Background: Zooplankton biodiversity serves as an ecological indicator of aquatic environment due to their rapid response according to environmental changes. At the present study, impact of seasonal changes on zooplankton biodiversity was conducted in the Ukkadam Lake (Lat 10°59′ N and Long 76°57′ E), at Coimbatore city, Tamil Nadu, India. Results: The biodiversity of zooplankton taxa were studied for a period from December 2011 to November 2012 on seasonal basis. During this time period, in total, 28 species of zooplankton were noticed, which includes 9 species of each Rotifera and Cladocera and 5 species of Copepoda and Ostracoda. In this present observation, total abundance of Rotifera was found to be predominant with 35%, followed by Cladocera 29%, Copepoda 29% and Ostracoda 7%. The population density of various group of zooplankton was observed, and it was found to be following order Rotifera > Copepoda > Cladocera > Ostracoda. The high and low population densities were recorded in summer and early monsoon season respectively. This higher zooplankton population density in summer might be due to the temperature acceleration in the Ukkadam Lake. Conclusions: The present study revealed that zooplankton productivity was found to be higher in the Ukkadam Lake when the temperature was increased in summer season. It indicates that the temperature has influence on the zooplankton diversity. Therefore, increased temperature due to global climate change might have influence on the zooplankton production. Assessment of zooplankton biodiversity will be useful to monitor the health (water quality) and wealth (fishery productivity) of this lake system in the near future.

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This study represents diversity of zooplankton species in a perennial freshwater lake located in Singanallur (Lat. 10.59° N and Long. 77.88° E) at Coimbatore, Tamil Nadu, India for a period of one year (June, 2017-May, 2018. Fifty three zooplankton species including rotifera-18, cladocera-10, copepoda-13 and ostracoda-12 were observed. The first record of an ostracoda species Cypretta campechensis was observed during summer. This species was recognized according to its morphological characteristics of anterior view, posterior view, dorsal margin, lateral view (triangular shape), maxillular palp, posterior seta, posterior claw, uropodal ramus and hemipenis. This was mass cultured in mixed phytoplankton as feed. The molecular identification was done via analysis of the mitochondrial cytochrome c oxidase subunit I (mt-COI). The gene was amplified with universal primers (LCO1490 and HCO2198), sequenced and authenticated with NCBI GenBank (MN641913). The BLAST showed 100% similarity with C. campechensis of Mexico (MF076727). The sequence showed more number of identical amino acid residues than that of variable amino acid sites. The noticed higher AT biases (62.4-63.0%) than GC biases (36.1-37.5%) indicated that lower abundance of nuclear copies of mt-DNA (NUMTs) genes. The divergence rate was very low between the subjected and retrieved species (0.000-0.290%). The endemism of C. campechensis can be used as a bio-indicator of water pollution status of this lake and may afford an opening to assess its importance in aquaculture production.

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Probiotics yield numerous health benefits to the host. In this way the probiotic bacterium, Bacillus coagulans has competitively been excluded the pathogenic bacteria, Streptococcus spp., and Klebsiella spp., from the gut of Macrobrachium rosenbergii postlarvae when given through feed (Manjula et al., 2018). The elimination of these two pathogenic bacteria indicated the fact that B. coagulans improved the disease resistance capacity of M. rosenbergii. The present paper deals with 16S rRNA sequence analysis of gut microbial diversity of M. rosenbergii fed with B. coagulans (CFU, 2.28x10-7) supplemented feed, which revealed the presence of B. coagulans (1541 bp), Lactobacillus fermentum (1516 bp), Lactobacillus lactis (1499 bp), Lactobacillus acidophilus (1507 bp), Escherichia coli (1465 bp) and Staphylococcus aureus (1476 bp). The BLAST of these sequences showed almost 100% similarities with the same species retrieved from the NCBI database. The MAS showed 920 identical amino acids residues, 119 similar amino acids residues and 461 variable amino acids sites. The nucleotide sequence divergence and the calculated phylogenetic information clearly discriminate these bacterial species. Contribution/Originality: This study indicates that the probiotic, Bacillus coagulans used as a feed supplement helped in the exclusion of two pathogenic bacteria Streptococcus spp., and Klebsiella spp., from the gut of Macrobrachium rosenbergii. The gut microflora identified have been barcoded and authenticated.