Planktonic Microcrustacean Community Structure Varies with Trophic Status and Environmental Variables in Tropical Shallow Lakes in Malaysia

A study was conducted to evaluate planktonic microcrustacean species composition, abundance, and diversity in lakes with different trophic status and to determine the relationship between microcrustacean community structure and lake environmental conditions. This study hypothesized that there are correlations between eutrophication levels and microcrustacean community structures in a lake. Three shallow lakes of different trophic status (Sembrong, Putrajaya and Subang lakes) were selected for this study. Two-Way Analysis of similarities (ANOSIM) revealed differences in microcrustacean diversity and density amongst lakes, where the hypereutrophic condition in Sembrong lake resulted in the lowest diversity but the highest density of microcrustaceans. Similarity percentage (SIMPER) analysis identified the discriminator species among lakes where the domination of small-sized microcrustaceans was observed in lakes with high levels of eutrophication; the hypereutrophic Sembrong lake (Ceriodaphnia cornuta, 74.0%); the meso-eutrophic Putrajaya lake (Bosmina longirostris, 46.9%; C. cornuta, 19.4%). Chlorophyll a, total phosphorus and water transparency showed significant roles in the distribution of microcrustaceans. The canonical correspondence analysis (CCA) scores indicated that small-sized C. cornuta and B. longirostris were related to the eutrophic conditions of lakes. This study elucidated that the lake trophic status could be one of the main factors contributing to the community restructuring of microcrustaceans in tropical lakes.

Phytoplankton diversity in three lakes of South Ural, Russia

Kostryukova AM, Krupnova TG, Mashkova IV, Gavrilkina SV, Nikita O. Egorov NO. 2018. Phytoplankton diversity in threelakes of South Ural, Russia. Biodiversitas 19: 1459-1467. Preservation of water ecosystems in their natural state is of great significance.Phytoplankton is one of the biotic indicators of the lake trophic status and ecological state. This study deals with phytoplankton diversityof three lakes of South Ural, Russia. The studied lakes represented different trophic states: Lake Savelkul was oligo-mesotrophic, LakeIlmenskoe was mesotrophic and Lake Argayash was eutrophic. The species composition of common phytoplankton was recorded inJune-July months during 2015 and 2016. The Cyanophyta (blue-green algae) species were dominant in Lake Ilmenskoe(42-64%) andLake Argayash(55-70%). The Bacillariophyta (diatom algae) species were dominant in the Lake Savelkul(40-66 %). The most commondiversity indices namely the Shannon Index, Simpson Index and Margalef Index were determined and the data was also analysed usinggraphs. The graphs were constructed by the similarity calculating method on the basis of the Sorensen-Czekanowski coefficient.Diversity indices confirm the higher species richness of the microalgal community of Lake Ilmenskoe, classified as mesotrophic. It wasshown that the lakes have sufficiently high biodiversity and high ecosystem resilience. Further, statistical analysis (CCA) revealed thatorthophosphate-phosphorus, nitrite-nitrogen and pH were the most significant environmental factors influencing phytoplanktoncommunity of the lakes studied.

Stocked trout do not significantly affect wood frog populations in boreal foothills lakes

Stocking salmonids into lakes can have negative consequences for some ecosystem components, including amphibians. In the boreal foothills of Alberta, Canada, we compared populations of wood frog ( Lithobates sylvaticus ) at lakes with (n = 5) and without (n = 6) stocked trout over 3 years; all 11 lakes also supported native populations of forage fishes. Abundance and size of adult and young-of-year (YOY) frogs did not differ significantly between stocked and unstocked lakes. We also compared the wood frog population from a twelfth, fishless lake with populations from the 11 fish-bearing lakes (with or without trout); abundance and size of adults and YOY were greater, and YOY emerged earlier in the absence of fish. Based on patterns compiled from a literature review of effects of stocked trout on anuran amphibians, we suggest that characteristics of our study systems, including the presence of native fish, the length of the anuran larval period, lake trophic status, and the existence of complex, littoral habitats, contributed to the lack of major impacts of stocked trout on wood frog populations.