of freshwater zooplankton to multiple environmental changes and anthropogenic stressors in Canada.

Zooplankton community structure in Cengkok Coastal Water and it’s around, Teluk Banten

Cengkok coastal waters of Banten Bay are one of the waters that have many anthropogenic, industrial, and aquaculture activities. Zooplankton would like to become a bioindicator for the water’s condition. This study aimed to analyze the biodiversity and structure of the zooplankton community in waters. The study was carried out, from May to September 2019 at five stations. Data analysis calculating the value of composition, abundance, similarity index, biological index, and PCA. Based on the study obtained, the zooplankton consisted of 17 classes and 47 genera. Based on location and time, respectively, the average composition of Malacostraca (47.2% and 49.8%) and Ciliata (40.6% and 37%). Based on location and time observation, the average diversity index (H’) was (0.8-1.6) and (1.2-1.6); evenness index was (0.7-0.8) and (0.6-0.9); and index dominance was (0.3-0.6) and (0.3-0.4) respectively. The PCA results divided into 3 groups and the results of the similarity index showed the zooplankton abundance had the highest similarity value at Stations 3 and 5 (0.829) and based on water parameters showed that the highest similarity is 0.98. Based on the community structure index, it is found that the condition of the zooplankton structure community in Cengkok coastal waters (Banten Bay) was medium stressed.

The Role of External Factors in the Variability of the Structure of the Zooplankton Community of Small Lakes (South-East Kazakhstan)

The variability of hydrochemical parameters, the heterogeneity of the habitat, and a low level of anthropogenic impact, create the premises for conserving the high biodiversity of aquatic communities of small water bodies. The study of small water bodies contributes to understanding aquatic organisms’ adaptation to sharp fluctuations in external factors. Studies of biological communities’ response to fluctuations in external factors can be used for bioindication of the ecological state of small water bodies. In this regard, the purpose of the research is to study the structure of zooplankton of small lakes in South-East Kazakhstan in connection with various physicochemical parameters to understand the role of biological variables in assessing the ecological state of aquatic ecosystems. According to hydrochemical data in summer 2019, the nutrient content was relatively high in all studied lakes. A total of 74 species were recorded in phytoplankton. The phytoplankton abundance varied significantly, from 8.5 × 107 to 2.71667 × 109 cells/m3, with a biomass from 0.4 to 15.81 g/m3. Shannon diversity index of phytoplankton in the lakes at high altitude varied from 1.33 to 2.39 and from 0.46 to 3.65 in the lakes at lower altitudes. The average weight of the cells of algae species varied from 0.2079 to 1.5076 × 10−6 mg in the lakes at lower altitudes, the average weight of the cells of algae species changed from 0.6682 to 1.2963 × 10−6 mg in the lakes at higher altitudes. Zooplankton was represented by 58 taxa. The total abundance of zooplankton varied from 0.05 to 169.00 thousand ind./m3 with biomass of 0.51–349.01 mg/m3. Shannon diversity of zooplankton in the lakes at lower altitude fluctuated from 0.42 to 2.32 and it was 0.66–1.77 in the lakes at higher altitudes. The average individual mass of specimens in zooplankton in mountain lakes ranged from 0.021 to 0.037 mg and varied from 0.002 to 0.007 mg in other lakes. The main factors in the development of the structure of zooplankton communities in small lakes were temperature, TDS, the content of nitrates, phosphates, and the composition and biomass of planktonic algae. The hydrochemical and biological data of the investigated lakes indicated their organic pollution. Our results once again confirmed the applicability of structural variables of zooplankton in assessing water quality.

Short Communication: Zooplankton as indicator of trophic status of lakes in Ilmen State Reserve, Russia

Abstract. Mashkova IV, Kostryukova AM, Shchelkanova EE, Trofimenko VV. 2021. Short Communication: Zooplankton as indicator of trophic status of lakes in Ilmen State Reserve, Russia. Biodiversitas 22: 1448-1455. Zooplankton is a potentially powerful tool for assessing the trophic state of aquatic ecosystems. The current paper studied taxonomic composition and biomass of zooplankton communities in ten lakes within Ilmen State Reserve, Chelyabinsk region, Russia and identified the influence of trophic status on its formation. Integrated samples were taken from epilimnion in the summer of 2016-2019. Several criteria were used to determine trophic status: the taxonomic structure and biomass of zooplankton; some hydroecological indicators some hydroecological indicators and the Carlson index. The trophic status of the studied lakes, determined based on the zooplankton biomass, revealed that most of the lakes were in the status of mesotrophic. The number of zooplankton species in the lakes was 44 with Pleuroxus laevis, Bosmina longirostris, Simocephalus vetulus were the most numerous species in mesotrophic lakes; while Chaetonotus ploenensis, Keratella quadrata frenzeli, Leptodora kindti are rare. Zooplankton communities of Bolshoye Miassovo and Maloye Miassovo Lakes were characterized by high species diversity and considered as one of the most significant among the foothill lakes of the eastern slope of South Ural. The study reveals that hydroecological assessment of the ecological status is not exactly precise, as values are not stable and can change not only under the anthropogenic influence but also due to many natural abiotic environmental factors. The research shows that species composition and biomass of zooplankton communities could provide a more accurate assessment of the trophic status of water-bodies.

Zooplankton taxonomic and functional structure is determined by macrophytes and fish predation in a Neotropical river

Habitat structure and predation are major factors that influence the distribution of zooplankton species and functional traits. Here, we analyzed how the structure provided by macrophytes (richness, Shannon’s diversity, and biomass) and potential predation by small-bodied fishes (richness and abundance) determine the richness of species and functional traits of zooplankton, as well as the spatial dissimilarity (beta-diversity) of species and traits. Zooplankton, fish, and macrophytes were simultaneously sampled across a gradient of 30 multi-species macrophyte beds. We assessed spatial patterns of zooplankton under taxonomic and functional approaches, using linear regression models, Generalized Dissimilarity Models, a Structural Equation Model, and a Fourth-Corner Analysis. Zooplankton taxonomic beta-diversity was most represented by the turnover component and zooplankton functional beta-diversity by nestedness. Zooplankton taxonomic richness and taxonomic beta-diversity were positively related to macrophyte biomass, richness, and Shannon’s diversity, whereas zooplankton functional richness and functional beta-diversity were positively related to fish richness and abundance. Macrophyte biomass and diversity oppositely influenced fish structure, which had influence on zooplankton structure. Macrophytes also negatively influenced the zooplankton traits such as body size, reproduction type, habitat, lifespan, and predatory escape response and positively influenced the trait feeding type. Fish were negatively related to the trait body size. The spatial structure generated by macrophyte beds and fish community determined the distribution of zooplankton species and functional traits.

Community structure of gelatinous zooplankton in a temperate ecosystem: Spatial patterns and underlying drivers

Gelatinous zooplankton (GZ) have long been regarded as organisms taking over perturbed systems (e.g. competing with fisheries and damaging aquaculture), but more detailed studies are required in order to better understand their role in marine ecosystem functioning. The present study characterised the GZ in the Bay of Biscay (BoB), (1) determining biodiversity, abundance and community composition of GZ assemblages, and (2) exploring the influence of oceanographic variability on GZ communities. Simultaneous GZ and oceanographic samples were obtained in May 2011 from 100 hydrographic stations. From the 30,194 GZ specimens analysed, 19 taxa were identified within Appendicularia, Thaliacea, Hydrozoa, Scyphozoa, and Tentaculata classes. There were few highly abundant taxa (e.g. Fritillaria pellucida represented almost the 60% of the collected individuals), but most of the species were diverse and less common. The most common species showed heterogeneous spatial abundance patterns, structuring 6 assemblages. Spatial configuration of GZ was shaped by depth, mean salinity and total chlorophyll a, suggesting a close relationship with main mesoscale oceanographic features in the BoB, such as shelf-break fronts and river plumes. This novel information complements the limited existing information of the main abundant gelatinous species within the “Bay of Biscay and Iberian coast ecoregion” of the Marine Strategy Framework Directive and could provide useful data for future ecosystem-based monitoring efforts.

Diversity and Structure of Pelagic Zooplankton (Crustacea, Rotifera) in NE Poland

This study presents the diversity and structure of pelagic zooplankton in north-eastern Poland. The research was conducted in 47 lakes with different trophic conditions in the middle of summer. Samples were collected close to the deepest part of the lakes to avoid the diverse benthic and littoral zones. We found 119 zooplankton species of which 32 were Cladocera, 16 were Cyclopoida, 4 were Calanoida, and 67 were Rotifera. We determined which species occurred most frequently in the region, as well as the species that were characteristic of different trophic conditions. We also recorded the presence of eight cold-adapted species which some of them are considered as glacial relicts (e.g., Eurytemora lacustris, Heterocope appendiculata, Cyclops lacustris). Our research revealed potential glacial refugia for planktonic species in 14 lakes of NE Poland. Our study suggests that the presence of stenotherm species may be an excellent indicator of the ecological status of deep lakes and could be considered in lake monitoring programs. Furthermore, we did not find Bythotrephes longimanus which has been reported from Poland. Instead, we found that B. brevimanus was the most common representative of the genus in the study area.

Plankton Community Structure and Water Environment Conditions in The Pelintung Industry Area, Dumai

This research was conducted in July 2020 in Pelintung Industrial Area Waters, Dumai City, Riau Province. The purpose of this study was to determine the community structure of phytoplankton and zooplankton and the condition of their aquatic environment. The method used in this research is a survey method. The phytoplankton community structure shows H 'values ??ranging from 3.62 to 4.02, E values ??ranging from 0.78 to 0.85. and C values ??ranged from 0.08 to 0.12 while the zooplankton community structure values ??for H 'values ??ranged (0.0000 - 2.2140, E values ??ranged (E) (0.0000 - 0.6665), and C values ??ranged (0.2325 - 1.0000) For the abundance of phytoplankton 18.90 ind / L - 55.56 ind / L and zooplankton 10.29 - 23.05 ind / L, this value shows that the waters of the Pelintung industrial area are still relatively good, not yet polluted from being able to support biota. Nitrate concentrations in these waters range from 0.096 to 0.179 ppm while Phosphate ranges from 0.084 to 0.106 ppm.

Effects of diclofenac on sentinel species and aquatic communities in semi-natural conditions

Due to the potential hazard of diclofenac on aquatic organisms and the lack of higher-tier ecotoxicological studies, a long-term freshwater mesocosm experiment was set up to study the effects of this substance on primary producers and consumers at environmentally realistic nominal concentrations 0.1, 1 and 10 µg/L (average effective concentrations 0.041, 0.44 and 3.82 µg/L). During the six-month exposure period, the biovolume of two macrophyte species (Nasturtium officinale and Callitriche platycarpa) significantly decreased at the highest treatment level. Subsequently, a decrease in dissolved oxygen levels was observed. High mortality rates, effects on immunity, and high genotoxicity were found for encaged zebra mussels (Dreissena polymorpha) in all treatments. In the highest treatment level, one month after the beginning of the exposure, mortality of adult fish (Gasterosteus aculeatus) caused effects on the final population structure. Total abundance of fish and the percentage of juveniles decreased whereas the percentage of adults increased. This led to an overall shift in the length frequency distribution of the F1 generation compared to the control. Consequently, indirect effects on the community structure of zooplankton and macroinvertebrates were observed in the highest treatment level. The No Observed Effect Concentration (NOEC) value at the individual level was < 0.1 µg/L and 1 µg/L at the population and community levels. Our study showed that in more natural conditions, diclofenac could cause more severe effects compared to those observed in laboratory conditions. The use of our results for regulatory matters is also discussed.

Dynamics of Zooplankton Composition in the Lower Northern Dvina River and Some Factors Determining Zooplankton Abundance.

—The long-term dynamics of the taxonomic composition of zooplankton in the lower reaches of the Northern Dvina River and the effect of some hydrochemical factors on its abundance have been studied. It is found that the species list of the zooplankton has included 141 species over 50 years: it consisted of a total of 98 taxa in 1965 and 104 taxa in 2012–2019. The results of analyzing the spatiotemporal abundance distribution of the zooplankton and its taxonomic groups are presented. A significant increase in abundance (on account of copepods) and changes in the taxonomic structure of zooplankton have been revealed in the lower parts of the study water area. In 2019, changes in the structure-forming complex of zooplankton were noted for the first time over the study period. It is found that species diversity reaches high values in waters classified as “heavily polluted” and “dirty,” which is evidence for a complex structure of zooplankton communities. The main factor influencing the horizontal distribution of the zooplankton abundance is the dissolved oxygen content of water.

Количественные показатели и трофическая структура зоопланктона разнотипных участков мелководной зоны Мешинского залива Куйбышевского водохранилища

The trophic structure and quantitative characteristics of zooplankton in four shallow water areas of Meshinsky Bay of Kuibyshev Reservoir were studied in the summer and autumn seasons. The sites differed in their protection from wind and wave impacts, and in intensity of macrophyte overgrowth. The maximum species richness of zooplankters feeding in the water column was observed in open and vegetation-free shallow water and foraging from the surface of the substrate in closed areas, overgrown mainly with one type of submerged plant. The highest quantitative indicators of zooplankton in all areas were observed in summer. Regardless of the season, the maximum abundance and biomass of communities was observed in protected shallow water in thickets of Potamogeton lucens L. This is associated with the density of vegetation cover protecting invertebrates from predation by fish.

苏州工业园区湖泊后生浮游动物群落结构及影响因子

苏州工业园区地处长江流域下游，随着城市化进程的不断推进，园区水生态系统结构与功能的稳定面临严峻考验。浮游动物作为水生态系统的重要组成部分，探究其群落结构的形成机制对生物多样性保护及生态系统健康发展具有重要意义。为深入了解苏州工业园区五个主要湖泊后生浮游动物群落结构的动态变化及影响因子，于2018年7月至2019年6月进行4次调查。研究共检出后生浮游动物112种（轮虫65种、枝角类29种、桡足类18种），其中优势种12种（轮虫10种、枝角类和桡足类各1种）。Jaccard相似性分析表明，湖泊间后生浮游动物物种组成整体处于中等相似水平。后生浮游动物密度呈现出显著的季节和湖泊差异，而生物量、Shannon-Wiener多样性指数、Pielou均匀度指数以及Margalef丰富度指数仅存在显著的季节差异。聚类分析结果表明，夏季和秋季后生浮游动物群落结构最为相似。RDA分析表明，水温、溶解氧和pH是影响园区湖泊后生浮游动物群落结构的主要环境因子。Pearson相关性分析表明，湖泊面积与后生浮游动物群落结构无显著相关关系，样点近岸距离与生物量具有显著的正相关关系。基于水质评价标准和物种多样性指数可知，园区湖泊水质整体处于轻-中度污染水平。研究表明苏州工业园区五大湖泊后生浮游动物群落结构表现出同质化趋势；季节变化、环境因子以及样点近岸距离是调控群落结构形成的主要因素。;Suzhou Industrial Park is located in the lower reaches of the Yangtze River Basin. With the continuous progress of urbanization, the stability of structure and function of the aquatic ecosystem in the Park is facing severe challenges. Zooplankton, as an important part of the aquatic ecosystem, is of great significance for the biodiversity protection and healthy development of the ecosystem by researching the formation mechanism of its community structure. Moreover, zooplankton is very sensitive to environmental changes, and the water pollution status can be evaluated based on its community structure characteristics. To better understand the community structure and influencing factors of metazoan zooplankton in five lakes of Suzhou Industrial Park, four surveys were conducted from July 2018 to June 2019. At the same time, five physical and chemical factors of water body, lake area, and the closest distance from samples to the shore were measured. A total of 112 metazoan zooplankton species (including 65 species of Rotifera, 29 species of Cladocera, and 18 species of Copepoda) were detected in this study, in which 12 species were dominant species (including 10 species of Rotifera, 1 species of Cladocera, and 1 species of Copepoda). Jaccard similarity analysis indicated that the species compositions of metazoan zooplankton among lakes were moderately similar. The density of metazoan zooplankton showed the significant differences in different seasons and locations, while biomass, Shannon-Wiener diversity, Pielou evenness, and Margalef richness indexes only had significant differences in seasonal aspect. The results of cluster analysis suggested that the metazoan zooplankton community structure was the most similar in summer and autumn. It was revealed that temperature, dissolved oxygen, and pH were the main environmental factors affecting the community structure of metazoan zooplankton by redundancy analysis. Pearson correlation analysis indicated that there was no significant correlation between lake area and metazoan zooplankton community structure, while a significantly positive correlation between the distance from samples to the shore and metazoan zooplankton biomass was detected. Based on the water quality evaluation standard and species diversity indexes, the water quality of the lakes in the Park was at a light to moderate pollution level. Overall, the metazoan zooplankton community structure in the five lakes of Suzhou Industrial Park showed a trend of homogeneity, and the seasonal variation, environmental factors and the distance from samples to the shore were main factors regulating the formation of community structure. The results of metazoan zooplankton community structure could provide an effective reference for the restoration and development of lake water in the Park.

KOMPOSISI DAN STRUKTUR KOMUNITAS ZOOPLAKTON DI DANAU TALAGA, SULAWESI TENGAH

Study of composition and community structure of zooplankton in Talaga Lake was conducted from February to March 2019. The aimed of this research was to know the composition and structure of zooplankton in Talaga lake, Central Sulawesi. Samples were collected at four station by using purposive sampling method. The identification results have found 4 genus of zooplankton with each composition 71 % of Cyclops, 22 % of Daphnia, 0,34 % of Paramecium and 6,64 % of Chaoborus. The zooplankton abundance is around 11.6-17.2 ind/l. Community structure of zooplankton in Talaga Lake is unstable which shows by the low value of diversity index (0.68 to 0.8) and uniformity index (0,49-0,57). The value of dominance index which is in range 0.51-0.58 has also shown that there is dominant type of zooplankton.