Metacommunity Concepts Provide New Insights in Explaining Zooplankton Spatial Patterns within Large Floodplain Systems

Flood pulse related physical variables (FLOOD) can affect zooplankton community structure through local factors directly and can also influence through regional dispersal factors of metacommunity concepts indirectly. Therefore, we infer that spatial patterns of zooplankton communities could be related to metacommunity concepts and their importance may depend on the size of the aquatic/terrestrial transition zone (ATTZ). Herein, we explored the relative importance of limnological (LIMNO) and FLOOD variables in zooplankton community by analyzing data from 272 sites across three floodplain lakes in the middle reaches of the Yangtze River. Our results showed that the variation in the zooplankton community can be well explained by the LIMNO and FLOOD variables in all of the lakes under the low water level season. However, during the high water level season, neither LIMNO nor FLOOD can explain the spatial variances of zooplankton. Therefore, our results indicated that testing biogeographical theories and macroecological laws using zooplankton should consider temporal aspects of flood pulse. Furthermore, we noted that the number of explained variance by local variables is negatively correlated with the size of the ATTZ. Metacommunity concepts provide complementary insights in explaining zooplankton spatial patterns within large floodplain systems, which also provide a theoretical basis for ATTZ protection in floodplain management.

Estuarine zooplankton responses to flood pulses and a hypoxic blackwater event

Flood pulses in estuaries following storms and rainfall events, are short-lived but important moments for a range of ecosystem processes including the delivery of resources and promoting productivity. Conversely some flood pulses can lead to adverse outcomes such as poor water quality conditions. The aim of this study was to determine how zooplankton abundance and community composition responded to flood pulses and if they responded differently during a flood pulse that led to hypoxic conditions. To do this we conducted a two-year observational study in the Hunter River estuary, Australia, monitoring zooplankton communities monthly for a period that covered two major flood pulse events including one that caused widespread hypoxia and a major fish kill. The results showed zooplankton abundance was higher or no different following the 2012 flood when dissolved oxygen remained stable compared to pre-flood conditions. During the 2013 flood when hypoxia occurred the abundance of copepods, nauplii and rotifers were at their lowest for the study period. Zooplankton assemblages were not distinctly different following the 2012 flood pulse compared to the pre-flood period but were different during the hypoxic 2013 flood, though quickly returned to resemble pre-flood conditions in the proceeding months. The study provides useful insights in how zooplankton populations may respond to flood events and recover after hypoxic conditions in estuarine ecosystems.

Diversity of vascular plants and zooplankton communities in regard to the ecological assessment of the territory of the ecological park “Samara Venice”, Samara Region, Russia

The results of the floristic and hydrobiological studies performed in May - August 2020 on the territory of the ecological park Samara Venice (Samara Region, Russia) are presented. These data form the basis for the ecological assessment of the territory. The diversity of vascular plants is presented by 4 divisions, 65 families, 205 genera, and 309 species. Among them, 66 species (21.4%) belong to the alien plant species, including nine invasive. Habitats of the plants included in the regional Red List are found. The zooplankton diversity comprises 60 species and morphs. The zooplankton community has undergone significant transformation, manifesting by an increase in the total biomass and in the biomass of crustaceans and rotifers, and by a decrease in absolute and relative species richness. It is revealed that a number of the studied water bodies belong to the transitional type, and may be characterized as of middle position between the meso- to eutrophic type (moderately polluted and polluted waters).

Changes in zooplankton communities of the Lebyazhye system restored lakes

Ponds rehabilitation projects for the purpose of eco - rehabilitation following significant anthropogenic impacts or degradation are becoming more frequent but not always successful. Therefore, the experience of the restoration of the Lebyazhye system lakes in Kazan city (Russia) is interesting. Previously, the lake system used to consist of four ponds, but due to water catchment area reduction, the area of the lake system also decreased, and only one lake remained. The restoration of the Lebyazhye system lakes was carried out in 2017 and included the deepening of the basin of the Bolshoe and Svetloe Lebyazhye lakes to 4 m, the sealing of the bed of future ponds with bentonite mats, supplying water from Izumrudnoye lake through a pressure water conduit and filling the basin of the lakes with water. The research is devoted to the study of the restoration of zooplankton communities in the Lebyazhye system lakes. For this purpose, the indicators of zooplankton communities before and after eco-rehabilitation measures were compared. After the implementation of eco-rehabilitation measures, significant changes in environmental parameters were observed: the salinity of water decreased, the oxygen content in the water, pH increased. In zooplankton communities, the species richness and diversity increased, new species appeared, as well as those that lived in the lake system earlier before eco-rehabilitation measures were taken.

Evaluarea stării comunităților zooplanctonice în condițiile schimbării mediului acvatic

This paper presents research results on the assessment of the status of zooplankton communities under the conditions of changing aquatic environment of the Dniester and Prut Rivers. The current climatic conditions have contributed to the change of the hydrological regime of the investigated ecosystems. The influence on zooplankton was manifested on the one hand by restructuring the species composition and disturbances in quantitative parameters, and on the other hand by increasing the density of zooplankton communities during the study year.

Spatial and seasonal variation of zooplankton assemblages in two tidal control structures in Northeastern Brazil

Zooplankton is a group of organisms that can help to understand the quality of aquatic ecosystems, as they are responsible for transforming energy matter, thus making it available to other links, making them important in aquatic trophodynamics. This study analyzed spatial and temporal variations in zooplankton communities found in two tidal control structures on Ilha do Maranhão, northeastern Brazil. Sampling took place from September 2017 to July 2018. Abiotic parameters (temperature, salinity, and transparency) and plankton samples were recorded monthly throughout the study period at each sampling site. The results found for the abiotic parameters showed a well-defined pattern, with a clear division between the dry and rainy periods. Forty taxa represented the zooplankton community of the São Luís tidal control structure, and from São José de Ribamar by 21 taxa, represented mainly by copepods, ichthyoplankton, foraminifera, polychaetes, and mollusks. The analysis of ecological indices of richness, evenness, and diversity showed a difference in the distribution of organisms among the study areas. We identified an important influence of the physicochemical parameters on the zooplankton communities of São Luís and São José de Ribamar, according to the statistical analyzes used in this study.