Explore the vast range of titles available.

Vasanth, K.; Muthupandi, K.; Naganandhini, V.; Radhakrishnan, K., and Narayanan, M., 2025. Length-weight relationships of eight pelagic fish species caught by drift longlines in the Gulf of Mannar, India. Journal of Coastal Research, 41(3), 510–515. Charlotte (North Carolina), ISSN 0749-0208. The length-weight relationships were estimated for eight pelagic species caught in the Gulf of Mannar, India, using experimental longlines. The experimental study was conducted from January to October 2022 in fortnightly intervals using longlines (3000 m for needlefish and 11,250 m for carangids), each equipped with 600 “J”-type fishing hooks of various types (straight, reversed, kirbed). The hook numbers used were standard sizes that ranged from 8 to 11 for both groups (needlefish and carangids). The longlines were fabricated with polyamide monofilament and operated from 1 to 2 m depth for needlefish and 20 to 25 m depth for carangids for 3 to 5 hours for both longline units. Overall, 21,150 hooks were deployed in 24 fishing trials for each experimental longline. A maximum total length was recorded for four needlefish species, Strongylura strongylura (80), Tylosurus choram (91), Tylosurus crocodilus (97), and Ablennes hians (96), and four carangids species, Caranx bajad (60.5), Alectis indicus (62), Caranx ignoblis (69), and Scomberomorus commerson (74). In terms of growth, the length-weight relationships revealed positive allometric growth (b >3) for three species of carangids, C. bajad, S. commerson, and A. indicus (p < 0.05) and negative allometric growth (b <3) for four species of needlefishes, T. choram, S. strongylura, T. crocodilus, and A. hians, and one species of carangid, C. ignoblis.

Sahu, A.; Venkataramani, V.K.; Chandravanshi, S., and Chandran, S., 2024. Spatio-temporal distribution of portunid crabs within the Gulf of Mannar, southeast coast of India. Journal of Coastal Research, 40(5), 937–951. Charlotte (North Carolina), ISSN 0749-0208. To explore the variety of portunid crabs along the Gulf of Mannar coast, an intensive survey was conducted for 1 year from October 2021 to September 2022. The sampling was done biweekly, at four landing sites, i.e., Vedalai, Keelakarai, Therespuram, and Thiruchendur. The Gulf of Mannar has a rich diversity of portunid crabs, and bottom set gillnets are the primary method of capture. Twenty-seven species were recorded in the study area, representing five genera. The genus Charybdis recorded the highest number of species with 11 species, followed by the genus Portunus and the genus Thalamita with eight and four species, respectively. The genus Scylla and the genus Podophthalmus were represented by three and one species, respectively. To conduct the biodiversity assessment, the occurrence and abundance data of portunid crabs were collected for 12 months in all the selected landing centers in the Gulf of Mannar. The data collected were pooled together by month, station and season, which included summer (March-May); pre-monsoon (June-August); monsoon (September-November) and post- monsoon (December-February). From the collected occurrence and abundance data, 15 biodiversity indices were calculated using the PRIMER v7 computer software package.

A pink-coloured, salt- and alkali-tolerant strain, JC639 T , was isolated from a specimen of the marine sponge Spheciospongia sp. The novel isolate is motile, aerobic and forms oval to pear-shaped cells. It shares the highest 16S rRNA gene sequence identity with Stieleria neptunia Enr13 T and Stieleria maiorica Mal15 T in the family Pirellulaceae (phylum Planctomycetota ). Optimum pH and temperature for growth are 8.0 (range 7.0–10.0) and 25 °C (range 10–30 °C), respectively. Major fatty acids are C 15:1 ω8c, C 16:0, C 18:1 ω9c, C 18:0 , and C 16:1 ω7c/C 16:1 ω6c. Major polar lipids are phosphatidylcholine and phosphatidylethanolamine. The genome of strain JC639 T has a size of 9.56 Mb and a DNA G + C content of 59.5%. The polyphasic analysis of the isolate supports its delineation from the known species in the genus Stieleria . We therefore introduce Stieleria mannarensis sp. nov., represented by JC639 T (= KCTC 72168 T  = NBRC 113878 T ) as the type strain. Based on an analysis of established phylogenomic markers performed with all current members of the overlapping genera Stieleria and Roseiconus , we further propose to include the two so far characterized Roseiconus species in the genus Stieleria .

The status of reefs in Palk Bay and the Gulf of Mannar was studied during April–May 2016 following a bleach alert, as the sea surface temperature recorded a sudden increase from 30.5°C to 34.0°C in Gulf of Mannar. About 71.48% ± 8.9% of the corals in Palk Bay and 46.04% ± 3.78% in Thoothukkudi group of Islands in Gulf of Mannar were found bleached, showing a clearly decreasing trend from north to south, which could be attributed to the corresponding pattern in intensity of SST recorded in the study sites. Observations of bleaching patterns among different life-forms showed 68% of the bleached corals were massive forms. It was observed that 22 out of the 26 massive forms were bleached, while the Acropora corymbose (ACC), digitate (ACD) and encrusting coral (CE) forms were not bleached in any of the study sites in Palk Bay and Gulf of Mannar. The study suggests that the ACC, ACD and CE forms have adapted to thermal stress, subsequent to the earlier mass bleaching events. The study highlights the need for understanding the molecular mechanism of the association between corals and the symbiotic algae, for further understanding on coral bleaching in Indian waters.

We used a 12-yr data set of benthic cover (2005–2017), spanning two bleaching events, to assess changes in benthic cover and coral community composition along 21 islands within Gulf of Mannar (GoM), southeast India. Overall, between 2005 and 2017 reefs had a simultaneous decrease in relative coral cover (avg. =  − 36%) and increase in algal cover (avg. =  + 45%). Changes in benthic cover were not consistent among islands, ranging from − 34 to + 5% for coral cover and from − 0.3 to + 50% for algae. There was a spatial gradient in coral mortality, which increased among islands from west to east. However, there was a disconnect between coral loss and subsequent increases in algae. Algal cover increased more on islands in west GoM where coral loss was minimal. Environmental co-factors (coral cover, percent bleaching, degree heating weeks, fish densities, Chl-a, pollution) explained > 50% of the benthic cover responses to successive bleaching. Coral survival was favored on islands with higher fish densities and chlorophyll-a levels, and increases in algal cover were associated with higher measures of pollution from terrestrial runoff. Coral morphotypes differed in their response following successive bleaching resulting in changes in the relative abundance of different coral morphotypes. Existing climate projections (RCP8.5) indicate a 22-yr gap in the onset of annual severe bleaching (ASB) for reefs in the east versus west GoM, and ASB was ameliorated for all reefs under the RCP4.5 projections. There is limited knowledge of the resilience of GoM reefs, and this study identifies coral morphotypes and reefs that are most likely to recover or decline from successive bleaching, in the context of forecasts of the frequency of future bleaching events in GoM.

Background The biosynthesis of metal nanoparticles by marine resources is thought to be clean, nontoxic, and environmentally acceptable “green procedures”. Marine ecosystems are very important for the overall health of both marine and terrestrial environments. The use of natural sources like Marine biological resources essential for nanotechnology. Seaweeds constitute one of the commercially important marine living renewable resources. Seaweeds such as green Caulerpa peltata , red Hypnea Valencia and brown Sargassum myriocystum were used for synthesis of Zinc oxide nanoparticles. Result The preliminary screening of physico-chemical parameters such as concentration of metals, concentration of seaweed extract, temperature, pH and reaction time revealed that one seaweed S. myriocystum were able to synthesize zinc oxide nanoparticles. It was confirmed through the, initial colour change of the reaction mixture and UV visible spectrophotometer. The extracellular biosynthesized clear zinc oxide nanoparticles size 36 nm through characterization technique such as DLS, AFM, SEM –EDX, TEM, XRD and FTIR. The biosynthesized ZnO nanoparticles are effective antibacterial agents against Gram-positive than the Gram-negative bacteria. Conclusion Based on the FTIR results, fucoidan water soluble pigments present in S. myriocystum leaf extract is responsible for reduction and stabilization of zinc oxide nanoparticles. by this approach are quite stable and no visible changes were observed even after 6 months. These soluble elements could have acted as both reduction and stabilizing agents preventing the aggregation of nanoparticles in solution, extracellular biological synthesis of zinc oxide nanoparticles of size 36 nm.

The present study analyzed diversity, prepared a checklist and assessed molluscan biodiversity (gastropods and bivalves) associated with the mangrove ecosystem of the Thoothukudi coast, Gulf of Mannar, Southeast coast of India. Molluscan specimens were hand-picked fortnightly from three mangrove sampling stations (Thoothukudi, Palayakayal, and Punnakayal) along the Thoothukudi coast from December 2022 to November 2023. The investigation revealed 87 molluscs species recorded in the Thoothukudi mangroves, including 48 gastropods (7 orders, 17 families, and 34 genera, with Caenogastropoda (19 species) and Neogastropoda (9 species) being dominant. Notably, Euchleus asper was the sole species under order Segueniida) and 39 bivalves (6 orders, 12 families, and 33 genera, with Venerida (12 species) as the dominant order) among the gastropod Caenogastropoda and Neogastropoda were the dominant, while Venerida was the most prevalent bivalve in the Thoothukudi mangroves. This study highlights the crucial role of mangroves and its associated organism like gastropod and bivalves in supporting the mangrove ecosystem in species richness and which maintaining coastal biodiversity. Based on the Shannon-Weiner index (Shannn, 1948), the species richness indicates a healthy, stable condition of the ecosystem. The checklist provides a baseline for future monitoring and conservation, aiding protection strategies against anthropogenic impacts. This study suggests monitoring mangroves and their faunal biodiversity to maintain the sustained health of the ecosystem.

Coastal waters are dynamic because of anthropogenic activities that contribute nutrients and contaminants. These changes have the potential to alter patterns of primary production and thus pelagic food webs. Here, we investigated the spatial variation of the phytoplankton community and its response to changing environmental variables at 84 stations along the five coastal districts of Tamil Nadu (TN). During the present study, 85 phytoplankton species were recorded, such as diatoms (64), dinoflagellates (18), silicoflagellates (1), and Cyanophyceae (2). The maximum phytoplankton abundance was recorded on the Thanjavur coast and gradually decreased towards the south coast of Tamil Nadu. Among the phytoplankton community, 50% was dominated by pennate diatoms, attributed to higher NO 3 − concentrations in the coastal waters due to agricultural discharge. Cluster analysis revealed that Ramanathapuram and Tirunelveli formed a closed cluster, whereas Thanjavur and Pudukottai formed a separate closed cluster associated with higher nutrient and metal concentrations, highlighting the difference in physicochemical parameters between the northern and southern districts of the TN coast. Relatively high nutrient concentrations in the coastal waters of northern districts are of greater concern, which could impact the coastal ecosystem. Coastal eutrophication is becoming a widespread phenomenon, causing disruption in the food chain and ecosystem balances and hence requiring regular monitoring and management.

Aim: Considering the potential harm caused by plastic pollution to the marine ecosystem, the present study was conducted to elucidate the status of microfiber and macrolitter in the selected areas of Thoothukudi on the South-east coast of India. Methodology: The abundance and distribution of subsurface microfibers in four locations of Tuticorin inshore waters were estimated by filtering subsurface waters using a 250µm mesh epineuston net. The non-biodegradable macrolitter on the seabed at three locations of Thoothukudi was estimated by swept area method. Results: Among the four selected stations, a higher quantity of microfibres was observed in the subsurface waters at 5m depth close to nearshore areas, with the highest mean numerical abundance of 3.13±0.3 nos.m l-1. The annual difference in the subsurface microfibre abundance varied significantly between stations (p<0.05). Plastics were the most dominant litter constituents on the sea beds among three stations. A significant seasonal variation (p<0.05) with maximum mean total macrolitter abundance was noticed on the seabed at Kayalpattinam (45.81± 9.3 kg km-2). The estimated mean macrolitter abundance at all the stations was higher than the reported national average of 10.95±3.05 kg km-2. Interpretation: This study revealed variations in the abundance and distribution of microfibers and macrolitters in the selected areas of Tuticorin. The study emphasises the role of land and marine-based anthropogenic activities in the plastic pollution of this region. Key words: Abundance, Gulf of mannar, Microfibres, Macrolitter, Subsurface waters, Seabed