Vijay Kumar Deepak Samuel

This study highlights the impact of urbanization, agricultural runoff, and invasive species on freshwater ecosystems and aquatic biodiversity. It presents a comparative ecological assessment of two freshwater lakes in Vellore District, Tamil Nadu, India: Katpadi Lake (urban) and Saina Palayam Lake (rural). A total of 15 fish species were documented across both lakes, with Oreochromis niloticus identified as an exotic invasive species. The fish community was dominated by Cypriniformes (60%), demonstrating ecological adaptability. Diversity indices such as Shannon (H′) and Simpson (1–D) showed slight variations between the lakes. Katpadi Lake had higher total dissolved solids and conductivity, indicating greater anthropogenic influence. Ten macrophyte species, including submerged, floating-leaved, and emergent types, were observed, with their distribution differing between urban and rural sites, reflecting habitat and water-quality differences. Macrophyte diversity was greater in Saina Palayam Lake, linking habitat complexity to higher fish diversity. Submerged species such as Najas marina and Myriophyllum spicatum likely enhance habitat quality for native species. The rural wetland recorded nitrate and phosphate concentrations of 3 mg L−1 and 0.13 mg L−1, respectively, indicating measurable nutrient enrichment, while higher hardness, chloride, and ammonia levels in Katpadi Lake point to urban pollution. The findings underscore the importance of integrated monitoring of fish, macrophytes, and water quality to conserve and manage freshwater biodiversity across different environmental contexts.

Fish diversity in relation to macrophyte distribution and physicochemical parameters was studied across six wetlands in Vellore District, Tamil Nadu, India. A total of 20 fish species were recorded, of which 12 are native to India with a higher prevalence in rural wetlands. Urban wetlands exhibit lower relative diversity due to the dominance of Oreochromis niloticus and the presence of Clarias gariepinus which may pose threats to native fish populations. Macrophytes, which influence fish habitat and growth, are abundant in both urban and rural sites. Of the 20 macrophytes identified, 14 are native to India. Physicochemical parameters show variations across sites, yet Canonical Correspondence Analysis indicates a positive correlation between environmental factors and fish diversity. These findings highlight the importance of habitat conditions in maintaining fish diversity and emphasize the need for conservation strategies to protect declining native fish species in urban wetlands.

Seagrasses are critical coastal ecosystems that provide multiple ecosystem services but are increasingly threatened worldwide. Effective monitoring is essential for detecting habitat change and supporting conservation efforts. Although multi-metric indices offer holistic ecosystem assessment, such tools remain limited for tropical multispecies seagrass meadows. This study developed a Seagrass Health Index (SHI) to assess seagrass health in Pulicat Lagoon. From 37 initial variables, 12 key indicators were selected and grouped into six sub-indices: ecosystem structure, soil characteristics, sediment heavy metals, sediment nutrients, water nutrients, and water quality. The SHI was validated through sensitivity analysis, internal consistency testing, and correlation with seagrass cover. Results indicated overall excellent seagrass health in the lagoon (SHI = 2.04), with the north zone classified as excellent (SHI = 2.69) and the south zone as good (SHI = 0.58). The study demonstrates the value of field-based ecological assessments for dynamic coastal systems and provides a baseline framework that could be adaptable for other tropical seagrass ecosystems following further validation across diverse environmental settings.

The present study reports the first zoogeographical record of the squat lobster Munidopsis lauensis Baba and de Saint Laurent, 1992 from a cold-seep site in the Krishna-Godavari Basin (Bay of Bengal), Northern Indian Ocean. Molecular analysis of the partial mitochondrial gene coding for cytochrome C oxidase subunit I (COI mtDNA), and mitochondrial 16S ribosomal RNA (16S rRNA) validated its identity. The present observation extends its geographical distribution to the Northern Indian Ocean. Additionally, molecular barcodes (COI) were generated for Munidopsis scobina Alcock, 1894, Munidopsis wardeni Anderson, 1896, and Shinkaia crosnieri Baba and Williams, 1998 collected from the Indian Exclusive Economic Zone.

Our study documents the outbreak of a coral-killing sponge Terpios hoshinota in the coral reefs of Lakshadweep archipelago and highlights that it has further extended its territory into the isolated atolls of Arabian Sea and maybe a growing threat to the existing coral reefs in the region.

An emphasis on sustainable marine fish production has paved the way for the enactment of Marine Fisheries Regulation Acts and subsequent regulations in India. A closed season ban on fishing has been one of the very few successful regulatory measures since its introduction in 2001 in Tamil Nadu. Since 2017, the fishing ban period has been extended from 45 to 60 days for the east coast of India, for ecosystem‐based marine fisheries management. This study analyses the socioeconomic impacts of change in the fishing ban (closed season) across the four coastal zones of Tamil Nadu. For the past 10 years, CPUE has been stable or increased marginally. Among the four coasts, the relative change in employment and labour income loss was highest for Palk Bay (36.84%). Transaction costs of implementation of the ban caused an additional expense of Rs 496.5 million to the Government in 2017 and the overall total labour income loss has leaped from Rs 1,638.2 to 2,100.2 million due to the extension of the ban. The fishing ban has aided in the recovery of habitat and regeneration of stock through recruitment. Training and capacity building on alternative livelihood options are highly recommended to enable the workers to cope with the ban period.