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Water quality is a critical environmental issue, because all forms of life depend on water. The present study focused on the spatiotemporal trends of 22 physicochemical parameters of the water in the Chaliyar River, which originates from the Western Ghats, Kerala, in India, and drains into the Arabian Sea. Water samples were collected from eight stations located along the river in different seasons (pre-monsoon, monsoon and post-monsoon) during two annual cycles (2017 to 2019). Most of the water quality parameters showed significant seasonal variations with spatial heterogeneity. Water quality index (WQI) and comprehensive pollution index (CPI) were used to analyze the river water for its potability and pollution status, respectively. The WQI showed "good" to "unsuitable" category and the CPI showed "sub-clean" to "severely polluted" status at the various stations of the river. The nutrient enrichment of water, analyzed using the trophic state index, showed "mesotrophic" to "high eutrophic" state at various stations, indicating that the river is tending toward eutrophication particularly along the downstream stations. Pearson's correlation demonstrated the influence of natural sources on the riverine water composition. The results of factor analysis revealed that the highest factor loadings were on total hardness, Ca, Mg, chlorinity and salinity, suggesting that non-point inorganic pollution, largely due to river basin geology and salinity ingress, was responsible mainly for potable water quality deterioration. Based on the results, the eight stations along the river were grouped into three clusters of "less," "moderately" and "highly" polluted and recorded a decrease in water quality from upstream to downstream. The study also highlighted the importance of multivariate statistical techniques in identifying the pattern of variability of parameters, besides helping in developing management strategies to improve river water quality by identifying relatively significant parameters causing the maximum water quality degradation. [ABSTRACT FROM AUTHOR]

A comprehensive study on the fish assemblages of the River Cauvery was conducted during 2017–2020 by structured fish sampling surveys, encompassing various sampling sites situated along the upper, middle, lower, and estuarine stretches. The present study recorded a total of 146 fish species belonging to 52 families from the River Cauvery. The highest recorded fish diversity was at Hogenakkal (76 species) as it is situated in the transition zone between Deccan Plateau and the plains of Tamil Nadu. Lowest diversity was recorded at Bhagamandala (23 species), as this site represented a narrow hillstream habitat. As per SIMPER analysis, the silver razor-belly minnow (Salmostoma acinaces) was the most representative species in Upper Cauvery, with percentage similarity contribution (% SC) of 36.55%. The Middle Cauvery situated in the plateau zone was mainly represented by Labeo calbasu (14.01% SC), the exotic Nile tilapia (Oreochromis niloticus) with 8.45%, and the bagrid catfish Mystus cavasius (5.1%). The exotic species contributed to maximum fish catch and gradually replaced the native fish fauna in Lower Cauvery. The fish fauna of Cauvery Estuary is distinct from other zones with a characteristic fish assemblage represented by the glassy perchlet, Ambassis miops (11.97% SC), Crenimugil buchanani (11.14 %), and Mugil cephalus (6.23 %). Among the fish species recorded during the present study, 29 species were endemic to Western Ghats, of which 10 species were categorized as threatened by the IUCN, including 2 critically endangered (Barbodes bovanicus, and Hemibagrus punctatus), 5 endangered (Dawkinsia arulius, Hypselobarbus curmuca, H. mussullah, H. micropogon, and Nemacheilus pulchellus) and 3 vulnerable species (Hypselobarbus kolus, Hyporhamphus xanthopterus, and Wallago attu). A holistic study on the fish communities of Cauvery along the spatio-temporal scale is imperative to ensure sustainable management for conservation of endemic fish fauna. [ABSTRACT FROM AUTHOR]

The present study deals with the description of a new species Sandracottus vijayakumari from Nelliyampathy forest range, southern Western Ghats, Kerala, India with a comparative key of closely related species S. dejeani Aube, 1838. Only one species is known from the genus Sandracottus Sharp, 1882, from southern Western Ghats, Kerala. The Nelliyampathy forest areas are hilly and the altitude of the hills range 40-1,530 m. The region experiences several types of landslides especially during the monsoon (August to September 2018). The new species was discovered in one of the worst landslide hits area in Nelliyampathy forest, Kundrachola region. The new aquatic beetle species is moderately large in size and often very attractively marked dorsally with complex maculations. Additionally, the new species shows a strong synapomorphy along with Eretini, Hydaticini, and Aubehydrini tribes. [ABSTRACT FROM AUTHOR]

This paper deals with the ecology, population size, status of regeneration, habitat degradation and threat status of Elaeocarpus venustus Bedd. an endemic and threatened tree species restricted to Agasthiyamalai Biosphere Reserve, southern Western Ghats, India. The population sites of this species in the study area were recorded using Global Positioning System and mapped using Arc GIS software. The population of this species is highly fragmented due to anthropogenic activities. The total stem count in all population sites from the study area was carried out to understand the population structure. A total of 181 saplings were recorded from the entire study area of which 180 are from a single site. Nearly 64% of the stems recorded in this study are mature stems. Poor regeneration was seen in population sites that were highly disturbed. In spite of good adult population, the low number of saplings shows poor germination of seeds and establishment of seedlings. [ABSTRACT FROM AUTHOR]