Southeast Coast Of India Research Articles

Microplastics pollution in tropical estuary (Muttukadu Backwater), Southeast Coast of India: Occurrence, distribution characteristics, potential sources and ecological risk assessment

Around the world, microplastic pollution is pervasive and is regarded as the biggest threat to all ecosystems. We conducted the present study to determine the prevalence of microplastics (MPs), their polymer hazard risk (PHI), and any potential sources of these particles in the estuary of Muttukadu Backwater, Southeast Coast of India. Microplastics were extricated from surface water and sediment by the wet peroxide method, identified by a stereo zoom microscope (SM), and characterized by ATR-FTIR and SEM-EDS analysis. The average microplastic abundance in sediment and surface water was 815±158 particles Kg−1 and 195±38 particles m−3, respectively. The most common microplastics based on shapes were fibers and fragments in both sediment and surface water, with blue and green-colored microplastics being the most frequently observed colors. Type II polymer particles (<3.00 mm–1.00 mm) are dominant particles in sediment (36 %), and type I (5.00 mm–3.00 mm) particles dominate in surface water samples (49 %). Energy dispersive X-ray spectrometer (EDS) results showed that the following chemical elements, such as O, C, Cl, Fe, Na, Al, K, Ca, and Si, as well as the order of the trace metal Pb > Cr > Ni > Co > As > Cu > Cd > Zn, are observed by microplastics of all sediment sampling location. The pollution load index (PI), polymer hazard index (PHI), and potential ecological risk (PER) index models revealed varying level of risk. The polymer hazard index (PHI) reveals that both water and sediments are moderate to highly MP contamination. The hazards of polymers such as polyethylene, polystyrene, polyester, and polyamide significantly contributed to hazard level IV. Inadequate plastic waste management, human habitation and tourism, rapid industrialization, and coastal construction are the main sources of microplastic contamination in the study area. The proper guidelines, potential policies, and technological interventions are much needed to reduce the microplastic contamination along Southeast Coast of India.

Gillnet Selectivity for the Coromandel Flying Fish, Hirundichthys coromandelensis (Hornell, 1923), along the Nagapattinam Coast, Southeast Coast of India

Gillnet Selectivity for the Coromandel Flying Fish, Hirundichthys coromandelensis (Hornell, 1923), along the Nagapattinam Coast, Southeast Coast of India

Coral recruitment assessment as a pre-requisite experiment to restore shallow water coral communities of Palk Bay, southeast coast of India

Coral recruitment assessment as a pre-requisite experiment to restore shallow water coral communities of Palk Bay, southeast coast of India

Comparison of catch efficiency of wire mesh fish traps operated along the coast of Thoothukudi, South-east coast of India

Aim: The study designs and fabricates traps with diverse wire mesh colors and shapes for field experiments. It also collects detailed catch data to assess their catch efficiency and determine the most effective design. Methodology: Experimental fish traps were fabricated utilizing four distinct colors (Light green, Dark green, White and Orange) and three different shapes (rectangle, square and circle). Fishing trials were conducted in selected fishing villages of Thereshpuram, with the traps operated fortnightly from June 2022 to May 2023. The catch rate per trip (CPUE) was calculated using the Total catch (in numbers) divided by the Unit Effort (White, 1987). An economic analysis of trap fishery was also performed based on gross revenue and total cost (Geetha et al., 2014). Results: The traps' overall catch per unit effort (CPUE) was recorded at 0.48Nos hr-1. Siganus canaliculatus emerged as the dominant species among the fishes trapped, constituting 16% of the total catch. Regarding trap color, the highest CPUE was observed with traps of dark green color (0.63 Nos hr-1), followed by light green (0.51 Nos hr-1), white (0.49 Nos hr-1) and orange (0.38 Nos hr-1). Economically, the performance of the trap fishery was evaluated using indicators such as operating cost/year, fixed cost, gross revenue and profit cost ratio. The success of the trap fishery was further emphasized by a benefit-cost ratio (BCR) of 3.50. Interpretation: Dark green-colored, square-shaped traps show promise in significantly enhancing fishermen's profits due to their higher catch per unit effort (CPUE) compared to other colors. Moreover, dark green traps may offer ecological advantages by blending into natural surroundings. This study highlights their potential and provides practical insights for fishermen to make informed gear choices, considering factors like color and shape. Key words: BCR, Color, CPUE, Shape, Trap

Taxonomy and Distribution of Benthic Foraminiferans in the Selected Group Islands of Gulf of Mannar Marine Biosphere Reserve

The present work deals with the taxonomy and distribution of benthic foraminifera from Gulf of Mannar Marine Biosphere Reserve (GoMBR), South east Coast of India during 2020 – 2023. Sediment samples were collected from Mandapam, Keezhakarai and Vembar group of Islands through standard methodology, A total of 36 species belonging to 20 genera, 16 families and 4 orders. A holistic approach regarding soil texture and physico-chemical properties of soil and water shed more light on the diversity and distribution of foraminifera in GoMBR.

Feeding habits of the longfin goatfish Upeneus supravittatus Uiblein and Heemstra, 2010, along Chennai coast, south India

Recognising the need to understand the feeding habits of marine fishes, a study was undertaken on the longfin goatfish Upeneus supravittatus Uiblein and Heemstra, 2010, which contributed to trawl fisheries along Chennai coast (south-east coast of India). Dataon trophic attributes such as mouth gape area, gill raker counts, stomach and intestine lengths and gut condition and contents were collected and analysed to determine condition index, index of relative importance (IRI), niche breadth and trophic level (TrL) with reference to two variables, namely, body size (small, medium and large) and season (post north-east monsoon (PNE); summer (SUM); south-west monsoon (SW); north-east monsoon (NE). The mouth gape area of U. supravittatus was 129.3 mm2. The maximum body depth-total length ratio was 1:5.0; gill rakers in lower arch was 29 and the relative intestine length was 0.48. Empty stomach contributed 56.1% of the samples. U. supravittatus fed on prey belonging to 25 Orders and &gt;40 Genera. Decapods such as shrimps and crablets were the main prey followed by fishes. The IRI of decapods was 6474 and that of fishes was only 193. The maximum prey size predated by the fish was 33.5 and 9.8% in terms of the predator’s length and weight, respectively. Higher prey diversity was noticed in small size group and during south-west monsoon season. The narrow niche breadth of 0.20 showed the selective nature of the fish to feed on decapods. The fish is a benthic carnivore with a mean trophic level of 3.58. The trophic level decreased with body size. Diet similarity was evident between north-east and post north-east monsoon and between summer and south-west monsoon seasons. Diversity indices showed marginal variation in prey diversity among size groups and among seasons. This study paves way for estimating production efficiency of U. supravittatus. Keywords: Diet composition, Index of relative importance, Trophic level, Trophic morphology, U. supravittatus

Assessment of metal-associated health risk in different trophic levels in tropical estuary on the southeast coast of India

Metal contamination in coastal and marine ecosystems has become a significant global concern due to its hazardous characteristics, environmental persistence, and ability to bioaccumulate in aquatic ecosystems. This poses a serious threat to the environment and the health of humans worldwide. To address these concerns, this study estimated the concentrations of metals in various trophic levels, including phytoplankton, zooplankton, bivalve, and fish. Monthly sampling was carried out in Pondicherry Fishing Harbor (PFH) and Pondicherry Open Sea (POS) between January 2017 and December 2018. The value of Cd, Pb, Cr, Co, Ni, Cu, Zn, and Mn in sediment at the PFH was considerably higher compared to the POS, indicating the impact of human activity there. The contamination factor (CF) for other metals was <0.5, suggesting minor contamination in the Pondicherry coastal sediment, the CF value for Cd was higher at PFH. Comparably, the risk index (RI) at the PFH was likewise greater because of Cd, leading to an overall risk grade of “considerable” at the PFH whereas it was “low” at the POS. The marine pollution index (MPI) showed minimal values in fish regardless of the collection sites, which was calculated based on the values of all metals. The estimated daily intake, target hazard quotient, and hazard index assessed for potential human health risk suggest that the values were within acceptable thresholds for adults and children for fish consumption from POS. However, the direct consumption of bivalve for the long term poses significant non-carcinogenic health risks in both age groups, particularly in children, who are 1.31 times more susceptible than adults. These findings highlight the need to evaluate the presence of metals in the food chain to determine their transfer to the different trophic levels, which can help mitigate the associated risks for sustainable coastal ecosystem management.

Fishery status of the green tiger shrimp (Penaeus semisulcatus) in Palk Bay, in the southeast coast of India: Local and global perspectives

The green tiger shrimp (Penaeus semisulcatus De Haan, 1844), traded as Mandapam flower shrimp internationally, is large-sized shrimp and landed on the coast of Palk Bay, India. This work aimed to describe the status of its fishery and identify challenges for the better management of these resources. The estimated fishery landings of P. semisulcatus in 2022 were 7658 t, with an annual average of 6493 t from 2020 to 2022, contributing to the total penaeid shrimp landings in Palk Bay at 57.6%. The economic value of this fishery was estimated to be around $53 million USDs annually (1 USD = 83.16 INR). Between 2007 and 2022, there was a significant difference between green tiger shrimp and total penaeid shrimp landings in Palk Bay across gears and years. All shrimp from Palk Bay have export markets to Japan, the USA, China, and European countries. The average annual export of P. semisulcatus (2015-16 to 2022–23) was 3532 t ($30.9 million USDs). In 2022–23, the USA was the biggest importer of frozen shrimp, followed by China, the European countries, Southeast Asia, Japan, and the Middle-East countries. We formulated a policy guidelines framework for the management and co-management of the green tiger shrimp fishery in Palk Bay based on a precautionary approach.

Dissolved and particulate phase phthalic acid esters in urban, suburban, and rural riverine catchments along the southeast coast of India after the COVID-19 pandemic

Dumped waste plastics have been evidenced as a potential source for harmful chemicals along the riverine regions of India. Furthermore, Corona Virus Disease – 19 (COVID-19) pandemic resulted in a subsequent surge in the use of personal protective equipment (PPE) related single-use plastics and Tamil Nadu was India's second major waste generator. Given the newer challenges from dumped waste plastics along the four major rivers of Tamil Nadu emptying into the Bay of Bengal, we investigated thirteen phthalic acid esters (PAEs), in both dissolved and particulate phases of river water and drinking water samples. Ʃ13PAEs in both phases followed the urban > suburban > rural catchment trend. Di (2-ethyl hexyl) phthalate (DEHP) was ubiquitous in both phases and the sites having a prevalence of open burning activities in the urban catchment showed elevated levels. The suburban and rural catchments of the Kaveri River (KR) and Thamirabharani River (TR) were predominated by DEP and DEHP. It is noteworthy that in the urban catchment, Ln (DiBP) and dissolved organic carbon (Ln DOC), were strongly correlated (R2 = 0.894, p < 0.05). Furthermore, a significant increase of DiBP (p < 0.05) in the urban catchment after the second phase of the pandemic most likely resulted from the wide use of DiBP in PPE plastics. Community-stored water from urban catchment was found to have a maximum of ∑13PAEs up to 3769.38 ng/L in the dissolved phase with elevated DMP concentrations leading to higher estrogenic equivalent. The average daily intake for dissolved phase PAEs was below the USEPA-recommended limit for drinking water. However, prolonged exposure to heavier PAEs in particulate matter cannot be ignored. Estimated ecotoxicological risk assessment showed the highest risk for fish species due to DEHP.

Deformities in Litopenaeus vannamei caused by infectious hypodermal and hematopoietic necrosis viral (IHHNV) infection in intensive grow-out ponds of South east coast of India

Deformities in <i>Litopenaeus vannamei</i> caused by infectious hypodermal and hematopoietic necrosis viral (IHHNV) infection in intensive grow-out ponds of South east coast of India

Study of Seasonal Variations in the Physical-chemical Features of the Cauvery Estuary, Southeast Coast of India

Water is a vital element of the environment, supporting life on Earth and being necessary for all living creatures to live. Between rivers and the ocean, estuaries are places with distinctive ecological traits, an abundance of flora and fauna, and a crucial role in hydrological processes and biodiversity. The biological and physico-chemical aspects of aquatic habitats are intertwined. Investigating seasonal fluctuations in the physico-chemical characterisation of the east coast Cauvery estuary in Tamil Nadu is the goal of the current study. The Cauvery Estuary’s physical and chemical properties are known and have an effect on the estuary. Seasonal fluctuations in the climatic and physico-chemical parameters pH, DO, ammonium, nitrate, BOD, sodium, chloride, sulfate, and fluoride content were noted in the waters of the Cauvery estuary. In the future, research on the ecology, biodiversity, and cultural aspects of the estuary species, as well as the determination of the permissible limit for fisheries and aquatic life, may benefit greatly from the initial data on the physical and chemical properties of the Cauvery estuary. In order to protect the Cauvery Estuary, conservation initiatives are started in collaboration with local non-governmental organizations after a thorough understanding of the various factors influencing these ecosystems is obtained.

Spatio-temporal Distribution of Portunid Crabs within the Gulf of Mannar, Southeast Coast of India

Spatio-temporal Distribution of Portunid Crabs within the Gulf of Mannar, Southeast Coast of India

Activity and Identification of Culturable Methanotrophs from Mangrove Sediments, South East Coast of India

Anthropogenic activities have escalated CH4 emissions, exacerbating global warming, yet specialized bacteria known as Methanotrophs play a key role in mitigating atmospheric CH4 levels by consuming 30-70% of emitted methane. This study focuses on exploring the culturable methanotrophic population within Muthukuda mangrove sediments, an unexplored reservoir of methanotrophic diversity. The sediment sample yielded a methanotrophic bacterial count of 1.5 x 103 CFU/g, leading to the selection of three unique bacterial morphotypes (NCT270, NCT271, and NCT272) for in-depth investigation. Optimal growth was observed at pH 8, with peak growth at 30°C, while extreme temperatures of 4°C and 40°C inhibited growth across all isolates. Salinity levels between 20 and 30 ppt supported optimal growth, with strains displaying tolerance to various stressors. Methane served as the sole carbon source for all experiments, with positive urease production noted after 7 days of incubation. Microscopic and biochemical analyses suggested the classification of strains NCT270, NCT271, and NCT272 within Group I methanotrophic genera: Methylomicrobium, Methyloscarcina, and Methylomonas, respectively. BLASTn analysis of 16S rRNA gene sequences shared high similarities with known methanotrophic species Methyloscarcina fibrate (ON834586) with 99.28%, Methylomicrobium album (ON834587) with 98.77% and Methylomonas methanica (ON834588) with 99.15%. The resulting insights enhance our understanding of culturable methanotrophic diversity and underscore its potential for environmental applications.

Identifying seawater interaction with coastal aquifers using hydrochemical and GIS for Nagapattinam district, southeast coast of India

Groundwater chemistry of the two different seasons collected between 2020–2021 from the coastal areas of Nagapattinam, Mayiladuthurai and Karaikal in Tamil Nadu state of southeast India were evaluated for seawater intrusion into coastal aquifers. Groundwater types, its classification was evaluated to know the extension of seawater intrusions into coastal aquifers using the Groundwater Quality Indices (GQI) such as GQIPiper(mix), GQIPiper(dom), fsea, GQIfsea and GQISWI. Piper diagram grouped most samples (GQIPiper(mix) and GQIPiper(dom)) in domain-II, representing Na-Cl water type, followed by domain-IV, indicating mixed Ca-Mg-Cl water for both the seasons. As measured by the saltwater Intrusion as Groundwater Quality Index (GQISWI), about 62.5 % and 37.5 % of the pre-monsoon samples showed low saltwater intrusion and moderate seawater intrusion, respectively. In the post-monsoon samples, the low saltwater intrusion increased to around 82.5 % and the moderate seawater intrusion decreased to 17.5 % of the groundwater samples. The GIS framework was used to display the geographical distribution of groundwater types as well as the delineation of vulnerable zones from seawater intrusion.

First record of Leodice uschakovi (Wu, Sun &amp;amp; Liu, 2013) (Eunicidae, Polychaete) in Gulf of Mannar, southeast coast of India

First record of Leodice uschakovi (Wu, Sun &amp;amp; Liu, 2013) (Eunicidae, Polychaete) in Gulf of Mannar, southeast coast of India

Assessing the Ecological Quality Status in tropical Indian estuaries: testing the applicability of benthic foraminiferal indices.

The ecological quality status (EcoQS) of Vellar and Uppanar estuaries (Southeast coast of India) has been monitored monthly, using a combination of foraminiferal (Foram Stress Index: FSI and exp(H'bc) indices and abiotic (Pollution Load Index: PLI, Dissolved Oxygen: DO, and Total Organic Carbon: TOC) parameters. The Uppanar Estuary shows relatively higher values of PLI and TOC and lower DO values than Vellar Estuary. The highest value of TOC and PLI are recorded during the monsoon season. These variations are well mirrored by the change in exp(H'bc) and FSI. The lowest values of exp(H'bc) are observed with the monsoon season and could be ascribed by an overall reduction of salinity, and to the highest level of TOC and PLI in response to enhanced river discharge. The FSI also exhibits great variability with significant higher values in the Vellar Estuary than in the Uppanar Estuary. The EcoQS evaluated by a combination of pollution- (i.e., PLI, TOC and DO) and foraminiferal-based [i.e., FSI and exp(H'bc)] indices are highly consistent (73.4%). The most frequent disagreement among indices is mostly associated to Uppanar Estuary and, particularly, in the inner stations. This difference might be related to a time-lag response of benthic foraminifera in terms of diversity and assemblages' compositions as well as of the pollution indicators in response to enhanced riverine input. This study further supports the application of foraminiferal-based indices in EcoQS assessment in transitional environments including tropical Indian estuaries. It also fills the gap of knowledge by providing a seasonal perspective on the variation of EcoQS based on a monthly-scale sampling.

Sediment distribution and transport pattern in the nearshore region, southeast coast of India

The present paper aimed to assess the sediment distribution pattern, mode of transport, and its interaction with hydrodynamic and topographic conditions at different depths and regions along the east coast of India. About 900 surficial sediment samples were collected and analysed on a monthly basis for the Chennai coastal region at 32 stations from 2013 to 2015. The study region is classified into four types, such as beach, inlet, 5 m, and 10 m depth. Sediment textural and grain size trend analyses were conducted to achieve the objectives. Sediment characteristics for the region were recorded as sandy, equally dominated by unimodal and bimodal at the beach, while unimodal at shallow depths (5 and 15 m). The sediments were medium sand to coarse sand at the beach, mostly fine followed by medium at 5 and 15 m depths. The sediment sorting is dominated by moderately well-sorted sediments; the skewness of beach sediments was negative, while nearshore sediments were found positive; average kurtosis values of sediments were noticed to be mesokurtic. The CM plot depicts that the sediments were mostly derived by tractive current, and the modes of transport are “bottom suspension and rolling” and “graded suspension no rolling” at beach locations and shallow water depths, respectively. The GSTA analysis reveals the annual average sediment transport pattern is northerly. The numerical hydrodynamic study confirms the GSTA and CM plot analysis. The study reveals a stable sedimentary environment south of the Chennai port and instability in the northern part. The study includes large spatiotemporal nearshore sediment data with hydrodynamic conditions, immensely helpful to coastal stakeholders and researchers.

Abundance, distribution and characterization of microplastics in Tropical River Estuary, South East Coast of India

Abundance, distribution and characterization of microplastics in Tropical River Estuary, South East Coast of India

Influence of seasons and environmental variables on methane dynamics in the Muthukuda Mangrove sediments of Tamil Nadu

Aim: In order to understand the methane biochemistry in the Muthukuda mangrove ecosystem, this study aimed to report on methane production, oxidation, flux, and also to investigate the effect of seasons and environmental variables on methane dynamics. Methodology: Sediment analysis was carried out monthly for a year (2021-2022) from the Muthukuda mangrove, south-east coast of India, which is an unexplored region in terms of methane dynamics. Methane parameters methane concentration, methane oxidation, methane production and methanotrophic enumeration were analysed from the sediment samples collected by a PVC corer from the study site. The methane parameters were analysed using standard methods by gas chromatography. The physiological parameters were analysed on the site using portable probes. Results: The physio-chemical parameters varied with the changing seasons at different depths. The concentrations of organic parameters were higher for carbohydrates, followed by lipids and proteins. LOM was higher in the surface and mid sediments in all the seasons. The concentration of methane was higher during summer in surface sediments. Generally, higher methane oxidation was observed in the mid and bottom sediments during all the seasons. Methanotrophic enumeration ranged from 0.4 ±0.7 to 4.8±2.4 x108 g-1. Interpretation: The results suggest that the bacterial community was involved in both methane oxidation and production, though oxidation of methane was lesser than production contributing to the atmospheric methane, methanotrophic bacteria which oxidizes methane significantly playing a major role in the regulation of methane flux. Key words: Methane oxidation, Methanotrophs, Muthukuda mangrove

First record of plastiglomerates, pyroplastics and plasticrusts along the beaches of Tamilnadu, Southeast coast of India

Plastic litter affects coastal and marine ecosystems globally. This study represents the first record of pyroplastics and plasticrust in the beaches of Tamil Nadu, India. All samples were FTIR spectroscopically examined to confirm the polymer composition of the suspected plastics. The 16 plastic formations were found in TamilNadu, including six plastiglomerates nine pyroplastics and one plasticrust. Five types of polymers (PET, PP, PVC, PA, and PE) were found on the plastic matrices. The study also revealed that pyroplastics and plasticrust formed by degradation of plastics through weathering in the coastal environment. The present study also found that four types of marine fouling organisms such as oyster larvae, bryozoan, barnacle and polychaete worm were encrusted on the two pyroplastics. The emergence of these new forms of plastic raises concerns about their interactions with the environment and biota.