Diversity Of Zooplankton Communities Research Articles

Assembly mechanism and stability of zooplankton communities affected by China's south-to-north water diversion project

Water diversion can effectively alleviate water resource shortages and improve water environmental conditions, while also causing unknown ecological consequences, in particular, the assembly mechanism of zooplankton communities in the affected areas will become more complex after long-term water transfer. Taking Nansi Lake, the second largest impounded lake along the eastern route of China's South to North Water Diversion Project (SNWDP), as an example, the composition and diversity of zooplankton communities in the lake area and estuaries during the water diversion period (WDP) and non-water diversion period (NWDP) were studied. The potential assembly process of zooplankton communities was further explored, and the stability of communities in different regions during different periods was compared. The related results indicated that the changes in water quality conditions induced by water diversion had a relatively weak impact on the zooplankton communities. In the assembly mechanism of zooplankton communities, stochastic process played a more important role during both WDP or NWDP, and the proportion of deterministic process was relatively higher during NWDP, which may be related to the greater role of total nitrogen (TN) in the assembly of the zooplankton communities. The network analysis and cohesion calculation results showed that the stability of the zooplankton communities in the lake area sites was higher than that in the estuary sites, and the stability during NWDP was higher than that during WDP. In sum, the stability of zooplankton communities displayed a degree of change affected by water diversion activities, but the community assembly was not significantly influenced by the water quality fluctuations after about relatively long-term water diversion. This study provides an in-depth understanding of the ecological effects of water diversion on the biological communities in the affected lake, which is beneficial to the management and regulation of long-term water diversion projects.

Spatio-temporal species distribution models reveal dynamic indicators for ecosystem-based fisheries management

Abstract Many economic sectors rely on marine ecosystem services, and holistic management is necessary to evaluate trade-offs between sectors and facilitate sustainable use. Integrated ecosystem assessments (IEA) integrate system components so that managers can evaluate pathways to achieve desired goals. Indicators are a central element of IEAs and capture the status and trend of individual components and should be sensitive to changes in the system; however, most indicators are aggregated over space and time as annual values, potentially leading to incomplete or inaccurate inferences about system change. Here, we demonstrate the utility of spatially and temporally explicit ecological indicators by fitting multivariate spatio-temporal models to survey data from the northeast US Shelf Ecosystem, encompassing three distinct ecoregions: Georges Bank, Gulf of Maine, and mid-Atlantic Bight. We evaluate three case studies to explore how these models can help assess ecosystem performance relative to management objectives, such as to: (1) identify dominant modes of variation in zooplankton communities; (2) quantify components of system stability; and (3) assess the density-dependent condition of groundfish over time. Collectively, these three examples demonstrate multiple interesting processes, but particularly highlight the rapid zooplankton changes and associated changes in benthivore condition and stability in the Gulf of Maine. Attributing changes in ecosystem indicators to localized processes is difficult using conventional “regionally aggregated” indicators, so this example highlights the benefits of spatio-temporal methods for integrated ecosystem analysis in this and other regions.

Phytoplankton and zooplankton succession during the dry–refilling cycle: A case study in large, fluctuating soda lakes

Abstract Aquatic ecosystems in arid regions are important habitats for aquatic wildlife and also support species biodiversity. Soda lakes in endorheic drainage basins, so‐called amplifier lakes, are sentinels of climate change and are of scientific significance. Here we present the results of a long‐term study (20 years) of the Torey lakes, Transbaikalia, Russia, including the period from the maximum capacity of the Torey lakes through to aridification, and then to the initial phase of refilling. Our aim was to determine the response of planktonic communities in the lakes to environmental change over this period. We conducted our studies during various parts of the hydrological cycle, including three phases for Lake Zun‐Torey (high [1999, 2003], intermediate [2007, 2011] and low [2014, 2016] water levels) and two phases for Lake Barun‐Torey (high level [1999, 2003] and the initial refilling phase [2014, 2016, 2018, 2020]). Lake Barun‐Torey dried up completely in summer 2009, and since 2013 has been undergoing initial refilling. Lake Zun‐Torey dried up in the autumn of 2017. Temporal variation in planktonic communities differs for each lake. We identified four stages of changes in the planktonic associations during the aridification of Lake Zun‐Torey (the phytoplankton experienced a decrease in abundance and biomass, and was dominated by green algae and diatoms; the zooplankton underwent a decrease in species diversity and an increase in total abundance and biomass, which were caused by an increase in the abundance of some crustacean species) and three stages of changes as the lake level fell and during the initial refilling of Lake Barun‐Torey (the plankton communities increased in species richness and abundance in the transient pools). These results show the complexity of long‐term community dynamics in arid‐zone soda lakes. They have revealed how phytoplankton and zooplankton community diversity and structure can vary with changing environmental conditions and may pass between distinct states related to the stages of the hydroperiod.

STRUCTURE AND DIVERSITY OF ZOOPLANKTON COMMUNITY IN TAABO RESERVOIR (COTE DIVOIRE)

Zooplankton play a substantial role in the ecology of aquatic ecosystems and are usually used as bioindicators to assess their health. This study aims to assess the structure and diversity of Zooplankton community in Taabo reservoir. Zooplankton were sampled at five sites along a transect of seven kilometers every 45 days from November 2017 to October 2018 using a net of 20µm mesh size. A total of 77 taxa belonging to four groups (59 rotifera, ten cladocera, five copepoda and three otherzooplankton). High diversity of zooplankton (more than 87%)was reported in the littoral areas (S1 and S5).The proportion of very frequent taxa are the most numerous at all the sampling sites, and Sorensen similarity indexes between these sites are higher than 80%. Zooplankton abundance was higher during the dry season at all sites. Zooplankton community of Taabo reservoir was qualitatively (76.6 % of the taxonomic richness) and quantitatively (more than 68.35% of the relative abundance) dominated by rotifers group.Shannon-Weaver diversity and Pielou Evenness indices were lower in long rainy season than the other seasons. The RDA analysis shows that the abundances of zooplankton taxa such as Mesocyclops sp., Thermocyclops sp., Ceriodaphniacornulata and Diaphanosomaexcisumwere positively affected by conductivity, water depth, pH, TP, and TN. However, water transparency and temperature had positively influenced the abundances of zooplankton taxa such as Anuraeopsisfissa, Brachionusangularis, Brachionuscaudatus, Brachionusfalcatus, KeratellaLenzi, Keratellatropica, Hexathraintermediaire, Epiphanesmacrourus, Filiniaopoliensis, Lecaneleontine, and Nauplii.Zooplankton communitywas affected by anthropogenicdisturbances.

Impact of Colonizer Copepods on Zooplankton Structure and Diversity in Contrasting Estuaries

The impact of the occurrence of the non-indigenous species (NIS) Acartia tonsa, Oithona davisae, and Pseudodiaptomus marinus and of the range-expanding copepods Acartia bifilosa and Calanipeda aquaedulcis on the structure and diversity of zooplankton communities was analyzed using 18 years (1998–2015) time series from the contrasting estuaries of Bilbao and Urdaibai (Basque coast, Bay of Biscay). Changes in the structure of communities were assessed by using multivariate analyses of taxa abundances and changes in diversity by using descriptors of alpha, beta, and gamma diversity. The most evident changes occurred at the upper reaches of the estuary of Bilbao, where an abundant and less diverse brackish community, dominated by the NIS, A. tonsa and O. davisae, succeeded a low abundance and more diverse community of neritic origin. The later establishment of C. aquaedulcis was linked to further changes in the structure of the community and a progressive increase in diversity. The seasonal pattern of diversity at the inner estuary and the beta diversity in the estuary were also significantly affected by the arrival of the NIS and C. aquaedulcis. In contrast, the original low diversity brackish community of the estuary of Urdaibai, clearly dominated by A. bifilosa, was far less affected by the arrival of the same copepod NIS, and A. bifilosa remained as the species best related to the changes in zooplankton structure and diversity in the brackish habitats of the estuary.

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.

Characteristics and renewal of zooplankton communities under extreme environmental stresses in the oligotrophic hypersaline Arabian Gulf

Impacts of the exceptionally high temperature and salinity on species composition, abundance, biomass and diversity of zooplankton communities were examined in the central Arabian (Persian) Gulf in late winter and summer of 2010 and 2011. Remarkably diverse zooplankton assemblages were characterized with small calanoids (Paracalanus aculeatus and Temora longicornis), cyclopoids (Oithona nana, Oithona plumifera, Corycaeus flaccus and Corycaeus lautus) and harpacticoids (Euterpina acutifrons) with relatively low abundance and biomass. Overall, the low biomass and abundance were not significantly associated with phytoplankton, whereas zooplankton faunal similarities were significantly correlated with water properties measured as environmental distances across sampling sites. Spatially, the lowest abundance, biomass and diversity occurred in extremely saline nearshore waters off the western Qatar peninsula, whereas the highest abundance, biomass and diversity consistently appeared at northeast offshore locations that periodically encounter nutrient and species-rich but low-salinity water entering the Arabian Gulf via the Strait of Hormuz. Numerically, the relative dominance of calanoids along with lower salinity and high chlorophyll-a concentration in the northeast Arabian Gulf implies that zooplankton populations are likely replenished by the seasonal (summer) transport of species from the Gulf of Oman and the Arabian Sea, which may explain partly the high variations of species richness and zooplankton abundance previously reported in the region. Given increasing evidence of climate-change induced responses of zooplankton, our findings suggest that in the semi-closed Arabian Gulf resident populations stressed by the harsh environment are likely to continue to be sustained only by invading water masses during the summer.

A Study on Seasonal Variation in Zooplankton Abundance in Kadasgatti Minor Irrigation Tank of Bailhongal Taluk, Belagavi District, Karnataka State, INDIA.

Objectives: A study on seasonal variation in zooplankton community was undertaken to evaluate the present status of water quality at Kadasgatti minor irrigation tank (MIT) located in the northern transitional zone of Belagavi district. Methods and Statistical Analysis: Water samples were collected from January 2017 to December 2017. Physico-chemical parameters and qualitative and quantitative analysis of zooplankton were carried out. Pearson correlation was calculated using SPSS, IBM Version 21 software to find out interrelationships between water quality and zooplankton groups. Findings: A total of 52 species of zooplanktons were recorded during the study period with a total zooplankton abundance of 14327 individuals with a relative abundance of 35.42%. Rotifera was the dominant group with 27 species, followed by Cladocera, Copepoda and Ostracoda. The highest zooplankton abundance was observed in summer while minimum in post-monsoon season. Copepoda was highest abundant group during the entire study period with its maximum abundance during winter and gradually declined and reached to its minimum in post-monsoon. The presence of eutrophic indicator species like Brachionus calyciflorus, Brachionus angularis, Filina longiseta suggests eutrophication of the tank. Novelty: The study provides baseline data on the present status of the water body indicating that, anthropogenic activities, agricultural runoff are the main cause of eutrophication. Sustainable and holistic conservational strategies have to be adopted to protect the water body. Keywords: Cladocera; Copepoda; Eutrophication; Rotifera; Seasonal variation; Zooplankton abundance

A liquid seaweed extract (TAM®) improves aqueous rearing environment, diversity of zooplankton community, whilst enhancing growth and immune response of Nile tilapia, Oreochromis niloticus, challenged by Aeromonas hydrophila

A commercial seaweed liquid extract (TrueAlgaeMax, TAM®), previously showed a high content of phytochemical compounds and resulted in promoting growth and immune response of Nile tilapia, when applied as dietary supplementation. In the current study, the effects of applying TAM® as a natural agent to rearing water on growth performance, feed utilization, and immune response of Nile tilapia, Oreochromis niloticus, challenged by Aeromonas hydrophila were conducted. Also, zooplankton community, diversity, and abundance were evaluated in the cultured water. Five experimental groups (G0, G1, G2, G3, and G4) were exposed to different TAM® concentrations (0, 50, 100, 150, and 200 ml m‐3 of culture water, respectively). Healthy 450 mono-sex O. niloticus fingerlings (26.048 ± 0.050 g) were randomly stocked in glass aquariums (150 L aquaria−1, thee replicates treatment−1). The water in aquariums was renewed with a rate of 10% every 4 days and supplied with new freshwater with maintaining the respect TAM® concentrations. The feces and uneaten food were daily removed. The fish were fed at a level of 3% of body weight during the 70-days experimental period. The results revealed that TAM® exposed groups yielded higher significant growth performance, feed intake, and feed utilization compared to the control group. The non-specific immune response (total protein, albumin, globulin levels, and lysozyme activity) and antioxidant enzyme activities were significantly improved with increasing TAM® exposure levels. The resistance of O. niloticus against Aeromonas hydrophila challenge improved significantly in different TAM® treatments. Comparing to the control, TAM® treatments improved the zooplankton community, diversity, and abundance. Due to TAM® photobiotic, applying TAM® levels (especially G4) are significantly flourishing the abundance of Rotifera and Polychaeta, while, inhibiting the abundance of Nematoda, Trematoda, and Insecta. Finally, it can be concluded that the aqueous exposure to seaweed extract TAM® could improve fish growth performance, health status, and resistance against pathogenic bacteria challenge. In addition, it has a desirable modulation effect on natural microbiota in the fish rearing water.

How zooplankton communities are shaped in a complex and dynamic coastal system with strong tidal influence

Temperate coastal marine environments are typified by strong seasonality and highly productive annual spring phytoplankton blooms. However, in areas of strong tidal activity, coastal waters may remain in a state of low productivity year-round due to light limitation induced by deep mixing. Such high-nutrient low-chlorophyll (HNLC) environments can be found in British Columbia, Alaska, Argentina, and the United Kingdom. This study aimed to examine how zooplankton communities are shaped by tidally mixed environments through direct comparison of adjacent stratified and mixed regions on the British Columbia coast. Stations located in five distinct regions of coastal BC were sampled during the most productive months (April to July) over two years. The most seasonally stratified station was characterized by a higher biomass of large zooplankton species, including calanoid copepods and euphausiids. In contrast, the mixed regions had a higher abundance of small (<2 mm) zooplankton species and a prevalence of meroplankton taxa. Zooplankton communities in tidally mixed regions had indicator species that reflected source waters in an adjacent stratified area. However, despite different source waters, tidally mixed regions showed a convergence of community structure pointing to a common community modification process. It may be the result of a combination of advective processes, zooplankton vertical migration behavior, enhanced predation due to close contact with bathymetry and daytime transport to the surface, and a large contribution of meroplankton. In areas with strong tidal exchange, zooplankton communities were more similar than expected based on the physical and chemical characteristics of the water column alone. The mosaic of primary productivity regimes on the BC coast therefore translates into similar spatial scale variation in zooplankton communities, resulting in a spatially heterogenous prey field for zooplankton consumers.

Seasonal variation of zooplankton in Ba Lai river, Ben Tre province

The purpose of research is studying the variation of zooplankton community in Ba Lai river in Ben Tre province. Research was conducted in 2 seasons: rainy season (December, 2017) and dry season (March, 2018). There were 7 sampling points in Ba Lai river, Ben Tre province. Our study recorded 95 taxa zooplankton belong to 56 genera, 39 families, 12 orders, 8 classes and 5 phylums. Generally, Rotifers had highest munbers of species among 2 seasons. Rotifers were dominant in density and species composition at all sampling points in the rainy season. Copepods were dominant in density and species composition in the dry season. There were some marine species present at sampling points during the dry season. In addition, the Bray - Curtis analysis showed that the similarity of the zooplankton communities between rainy season and dry season at sampling points wasnot high. This suggests that there was a shift in the structure of the zooplankton community between rainy season and dry season. These are proof to prove the salinity rising in Ba Lai river in dry season. Although there is an irrigation dam to prevent the infiltration of salt water, but the infiltration of salt water is happening. A solution to preserve fresh water to provide local people in dry season is necessary.

Damming interacts with the flood pulse to alter zooplankton communities in an Amazonian river

Abstract Flow modification of lotic ecosystems is one of the main threats to global freshwater biodiversity. Commonly, and in the river studied here, modification results from hydroelectric dam installation. We evaluated the impacts of damming on zooplankton communities in the Amazonian floodplain of the Madeira River (Porto Velho, Rondônia, Brazil) following construction in 2012 of the run‐of‐river dam of Jirau Hydroelectric Power Plant. Using data sampled between 2009 and 2015, we tested for discontinuities in zooplankton community composition attributable to damming and the naturally occurring flood pulse. The flood pulse remained the main predictor explaining variation in zooplankton community structure even with the installation of the dam on the Madeira River. Despite this, discontinuities for the entire zooplankton community and for the main compositional groups (testate amoebae, rotifers, cladocerans, and copepods) were detected in relation to the dam (pre‐/post‐dam periods), mainly in ebb and low water, and with weaker evidence of dam effects during flood and highwater hydrological periods. A multivariate regression tree explained 9.6% of the variation in zooplankton communities and identified four groups: (1) flood and high‐water periods; (2) low water post‐dam; (3) low water pre‐dam; and (4) ebb hydrological periods. The deviance in each multivariate regression tree node was attributable to variation in eight rotifer, three testate amoeba, and three copepod taxa. Our study demonstrates that the flood pulse, dam construction, and interaction between both of these factors affect zooplankton community structure in the Madeira River. While for many zooplankton community variables, effects occurred mainly during ebb and low‐water periods, some effects were also observed during high water and flood periods. We thus recommend the establishment of a permanent environmental monitoring programme during all hydrological periods in tropical floodplain rivers and the addition of sampling sites downstream from dams. Many rivers in the world are increasingly disrupted by multiple dams, yet little is known of their effects, especially for run‐of‐river dams. Our study identified short‐term impacts of only one run‐of‐river dam on zooplankton communities. More research is needed on the effects of multiple run‐of‐river dams on zooplankton and other biota, especially in tropical floodplain rivers, so that negative effects can be understood and ameliorated.

Long-term effects of nutrient changes on rotifer communities in a subtropical lake

External nutrient loading has a major influence on the abundance, composition and diversity of zooplankton communities. To clarify how the reduction of nutrient loading during lake restoration interacts with other abiotic and biotic factors and how the interactive factors affect long-term changes in rotifer communities, we analyzed the relationships between the rotifer communities and environmental factors using a 17-year dataset. After the reduction of nutrients, both the abundance and biomass of rotifers declined, and the dominant rotifers changed from eutrophic-tolerant species to less tolerant ones. The lower TN:TP ratio that was caused by the imbalanced decrease in TN and TP after restoration promoted cyanobacteria, which negatively related to the resource-use efficiency of rotifers. Moreover, seasonal differences in the Shannon–Wiener index–TN relationships and the decrease in the Pielou index with the increase in water temperature implied there were interactive effects of water temperature and nutrients on species diversity. The study concluded that changes in rotifer abundance and community composition were mainly related to TN, but the changes in species diversity were mainly related to the interactive effects of the TN:TP ratio, water temperature and food quality. Our findings highlighted the effects caused by imbalanced nutrient changes on species diversity.

Spatial variation in zooplankton communities in relation to key environmental factors in the Yellow Sea and East China Sea during winter

The zooplankton composition, abundance, community structure, and diversity in the Yellow Sea and East China Sea, major wintering grounds of many fishery species, were studied based on net plankton samples collected in winter of 2016. A total of 68 taxa (mostly at the species level) were recorded. Copepods clearly dominated the zooplankton community, and the dominant species were Oithona similis, Paracalanus parvus, Microsetella norvegica, and Calanus sinicus. Three zooplankton communities (Groups 1–3) were identified via cluster analysis. Group 1, which was characterized by the highest mean total zooplankton abundance and lowest community diversity, mainly consisted of warm-temperate species found in the middle region of the southern Yellow Sea. Stations distributed in the northern East China Sea were included in Group 3, where many tropical and subtropical species were found and zooplankton exhibited the highest species number and community diversity. Group 2, which was located in the coastal area and transitional region between Groups 1 and 3, contained Labidocera euchaeta as the representative species. Seawater temperature was more important in shaping the spatial patterns of zooplankton communities than other environmental factors in the study area during winter. In addition, water currents showed a great influence on zooplankton composition and community structure. Overall, the results of this study provide information regarding food availability for wintering fish and contribute to a better understanding of zooplankton dynamics in the area during winter.

SEASONAL VARIATION OF DIFFERENT GROUPS OF ZOOPLANKTON OF A WETLAND IN RELATION TO SOME ABIOTIC FACTORS

The zooplankton community of the wetland was represented by Protozoa, Rotifera, Cladocera and Copepoda. The Protozoan population includes ciliates and flagellates and the maximum and minimum abundance were 223 and 2 ind./lit respectively. Rotifers, the largest group were represented by a minimum of 9 ind./lit and a maximum of 1425 ind./lit. Copepods, the second largest group, comprised a minimum of 1 ind./lit and a maximum of 708 ind./lit. The other group Cladocerans was found to be in lower profile which showed no definite pattern of their seasonal variation. In this wetland water temperature (WT) varied from 19.75oc to 34oc, transparency (TRN) from 31.3 to 82.5 cm, pH from 6.5 to 8.4, dissolved oxygen (DO) ranged from 1.3 to 10.6 mg/lit, total alkalinity (TA) from 62 to 76mg/lit, free CO2 from 5 to 30 mg/lit and biological oxygen demand (BOD) from 1.2 to 10.2 mg/lit. Although seasonal variation of zooplankton community is largely governed by abiotic factors, but pH exerted considerable influence.

Zooplankton communities in Cenderawasih Bay National Park, West Papua: can their composition be used to predict whale shark Rhincodon typus Smith, 1828 appearance frequencies?

The use of lift net fishing vessels in Cenderawasih Bay National Park (CBNP) along with the increased popularity of CBNP as an ecotourism area is suspected to have an impact on the behavior and population of its whale sharks Rhincodon typus Smith, 1828. The differing frequency of whale shark appearances along the waters of CBNP has been alleged to be related to the distribution of the whale sharks’ food sources, one of which is zooplankton. This preliminary research aimed to investigate the composition of the zooplankton community in CBNP based on distance from the coast and difference in locations, and to use the pattern of zooplankton compositional variation as a basis for indication of the frequency of whale shark appearances. There were clear differences in the composition and diversity of zooplankton communities among sampling stations, but these differences were not strong enough to infer the cause of the different whale shark appearance frequencies in different locations. Nevertheless, the waters of CBNP had an equal availability of zooplankton for whale sharks. With the increasing popularity of whale shark tourism, understanding the species’ feeding habits is critical to the sustainability of both the industry and the enigmatic species on which it depends.

Factors that drive zooplankton diversity in Neo-Tropical Savannah shallow lakes

Abstract Zooplankton is an important community in aquatic ecosystems due to its linkage between primary producers and secondary consumers also playing a key role in cycling of organic materials. Aim: Therefore, our objective was to evaluate the effects of physicochemical variables of the water on the diversity of zooplankton community in seven tropical shallow lakes of Brazilian savannah. Methods Zooplankton samples were taken using a bucket and filtered 200 L by a 64 µm-mesh-plankton-net, and preserved for subsequent identification. Water temperature, dissolved oxygen, pH, electrical conductivity, turbidity, chlorophyll-a, ammonium, nitrate, nitrite, total phosphorus, and soluble reactive phosphorus were measured. Results The turbidity (decreases the temperature, luminosity and the system productivity) and ammonium (increases the toxicity) values were the major factors responsible for structuring the zooplankton community. On the other hand, also nitrogen and phosphorus (increase the productivity) are limiting in savannah lentic systems for the zooplankton. The higher α diversity was positively associated with aquatic macrophytes (increase of niches and refuge), whereas lakes with geographic proximity increase the similarity in species composition, decreasing the β diversity. Conclusions We conclude that the deterministic processes (niche theory), due to species have different ecological requirements, are different responses to environmental gradients and increase the diversity in heterogenic lentic systems.

Effects of Climate, Limnological Features and Watershed Clearcut Logging on Long-Term Variation in Zooplankton Communities of Boreal Shield Lakes

In Canada, climate change and forest harvesting may both threaten the ecological integrity of boreal lakes. To disentangle the effects of natural variation in climate and lake environments from those of logging, we evaluated long-term variation (1991–2003) in zooplankton communities of six boreal lakes in Ontario. We monitored concomitantly changes in zooplankton abundance and composition in three undisturbed and three harvested lakes, five years prior and eight years after watershed clearcut logging. We tested the hypothesis that long-term natural variation in climate and lake environments will be more important drivers of zooplankton community changes than short-term impacts of logging. We used space/time interaction tests and asymmetric eigenvector maps to model zooplankton responses to environmental changes and logging. Year-to-year variation in zooplankton abundance and composition were almost an order of magnitude whereas among-lake variation was stable through time. Breakpoints in time series of zooplankton in each lake were not directly related to logging. Climatic and limnological features were the most important drivers of long-term variation in the zooplankton community, shading the effect of logging. These results highlight the need to better understand the pressures exerted by climate change on boreal lake ecosystems in the context of anthropogenic pressure, such as logging.

Impact of physico-chemical parameters on composition and diversity of zooplankton community in Nozha hydrodrome, Alexandria, Egypt

Impact of physico-chemical parameters on composition and diversity of zooplankton community in Nozha hydrodrome, Alexandria, Egypt

Does artificial drawdown affect zooplankton structure in shallow lakes? A short-term study in a tropical reservoir

Water level fluctuation by artificial drawdown is one management activity that has the potential to control macrophyte growth, but there is little knowledge of how this operational procedure affects other biotic components of the ecosystem. This study investigated zooplankton dynamics in response to artificial drawdown over a short timeframe (13 days) in a Brazilian reservoir, by examining the impact on zooplankton communities in two shallow lakes (Lake Pedra Branca-LPB, and Guarita-LG) connected to a reservoir (Salto Grande) that undergo sudden and remarkable fluctuations in their water levels. Zooplankton communities were sampled in both lakes before (pre-drawdown), during (low water), and after (post-drawdown) the artificial drawdown procedure. In LPB, drawdown resulted in an increase in zooplankton density, and temporarily changed the community in association with an increase in water conductivity and presence of non-planktonic organisms during the low water phase. In LG, drawdown had no significant effect on zooplankton community between the phases before and during the drawdown event. The results from this study suggest that artificial drawdown over a short timeframe in reservoir systems do not negatively affect the overall density, richness, and diversity of zooplankton communities in marginal shallow lakes.