Zooplankton Diversity Research Articles

ECOLOGICAL IMPACTS OF ECOHYDROLOGICAL INTERVENTION ON THE WETLANDS ALONG THE SOUTHEASTERN SHORE OF LAKE TANA, ETHIOPIA

Lake Tana watershed wetlands have critical functions of nutrient and sediment retention, biodiversity and hydrological functions. Although ecohydrological solutions have been proposed, a comprehensive study on the impacts of ecohydrology intervention in relation to biological aspects is limited. Information regarding the ecological impacts of ecohydrology based intervention approach in the wetland ecosystem plays an indispensable role in increasing biodiversity and improves water quality. Thus, the aim of this study was to investigate the impacts of ecohydrological intervention in relation to macrophytes, phytoplankton and zooplankton of the wetlands in Lake Tana shore. Quantitative characteristics of macrophytes and plankton sampling were conducted using transect and quadrat method along vegetation and water depth gradients. The biological data were measured on each fixed sampling point. Macrophytes, phytoplankton and zooplankton were significantly different (p<0.05) across the sampling sites. Low disturbed wetland supports higher abundance and diversity of macrophytes, phytoplankton and zooplankton than moderately and highly disturbed wetlands. Overall results of the study confirmed that biological abundance and diversity were associated with the level of disturbance of wetlands. Therefore, emphasis should be given to the factors which may lead to the degradation of wetland resources within and its catchment. Immediate ecohydrology based intervention approaches should be implemented to conserve and minimize further degradation of wetlands along the shore of Lake Tana.

Effects of seasonal hydrological regulation of cascade dams on the functional diversity of zooplankton: Implications for the management of massive reservoirs and dams

The construction of cascade dams has led to a lack of longitudinal connectivity in rivers, fragmentation of habitats, slowing of the spread of biota, and loss of biodiversity. Here, we examined the zooplankton functional diversity in a typical river with cascade dams and compared the differences between the upstream and downstream parts of the river during the dry and wet seasons. The findings were as follows: (1) during the dry season, the nutrient load in the lower reaches of the river increased, and the water quality deteriorated, while the conditions during the wet season did not change significantly; (2) during the dry season, the functional beta diversity of downstream zooplankton caused by cascade dams was significantly (p < 0.05) lower than that upstream, but this phenomenon was not prominent during the wet season; (3) during the dry season, environmental factors and dam numbers significantly affected the functional diversity of zooplankton, and the number of dams directly impacted the formation of the distribution pattern of zooplankton functional traits. These findings highlight the effects of the hydrological regulation of cascade dams in different seasons on the functional diversity of zooplankton and suggest that: 1) water retention times and pollution source inputs should be reduced during the dry season, 2) dedicated biological channels should be established to reduce the harm caused by clustered pollution to zooplankton, and 3) thermal pollution and strong scouring caused by large-scale flood discharge simultaneously should be avoided during the rainy season. Zooplankton functional diversity is sensitive to dam hydrological regulation, and we advise it be included as a critical indicator during ecosystem assessment in the dam management process, along with additional biological indicators are recommended.

The Effects of Water Level Fluctuation on Zooplankton Communities in Shahu Lake Based on DNA Metabarcoding and Morphological Methods.

Simple SummaryThe water level in Shahu Lake varies greatly during an annual cycle: ~4 m deep to nearly dry. Over the course of one year we studied the relationship between zooplankton diversity and the water level in Shahu Lake using DNA metabarcoding. The morphology method was compared with the DNA metabarcoding method to see whether the results were replicable. The results were highly consistent for α-diversity and the community composition of zooplankton using both methods; both methods also showed a significant relationship between the zooplankton community composition and water level. Our research contributes to the application of the DNA metabarcoding method and aquatic ecological investigations.Background: The water level of Poyang Lake (China) fluctuates seasonally. Shahu Lake, a smaller body of water connected to Poyang Lake during the wet season, is separated in the dry season. Due to a special fishing method termed ‘lake enclosed in autumn’, the water level is lowered and reaches its lowest point in January, which is <0.5 m deep in the middle of the lake. Our research investigated the effect of water level changes on the zooplankton community composition in Shahu Lake. Methods: We used both DNA metabarcoding method (MBC) (18S rRNA gene V4 region) and morphological method (MOI) to track the zooplankton community structure over four seasons in Shahu Lake (China). Results: Totals of 90 and 98 species of zooplankton were detected by MOI and MBC, respectively, with rotifers being the main zooplankton component. The α-diversity index of both methods increased from spring to summer and decreased from summer to autumn, reaching the lowest value in winter. NMDS and a cluster analysis showed that all zooplankton communities detected by MOI and MBC were significantly separated by season. The zooplankton community in winter was separated from that of the other three seasons, but the summer and autumn communities were more similar. Conclusions: Changes in the water level had significant effects on the zooplankton community composition. We found that MBC was more able to detect the differences in the zooplankton composition than MOI. MBC also had more advantages in copepod recognition. In our study, 37 species of copepods were detected by MBC, but only 11 species were detected by MOI. We concluded that MBC should be used to research the seasonal variations of zooplankton.

Studies on Limnological Characteristics and Zooplankton Diversity in Durgadahalli and MydalaLakes of Tumakuru, Karnataka State, India

The specific status of limnological characteristics and diversity of zooplankton in Durgadahalli and Mydala Lakes have been studied in the period 2017-19. Diversity of zooplankton in the selected two lakes identified 35 species of zooplankton. In Durgadahalli lake 20 species were recorded, of which 14 are rotifers, 4 are cladoceraus and 2 are copepods. Among the rotifers, family Brachionidae reported as highest number of species (11 species), of which Genus Brachionus contain 08 species. Similarly, in Mydala lake recorded 26 species of zooplankton among which 17 are rotifers, 7 are cladoceraus and 2 are copepods. In rotifers, family Brachionidae contains high number of species (10 species), in which Genus Brachionus (08 species) represents the highest number. Most commonly occurring species are Brachionus angularis, B. caudatus, Keratellatropica, Filinia longiseta, Ceriodaphnia cornuta, Ceriodaphniacornuta, Diaphanosomasarsi and Moina micrura. The highest zooplankton population was recorded in rotifera and lesser in copepod in both the lakes. The water remained moderately alkaline (pH 7.07 and pH 7.27) while Biochemical Oxygen Demand (3.0 mg/l each), Dissolved Oxygen (7.5 mg/l and 5.32 mg/l), TDS (167 mg/l and 272 mg/l), chloride (15 mg/l and 27.5 mg/l), hardness (40 mg/l and 81.5 mg/l) showed low mean values respectively.

Seasonal and spatial variability of zooplankton diversity in North Eastern Arabian Sea along the Maharashtra coast

Marine biology,marine ecology,Phytoplankton, marine algae, zooplankton, nekton, benthos, corals and coral reefs, ecology, zoogeography and systematics, primary production and experimental work on ecosystem including energy flow at different trophic levels, population dynamics and theoretical models, recycling of matter, influence of environmental factors on metabolic activity, marine microbiology, mariculture and experimental work on propagation of cultivable species, biology of fishes, marine reptiles, sea birds and mammals, physical, chemical, geological and meteorological features of the environments related to marine biology, marine environmental damage caused by pollution and engineering works, underwater observations, conservation of living resources, modifications in methodology and techniques and development of new apparatus related to marine sciences

Experimental observation on the effects of bighead carp (Hypophthalmichthys nobilis) on the plankton and water quality in ponds.

It is a common practice to improve the water environment of rivers and lakes in China by the enhancement and releasing (EAR) of silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis) for biomanipulation. However, the quantity of bighead carp and its effect on water quality and plankton community have been the focus of debate among ecologists. Herein, in order to more accurately simulate the environmental conditions of lakes, we selected earthen ponds with large areas adjacent to Lake Qiandao from May to August in 2016 to study the responses of water quality condition and plankton community to a gradient of bighead carp stocked alone. Experimental groups with different densities of carp stocked were set as follows: 12.1 (LF), 23.5 (MF), and 32.5 g/m3 (HF), and a control group with no fish (NF). Results showed that total phosphorus (TP) in the fish-containing groups considerably decreased, and the lowest chlorophyll-a concentration (chl-a) was detected in the MF group. The biomass accumulation of the crustacean zooplankton was suppressed after carp was introduced, but the diversity, richness, and evenness of the crustacean zooplankton were weakly affected, except in the HF group. Phytoplankton biomass especially that of cyanobacteria was grazed rapidly by fish in the MF and HF groups and biodiversity indices were considerably increased in the fish-containing groups, especially in the late stages of the experiment. At a fish stocking density of 23.5-38.8 g/m3, the highest efficiency in controlling cyanobacteria and promoting water condition was achieved, and the impact on zooplankton diversity was weak. Our results indicated that bighead carp can be included in the EAR of lakes and reservoirs, but the optimal density of bighead carp stocking should be carefully considered.

How Do Specific Environmental Conditions in Canals Affect the Structure and Variability of the Zooplankton Community?

The present study investigates the responses of zooplankton (including changes in their structure and diversity) to physicochemical and biological parameters in two artificial waterways. Water samples were collected monthly from the Bydgoszcz Canal, the Noteć Canal, and the Brda River during the growing season of April–October 2019. We analyzed how selected parameters (including water temperature, Secchi disk visibility, oxygen concentration, conductivity, and pH, as well as nitrate, phosphate, and chl-a concentrations) affected seasonal variations in zooplankton diversity (T) and density (N). In total, we recorded 98 species, and average zooplankton density was 320 ind/L. At all sites, the same zooplankton species were dominant: Keratella cochlearis among rotifers and the Cladocera Bosmina longirostris among crustaceans. Rotifers dominated qualitatively and quantitatively over crustaceans. Zooplankton density and biomass, as well as the number of zooplankton species, were higher in the Bydgoszcz Canal than in the Brda River or the Noteć Canal. This may be connected to the locks on the Bydgoszcz Canal slowing down water flow, thereby increasing macrophyte vegetation, which creates ecological niches supporting zooplankton development.

Spatial distribution of zooplankton in relation to some selected physicochemical water quality parameters of Lake Hawassa, Ethiopia

While scientific information on spatial variation of freshwater zooplankton is relevant to limnological studies, little information is available from the Ethiopian Rift Valley lake: Lake Hawassa. This study aimed at understanding the spatial distribution of the dominant zooplankton taxa in Lake Hawassa, Ethiopia. Collection of samples and in situ measurements of physico-chemical parameters were carried out at four sites for five consecutive months from April to August in 2019. Twenty-two species of zooplankton were identified. Among these, rotifers were the most important with regard to both species richness and abundance. Copepods were the second most important group in terms of species richness and abundance, whereas cladocerans were the least abundant taxa. All zooplankton groups were very rare at the inlet of the Tikur Wuha River, which could be mainly due to stress, associated with extreme turbidity. Rotifers were predominant at the inlet of influents from referral hospital revealing their adaptation to less clear water and pollution. Copepods attained their highest abundance at the macrophyte zone indicating their preference for water with high clarity and refuge. We concluded that the spatial variation of the zooplankton density in relation to water quality parameters has implications for the applicability of zooplankton as a cost-effective water quality assessment tool in lakes.

Environmental drivers of taxonomic and functional variation in zooplankton diversity and composition in freshwater lakes across Canadian continental watersheds

ABSTRACTCanada is home to more lakes than any other nation, but there is a fragmented and limited understanding of the ecological status of these water bodies. Zooplankton are excellent bioindicators of lake health, given their central food web position. To date, many studies have investigated the effect of individual stressors on zooplankton communities, mediated through changes in water quality (e.g., macronutrients, temperature, or chemicals). Increasingly, stressors act simultaneously in lakes, often over extended periods of time. As part of the NSERC Canadian Lake Pulse Network project, pelagic zooplankton were sampled in 624 lakes across Canada, spanning six continental drainage basins. We evaluated the effect of 40+ environmental variables on zooplankton diversity and community composition, considering both taxonomic and functional approaches. We also tested specific hypotheses on the relationships between zooplankton communities and environmental conditions, including eutrophication, calcium, chloride, and fish predation. We found that lake morphometry variables were among the most important predictors of zooplankton diversity, while water quality metrics were more critical in explaining variation in community composition. Our results also reveal significant heterogeneity across Canada, with contrasting effects of environmental drivers among continental watersheds, highlighting that response models cannot be assumed to apply universally.

The wind‐driven distribution of nearshore zooplankton in a stratified lake varies with their body size

Abstract Wind‐driven forces are expected to concentrate zooplankton along downwind shores in lakes and provide food subsidy to nearshore food webs, but the bathymetric complexity of nearshore areas could result in high spatial variability. Here we test: (1) whether zooplankton accumulate downwind on windy days, and whether the magnitude of accumulation varies with zooplankton body size and with nearshore bathymetric slope; and (2) whether nearshore zooplankton are more spatially variable than offshore zooplankton, and whether their spatial variability is related to wind conditions and to zooplankton body size. This study focuses on zooplankton distribution at the whole‐lake basin and at intermediate (10 m–1 km) spatial scales. Zooplankton were sampled repeatedly along four c. 1 km transects at each of the upwind and downwind ends of a 22.1‐km2 stratified lake basin. Two transects were oriented perpendicular to shore and two were parallel, one close to shore and the other further offshore. Zooplankton were sampled along each transect using an optical plankton counter morning and afternoon over 3 consecutive days, under a range of wind conditions, during early stratification (early June), mid‐stratification (mid‐July) and late stratification (late September). A 3D‐hydrodynamic model was used to help interpret the results. Small‐bodied zooplankton accumulated downwind during windy periods, reaching 8%–34% higher biomass than the basin‐wide average. This downwind accumulation of biomass was best explained by a partial (metalimnetic) upwelling displacing the epilimnion to the downwind end of the lake basin. Active upward movement of zooplankton is required to explain near‐surface biomass accumulation in this displaced water mass. Large‐bodied zooplankton accumulated in nearshore areas, regardless of wind conditions. Higher nearshore accumulation of large zooplankton was observed along transects following a shallow (1.9%) bathymetric slope but not along a steep (6%) slope. Large‐bodied zooplankton are more patchily distributed than small‐bodied zooplankton, both nearshore and offshore. The spatial variability of large zooplankton declined with increasing wind speed, but only at upwind sites. The patchy distribution of large‐bodied zooplankton is driven, or at least strongly influenced, by biological processes. The spatial distribution and patchiness of zooplankton varies with wind speed, zooplankton body size and nearshore bathymetry. Planktonic organisms are not passive drifters, and their patchiness and influx to certain parts of the lake during windy periods are both expected to affect the efficiency of trophic transfers in lake food webs.

Taxonomic and functional coherence of active and dormant zooplankton communities between perennial and temporary aquatic environments

Abstract We characterized the functional and taxonomic composition of the active and dormant communities from perennial lagoons and temporary ponds in a coastal plain. We sought to determine the degree of coherence between the egg bank and the active community within the same type of environment (temporary or perennial) and between environments subject to different hydrological cycles. We sampled the zooplankton community and environmental variables in six temporary ponds and five perennial lagoons in the dry and the wet periods of the hydrological cycle. Temporary ponds and perennial lagoons differed in abiotic conditions, with higher values of dissolved carbon in temporary ponds and higher values of salinity in perennial lagoons. The taxonomic coherence between active and dormant communities in temporary environments was greater than in perennial environments. In functional terms, we observed a high coherence between active and dormant communities for both types of environments. Our results highlight the need to conserve both temporary and perennial environments to assure the maintenance of zooplankton diversity. Although these environments are subject to the same set of climatic variables and pool of species, their idiosyncrasies are important forces promoting and sustaining biological diversity.

Dugotrajno praćenje želatinoznog makrozooplanktona mesoždera na području Dubrovačko-neretvanske županije (Hrvatska)

In the southern part the Adriatic, gelatinous macrozooplankton fauna is poorly known compared to the other taxa. Therefore, our goal was to collect and systematize all available phenological data and abundances of gelatinous organisms based on scientific surveys from 1996 to 2020 and a ”citizen science“ sighting program in the southern Croatian waters. The inter-annual variability and seasonality of planktonic Cnidaria and Ctenophora were described. A total of 590 reports was received from citizens, which summed up to result in 870 data together with the scientists’ records. In total, 15 species were recorded. Of these, scyphomedusa Pelagia noctiluca accounted for 34 %, followed by ctenophora Cestum veneris (19 %) and the scyphomedusa Cothylorhiza tuberculata (17 %). Mass occurrence was most frequently found in P. noctiluca and then in C. tuberculata and C. veneris. Isolated mass occurrence was recorded for the freshwater hydromedusa Craspedacusta sowerbii, found in Lake Kuti near the mouth of the Neretva River, and for the scyphomedusa Aurelia cf. solida. The three species A. solida, Mnemiopsis leidyi and C. sowerbii are not native to European waters. Considered that alien species are invading the Adriatic Sea and human impact and global warming are increasing, it is crucial to carefully monitor the occurrence of gelatinous zooplankton taxa and to conduct studies focused on deciphering their ecological impact in marine ecosystems. Therefore, our empirical analysis of 25 years of observations provides essential information on the variation of gelatinous zooplankton in the Southern Adriatic region.

Seasonal cycle of zooplankton standing stock inferred from ADCP backscatter measurements in the eastern Arabian Sea

We use ADCP (acoustic Doppler current profiler) backscatter, measured during October 2012 to December 2020 at three locations on the continental slope in the eastern Arabian Sea (EAS), to study the seasonal variation in zooplankton standing stock. The regression from backscatter to biomass is based on zooplankton sampling at these locations off Mumbai (northern EAS or NEAS), Goa (central EAS or CEAS), and Kollam (southern EAS or SEAS). Analysis of the data over 24–140 m shows that the backscatter and zooplankton biomass decrease from the upper ocean, whose bottom is denoted roughly by 215 mg m−3 biomass contour, to the thermocline; this decrease in biomass with depth is weaker in the SEAS. The standing stock, defined as the integral of the biomass over 24–120 m, varies seasonally in the NEAS and CEAS, but the seasonal cycle is weaker in the SEAS. The minimum of standing stock is attained towards the end of the summer monsoon and the maximum occurs during the winter monsoon. This seasonal variation of the standing stock is also evident in a monthly climatology. Since the biomass changes less from the upper ocean to the thermocline in the SEAS, the seasonal range of standing stock is lower in the SEAS compared to the CEAS or NEAS. Analysis shows a high correlation between the depth of the 215 mg m−3 biomass contour and standing stock in the NEAS and CEAS; this relation is weaker in the SEAS. This seasonal variation of the standing stock is in contrast to that of satellite-derived chl-a, which peaks in the EAS during the summer monsoon.

Diversity of Zooplankton in Lesser Himalayan River Gaula at District Nainital Uttarakhand

Zooplankton are small, microscopic, free-floating and weakly swimming animals found in all aquatic environments. They play an important role in aquatic food web and act as a vital food source for secondary and tertiary consumers. They also help to transfer energy lower to higher trophic level of organisms. Due to their shorter life span, large density, drifting nature and high species diversity they are being considered as indicator organisms for the physical, chemical and biological processes in the aquatic ecosystem. The present study was carried out on diversity of zooplankton in a lesser Himalayan river Gaula at Dist. Nainital Uttarakhand. A total 18 species of zooplankton were recorded in which 7 belong to Protozoa, 6 to Rotifera, 2 to Copepoda, 2 to Cladocera and 1 was belong to Ostracoda. Among them Protozoa was the most abundant group throughout the study period. During the present study it has been found that seasonal abundance of Zooplankton was highest during summer, moderate in winter and lowest during monsoon season. Keywords: Zooplankton, Species Diversity, Abundance, Seasonal Distribution, Organisms, aquatic ecosystem.

Seasonal variations influencing the abundance and diversity of plankton in the Swarnamukhi River Estuary, Nellore, India

An integrated approach was used to study the seasonal influence on the abundance and diversity of phytoplankton and zooplankton in the Swarnamukhi River Estuary (SRE) and the adjacent coast covering five stations by collecting monthly samples from the years 2014 to 2017. A total of 54 phytoplankton species conforming to four families and 58 zooplankton species conforming to nine families were recorded. Phytoplankton abundance and richness were high during pre-monsoon (PRM - 56410 cells/L) followed by monsoon (MON – 42210 cells/L). A similar trend was observed in the case of zooplankton, where abundance was recorded high during PRM (124261 ind./m3) followed by MON (111579 ind./m3). Moreover, phytoplankton and zooplankton were dominated by the diatoms and copepods, respectively. Both phytoplankton and zooplankton exhibited significant temporal (F= 26.4, p &lt;0.05) and spatial (F= 32.1, p &lt;0.05) variations. The higher density and abundance were recorded in the inner stations compared to the open sea. The present study reveals that the SRE have a rich diversity which could be attributed to a higher nutrient influx in the inner stations. The anthropogenic discharge from the surrounding aqua farms, agricultural land, and human settlement area could cause concerns for the local flora and fauna if a proper mitigation plan is not evolved through long-term monitoring study in this coastal region.

Functional diversity and groups of crustacean zooplankton in the southern Yellow Sea

Functional trait and functional diversity indices reflect the variations of community structure and indicate their responses to environmental stress. In this study, based on four functional traits, including body length, feeding type, trophic group, and reproductive mode, the functional diversity and functional groups of crustacean zooplankton from the southern Yellow Sea (SYS) were explored over four seasons of 2019. A total of 53 species were identified and categorized into six functional groups. Copepods with ambush-feeding and omnivore–carnivore diet (Group Ⅱ) were dominant in spring (55.6%), while omnivore–herbivore copepods (Group Ⅰ) were the most abundant group in the other three seasons (>54.7%). The comparable distributions of functional diversity indices in different seasons were most likely due to hydrological variations. The Changjiang River Diluted Water promoted the coexistence of multiple traits carried by different functional groups (high functional richness (FRic) and functional dispersion (FDis)), but the stability of ecosystem function in this water mass was vulnerable to the loss of individual species (low functional evenness (FEve)) in summer. In winter, as a result of the Yellow Sea Warm Current, warm-water taxa increased FRic and FEve, suggesting that the community could buffer environmental fluctuations more effectively. Moreover, distribution of FRic values indicates the possible range and influence intensity of the Yellow Sea Cold Water Mass.

Similar zooplankton responses to low pH and calcium may impair long-term recovery from acidification.

Throughout much of the 20th century, unprecedented industrial emissions have led to widespread acidification of regions in North America and Europe and, as lake water pH dropped, aquatic ecosystems have experienced dramatic declines in biodiversity. International emission-control agreements have led to sweeping increases in lake pH, however acid-structured zooplankton communities still persist in many lakes. Concomitantly, calcium concentrations have been declining as a legacy of acidification and are approaching or have reached concentrations that could represent a barrier to the re-establishment of zooplankton communities similar to those in non-acidified or circumneutral reference lakes. To understand how declining calcium may influence the re-establishment of zooplankton in acid-damaged lakes we manipulated calcium and pH using a factorial in-lake mesocosm experiment and assessed their individual and combined effects on a regionally diverse zooplankton assemblage. We found that the impacts of low calcium on zooplankton species were similar to those of acidification and, consequently, may prevent the recovery of acid-structured communities. Abundance of the larger bodied and acid-sensitive Daphnia pulex/pulicaria increased in high pH treatments, albeit nonsignificantly yet, by the end of our experiment, only two individuals were sampled among our 10 low calcium enclosures. In contrast, small acid-tolerant cladocerans, such as Daphnia catawba, Daphnia ambigua, and eubosminids maintained significantly higher abundances in low calcium treatments relative to all other treatment combinations. Although we did not detect an effect of calcium on mean body size, the disproportionately high abundance of small cladocerans in low calcium treatments resulted in low calcium communities with higher overall abundance and lower cladoceran evenness. Our results, along with a landscape comparison demonstrating parallel changes in zooplankton relative abundance from 34 historically acidified lakes, suggests that declining calcium will be an important, on-going factor that may limit the recovery of zooplankton, despite regional improvements in lake pH.

Zooplankton Diversity and Water Quality Assessment of Lentic Waters of Jammu, India

An attempt was made to study the abiotic parameters of three water bodies of Jammu region along with their impact on distribution and presence of zooplankton. The total of 49 organisms belonging to five groups of zooplankton viz Protozoa, Rotifera, Cladocera, Copepoda and Ostracoda were identified. Of the three stations, ostracods were recorded from station 1 only. Phylum Rotifera was observed to be dominant in all the three stations. Many pollution indicator species like Brachionus calyciflorus, Brachionus angularis, Keratella tropica, Polyarthra vulgaris, Filinia longiseta, Moina brachiata, and Chydorus sphaericus were recorded from Station 1. Both biotic and abiotic components indicate that station 1 is progressing towards eutrophication.

Using the Diversity, Taxonomic and Functional Attributes of a Zooplankton Community to Determine Lake Environmental Typology in the Natural Southern Boreal Lakes (Québec, Canada)

Herein, we used zooplankton as a study model for determining how biodiversity components as well as taxonomic and functional attributes reflect lake typology in the natural southern boreal lakes. We estimated the regional and local variation in zooplankton diversity and the community structure across a set of fourteen lakes within a national park. Regional diversity (γ diversity) accounted for 40 species including 20 rotifers, 10 cladocerans and 8 copepods. Local diversity (α diversity) averaged 15 species per lake. Spatial variation in β diversity was inversely related to spatial variation in α diversity. Inter-lake variation in zooplankton communities based on taxonomy, functional traits and biotic indices was explained by two major limnological gradients: namely lake trophic status and fish community. The community structure reflected a gradient of rotifer to calanoid copepod dominance in response to trophic status. Several key species of rotifers (Kellicottia longispina and Conochilus unicornis) and of small (Bosmina and Diaphanosoma birgei) or large (Daphnia catawba and Holopedium gibberum cf glacialis) cladocerans were good indicators of lake zooplankton typology, as in other boreal lakes. We distinguished two main groups of lakes: (1) oligotrophic lakes inhabited by brook trout and dominated by the calanoid copepods and (2) mesotrophic lakes inhabited by northern pike and dominated by rotifers. Overall, our study can help managers better define monitoring and conservation strategies for lake ecosystems in natural parks.

Composition and distribution of zooplankton species in the subtropical areas of the Northwestern Pacific Ocean

Based on the investigation data of 44 stations in the area 28°－35° N, 147°－154° E of the Northwestern Pacific Ocean by the research ship 'Songhang' in March 2019, we analyzed species composition and distribution of zooplankton to understand zooplankton community structure in the subtropical areas of the Northwestern Pacific Ocean. The results showed that a total of 456 zooplankton species (including planktonic larvae and unidentified species) were recorded in the surveyed area, which were belonged to 8 categories and 14 groups. There were 163 species of copepods, as the dominant group. The dominant species included 9 warm-water species, Eudoxoides spiralis, Neocalanus gracilis, Pleuromamma gracilis, Sagitta enflata, Doliolum nationalis, S. hexaptera, Euchirella rostrata, Nannocalanus minor and Mesocalanus tenuicornis, and one temperate species, Calanus jashnovi. Both the warm current indicator species S. hexaptera and the cold current indicator species C. jashnovi occurred simultaneously in the subtropical area, indicating that the Kuroshio Current and the Oyashio Current had an important impact on the diversity and temporal-spatial distribution of marine zooplankton. The average biomass was (31.64±23.81) mg·m-3, and the average abundance was (22.2±17.6) ind·m-3. The average values of purity index (C), eveness index (J), Shannon diversity index (H) and richness index (D) were 0.09±0.10, 0.76±0.10, 4.88±0.71, and 23.53±8.08, respectively. The spatial distribution of the four indices were uneven and irregular. During the study period, species composition of zooplankton in the Northwest Pacific was rich, species distribution was uneven, and community structure was stable.