Tamil Nadu Coast Research Articles

Screening of Antiviral Efficacy of Few Seaweeds of Tamil Nadu Coast

Lately there has been a lot of interest worldwide in studies on the antiviral activities of marine natural secondary metabolites, notably marine polysaccharides. It has been established that polysaccharides made from marine sources and their derivatives have antiviral effects against potent viruses. Agricultural, biological, food, and pharmaceutical industries all make extensive use of goods obtained from algae. The most well-known chemical components found in algae are polysaccharides, which have been the subject of a variety of studies because of their varied bioactivities. Polysaccharides made from algae have recently risen to the top of pharmaceutical research due to their fascinating antiviral potential. Currently, COVID-19 can be prevented with vaccination, but the brown alga Sargassum wightii has several bioactive compounds that have the following qualities and may be a better option. S. wightii is one of the marine algae species that is rich in sulfated polysaccharides, the secondary metabolites which have antiviral action and the capacity to prevent viral proliferation. Fucoidan, a long-chain sulfated polysaccharide found in various brown algae, has potent antiviral effects. Additionally, sulfated polysaccharides from green algae (such as ulvans) and red algae (such as carrageenan), and lectins from red algae (such as griffithsin) have antiviral therapeutic agents against coronaviruses and other viruses. This research focuses on screening seaweeds for possible antiviral compounds to treat viral infections notably COVID-19.

Assessment of shoreline changes and associated erosion and accretion pattern in coastal watersheds of Tamil Nadu, India

The coastal region is not a constant and depends on several physical elements. Analogous to the world trend, the coastal areas of Tamil Nadu are encountering sea level rise and associated shoreline changes. However, the rate of change is not uniform and varies considerably. The study revealed such differences in shoreline changes during the past 30 years and identified erosion and accretion patterns trends in Tamil Nadu's coastal watersheds, from Pulicat (Thiruvallur district) to Kodyar (Kanyakumari district). The study used remotely sensed Landsat TM (Thematic Mapper) and OLI (Operational Land Imager) datasets to analyse shoreline changes from 1988 to 2018. The Digital Shoreline Analysis System (DSAS) tool is used to derive trends of shoreline changes by End Point Rate (EPR) and Net Shoreline Movement (NSM). The mean EPR is- 0.26 ​m/yr and NSM is-8.03 ​m/yr, suggesting the overall shoreline of the Tamil Nadu coast is shifting landward. However, the annual rates of EPR and NSM vary considerably from watershed to watershed, and therefore, these indices were used to categorise the coastal watersheds based on erosions and accretions. The results identified a high erosion rate in the watersheds of Coleroon, Arasalar (Nagapattinam), Gundar (Ramanathapuram), Vembar, Lower Vaippar (Thoothukkudi), Nambiyar, Hanuma (Tirunelveli), and Putian, Kodyar (Kanyakumari). Field surveys were conducted to verify ground conditions at 139 random locations along the 1000 ​km shoreline stretch. About 75% of respondents said they experience a very high to high risk of coastal erosion. The rates estimated by the study and categorisation of the coastal watersheds could be most helpful in evaluating the cumulative impact of coastal hazards and preparing sustainable development plans. The outcomes may also help to create awareness in more susceptible areas.

Multi-Criterion Analysis of Cyclone Risk along the Coast of Tamil Nadu, India—A Geospatial Approach

A tropical cyclone is a significant natural phenomenon that results in substantial socio-economic and environmental damage. These catastrophes impact millions of people every year, with those who live close to coastal areas being particularly affected. With a few coastal cities with large population densities, Tamil Nadu’s coast is the third-most cyclone-prone state in India. This study involves the generation of a cyclone risk map by utilizing four distinct components: hazards, exposure, vulnerability, and mitigation. The study employed a Geographical Information System (GIS) and an Analytical Hierarchical Process (AHP) technique to compute an integrated risk index considering 16 spatial variables. The study was validated by the devastating cyclone GAJA in 2018. The resulting risk assessment shows the cyclone risk is higher in zones 1 and 2 in the study area and emphasizes the variations in mitigation impact on cyclone risk in zones 4 and 5. The risk maps demonstrate that low-lying areas near the coast, comprising about 3%, are perceived as having the adaptive capacity for disaster mitigation and are at heightened risk from cyclones regarding population and assets. The present study can offer valuable guidance for enhancing natural hazard preparedness and mitigation measures in the coastal region of Tamil Nadu.

Assessment of phytoplankton diversity, distribution, and environmental variables along the southeast coast of India

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 NO3− 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.

Characterization of the Coastal Vulnerability in Different Geological Settings: A Comparative Study on Kerala and Tamil Nadu Coasts Using FuzzyAHP

The acceleration of coastal processes is manifested in the form of coastal erosion, average sea level rise, drastic changes in coastlines, and more turbulent ocean waters. In this study, the coasts of Kerala and Tamil Nadu, India, were selected to identify the effects of increasing coastal processes. Therefore, it is necessary to identify and map vulnerable areas by taking into account the key parameters, such as topographical and socio-economic factors, to relate to coastal processes. The fuzzy Analytical Hierarchy Process (AHP) method was employed to identify the most vulnerable zones. The key findings revealed that about 14% and 2% of the coast of Tamil Nadu and Kerala, respectively, are classified under the physically highly vulnerable category. Similarly, ~17% and ~30% of coastal Tamil Nadu and Kerala, respectively, are highly socially vulnerable. The overall vulnerability assessment showed that 7–8% of both coastal areas were highly vulnerable. We concluded that the Thiruvallur, Chennai, Kanchipuram, Cuddalore, and Nagapattinam coasts on the east coast and the Malappuram, Thrissur, Ernakulam, Alappuzha, and Kollam coasts on the west coast were very highly vulnerable to coastal processes. Identifying vulnerable zones helps to better understand the impacts of rapid coastal processes and, with this prior estimation, the policymakers can take necessary actions to mitigate the irreversible impacts of coastal processes.

Seasonal and spatial variations in the distribution pattern, sources and impacts of microplastics along different coastal zones of Tamil Nadu, India

We investigated spatiotemporal variations of microplastics (MPs) in Coromandel Coast, Palk Bay, Gulf of Mannar, and West Coast of Tamil Nadu, India. MPs abundance varies from 37 ± 1.52 to 189 ± 9.02 items/kg in sediment and 23 ± 15.25 to 155.25 ± 4.16 items/L in water. Highest abundance in monsoon by riverine inflow transports plastic waste to the ocean. MPs sizes 0.5–1 mm are dominant in summer with 16 polymers, while 3–4 mm dominates the monsoon with 23 polymers. Carbonyl Index shows high MP oxidation (>0.31), unrelated to spatiotemporal changes. SEM-EDAX shows weathered MPs carrying hazardous metals. High MP diversity (MPDII = 0.77) of Coromandel Coast points to many sources of pollution and the need for immediate control measures. Pollution load values indicate low degree of MP pollution (<10), polymer hazard index shows level III (10–100) and IV (100–1000), and ecological risk assessment shows minor risks (<150) at present.

Distribution of 226Ra, 232Th and 40K in Kanyakumari beach placer deposits along Tamil Nadu coast, India

Distribution of 226Ra, 232Th and 40K in Kanyakumari beach placer deposits along Tamil Nadu coast, India

Coastal vulnerability assessment for the coast of Tamil Nadu, India-a geospatial approach.

A coastal region is a section of land that borders a significant body of water, often the sea or ocean. Despite their productivity, they are sensitive to even little alterations in the outside environment. This study aims to develop a spatial coastal vulnerability index (CVI) map for the Tamil Nadu coast of India, which has diverse coastal and marine environments that are ecologically fragile zones. Climate change is expected to increase the intensity and frequency of severe coastal hazards, such as rising sea levels, cyclones, storm surges, tsunamis, erosion, and accretion, severely impacting local environmental and socio-economic conditions. This research employed expert knowledge, weights, and scores from the analytical hierarchy process (AHP) to create vulnerability maps. The process includes the integration of various parameters such as geomorphology, Land use and land cover (LULC), significant wave height (SWH), rate of sea level rise (SLR), shoreline change (SLC), bathymetry, elevation, and coastal inundation. Based on the results, the very low, low, and moderate vulnerability regions comprise 17.26%, 30.77%, and 23.46%, respectively, whereas the high and very high vulnerability regions comprise 18.20% and 10.28%, respectively. The several locations tend to be high and very highdue to land-use patterns and coastal structures, but very few are contributed by geomorphological features. The results are validated by conducting a field survey in a few locations along the coast. Thus, this study establishes a framework for decision-makers to implement climate change adaptation and mitigation actions in coastal zones.

Impact of tropical cyclone Ockhi on the marine fishery resource assemblages along the Kerala and Tamil Nadu coast, India

Impact of tropical cyclone Ockhi on the marine fishery resource assemblages along the Kerala and Tamil Nadu coast, India

Biological Control of sheath blight disease in rice using Marine Actinomycetes (Streptomycetes rochei) AMET A311 strain

The soil samples were taken from the rhizome soil of coastal sand dune plants along the Hare islands, Tuticorin, East Coast of Tamil Nadu, in order to isolate an efficient antifungal marine actinomycetes. A total of 70 actinomycetes were isolated from the samples collected. Based on colony morphology, aerial mass color, melanoid pigments, reverse side pigments, soluble pigments, spore chain morphology and spore surface, 62 of the 70 isolates were identified as distinct. Fifty isolates from the 62 distinct colony were chosen for the antifungal activity based on their capacity to endure salt concentrations over 1M. Rhizoctonia solani, a fungus pathogen, was tested against each of the 50 identified strains. Rhizoctonia solani, a fungus, was resistant to about 36% of the isolates. AMET 307, AMET 308 and AMET 307, AMET 311 and AMET 315 exhibited the highest level of antifungal activity against Rhizoctonia solani. Using 16s rRNA sequencing, this effective antifungal strain was further identified as the Streptomycetes rochei AMET 311 strain (KT334600).

Soil Structure interaction of Laterally Loaded Piles

The rapid development of the global economy has led to an increased energy demand throughout the world. More than 70% of the world’s energy consumption is from the use of fossil fuels. In the wake of rising global temperatures and increased carbon emissions, policymakers across the globe think about alternate and renewable ways of energy generation, among which wind energy is a promising energy source. Offshore wind turbines are new technologies and are challenging when it comes to their installation in harsh ocean environment as they are subjected to environmental loads caused by wind, wave and currents. These loads are then transferred to foundation. Monopiles are the most common foundations used in offshore wind turbines today and therefore its analysis is important. Monopiles are single large diameter tubular steel piles of diameter 3–7 m driven into the seabed with typical penetration depth of 25–30 m, and are subjected to lateral dynamic loads. Soil structure interaction of monopile is an important aspect to be considered in its design and for the present study, PLAXIS 3D geotechnical software is used for the soil-pile interaction and the corresponding displacement behaviour of the pile under study. The dynamic analysis due to the wave forces on the monopile is carried out using wave data off Gulf of Mannar, near the Tamil Nadu coast, and the embedment length of the pile is varied to study the effect of diameter of pile and embedment length on the displacement characteristics of the pile.

Assessment of monitoring of tide and wave-induced flow in the saturated beach water table in southern coastal Tamil Nadu, Thoothukudi and Kulasekharapatnam

Assessment of monitoring of tide and wave-induced flow in the saturated beach water table in southern coastal Tamil Nadu, Thoothukudi and Kulasekharapatnam

Statistical analysis of shoreline change reveals erosion and baseline are increasing off the northern Tamil Nadu Coasts of India

Many tourists have been recently attracted towards the coasts around the world, especially to the large urban centres and economically significant areas. In the last four decades, there is a significant increase in the key coastal developments and tourist's attractions like major ports, minor ports, fishing harbours, desalination plants, shore protection structures, and many more along the southeast coasts of India, in particular, northern Tami Nadu coastal stretches. The shoreline change study of these regions were carried out using the geospatial technologies (satellite remote sensing and geographical information system) to examine potential modifications occurred during the last 32years between March 1990 and May 2022. This study used Landsat satellite images of spatial resolution 30m to track the shoreline changes which was extracted using the Digital Image Processing software and techniques. In addition, the United States Geological Survey (USGS) developed Digital Shoreline Analysis System (DSAS) v5.2 software, an add-on tool to ArcGIS used for the statistical analysis to compute the shoreline rate of change. The linear regression rate (LRR) and end point rate (EPR) statistics were used to identify the eroding, accreting, and stable shoreline between Kattupalli coast and Kalpakkam coast of the northern Tamil Nadu coasts. This shoreline study of 106km was carried out by dividing it into six zones (zone 1 to zone 6), and the DSAS analysis conveys that the shoreline of zone 1 (Kattupalli) and zone 2 (Ennore) shows erosion compared to other four zones. In locations where the coast is vulnerable, national mitigation measures must be implemented.

Carbonate landforms of Rameswaram Island, Tamil Nadu coast, India: a review

Carbonate landforms of Rameswaram Island, Tamil Nadu coast, India: a review

Coastline change rate estimation on the southern coastal districts of Tamil Nadu, India using the multi temporal Google Earth images and GIS based statistical approach

&lt;p&gt;Coastal erosion is the process of wearing away material from the coastal profile due to an imbalance in the supply and export of material from a particular section of the coast which cause property damage, and the loss of land. This study investigates the rate of erosion and accretion along the southern coast of Tamil Nadu which was exposed to a lot of tourism and development activities. The shorelines were delineated for the years 2000,2005,2010,2015 and 2020 on the high-resolution multi-temporal satellite images in the Google Earth Pro software by visual interpretation. The long-term and short-term changes were studied by three statistical parameters functionalized in DSAS v 5.0 tool in ArcGIS 10.6 software such as endpoint rate, net shoreline movement and linear regression rate (Cenci et al., 2018). The positions of the shoreline in 2030 and 2040 are forecasted using the Kalman filter-based forecast tool in DSAS and the changes were analysed. During the study period, the average rate of changes in Kanyakumari is -1.26 m/year, Tirunelveli is -1.01 m/year and Tuticorin is -1.09 m/year. the transects showed significant erosion along 19.54% of Kanyakumari, 3.79% of Tirunelveli, and 17.81% of Tuticorin coasts, and significant accretion is observed in 1.31% of Kanyakumari, 1.07% of Tirunelveli and 3.02% of Tuticorin coasts. The outcome of shows that erosion is prevailing on the Kanyakumari coast and erosion is prevailing in Tuticorin.&lt;/p&gt;&#x0D;

Estimating built-up risk from multi-natural hazards: A case study of Northern coastal plains of Tamil Nadu

The Tamil Nadu state of India possesses a vast coastline of 1076 ​km and is highly vulnerable to many climate change-induced natural hazards. It is essential to evaluate the elements at risk to the coastal hazards and map their spatial variations for the densely populated Tamil Nadu coast. Most of the disaster risk studies had concentrated much on delineating hazard-prone regions based on the overall analysis of multiple parameters. For the first time, this study estimated the risk for built-up areas at the micro-administrative level for the northern coastal plains of Tamil Nadu. The built-up areas in the coastal stretch (within 40 ​m from MSL) were delineated and categorised based on their density and structure. Also, we conducted a focus group survey from the deprived communities in the study area. Our result shows that out of 1848 sq. km. built-up area in the study region, 127 sq. km. fall under the very high category of the impacts of six significant natural hazards: cyclones, storm surges, Tsunami, floods, earthquakes, and shoreline erosion. Our results show that the built-up areas in Chennai, Pondicherry, Karaikal, and towns/villages of Cuddalore and Nagapattinam are at very high to high multi-hazard risks. Since the present study focuses on the built-up damage at the micro-level, the results can be upscaled and used for local and state-level planning strategies.

Paradujardinia halicoris infection in dugong (Dugong dugon) carcasses beached along the coast of Tamil Nadu, India

Paradujardinia halicoris infection in dugong (Dugong dugon) carcasses beached along the coast of Tamil Nadu, India

Heavy metal concentration in marine edible fishes and associated health risks: An assessment from Tamil Nadu coast, Bay of Bengal

To assess food safety, the edible portion (muscle tissue) of the 91 different species of marine fish was studied and analyzed for metal contents. The fish samples were collected during 2017–2018 from the southwestern Bay of Bengal region at Kalpakkam coast. The hierarchy of the metals in muscle tissue was in the order of Fe > Zn > Al > Cr > Ni > Mn > Cu > Pb > Co > Cd, as reported in studied fishes. Among fish species, Lates calcarifer (469.69 mg/kg dry weight (dw) and Siganus lineatus (64.74 mg/kg dw) had the highest and lowest total metal content in their muscle tissue. Fe & Zn together contributed ̴ 70% of the total metal content of 72 fish species. The observed elevated concentrations of Al (1.96–46.6, average: 20.39 mg/kg dw) and Cr (1.93–55.24, average: 15.2 mg/kg dw) in fish compared to other regions could be attributed to localized contamination. The PCA results suggested a higher accumulation of Al, Cd, Cu, & Zn, in pelagic-neritic fishes and Co, Cr, Fe, Mn, Ni, & Pb in demersal fishes in comparison to fishes occupying other habitats. The levels of metals in fish muscle are in compliance with the maximum regulatory limit specified for fish by the Food Safety and Standards of India (FSSAI), European Commission (EC), Joint Food and Agricultural Organization of the United States/World Health Organization (FAO/WHO), suggesting that the fishes are safe for human consumption. The non-carcinogenic (estimated daily intake; target hazard quotient, hazard index) and carcinogenic risk (target cancer risk) assessment performed indicated no apparent risk to the adult consumer.

Microplastic Contamination Analysis For Chennai Coastal Region

Microplastic contamination in the Chennai coastal region is a growing concern due to the intake of abandoned garbage from various sources. This study aimed to assess the extent of microplastic contamination by analyzing microplastic trash collected from 25 spots along the Tamil Nadu coast, spanning a distance of 1076 kilometers. The results revealed that microplastic contamination was more prevalent during higher wave conditions compared to lower tides. Shorelines near riverbanks exhibited significantly higher quantities of microplastics than those affected by fisheries and tourist activities. The main types of microplastics found were polyethylene, polypropylene, and polystyrene, with plastic shards comprising the majority of the trash (47-50%). Furthermore, analyses of fish species collected from shore regions showed that 10.1% of the fishes had consumed plastic particles. This emphasizes the potential risk of microplastics entering the marine food chain. The study highlights the need for microplastic filtering from estuaries, coastline waters, and other potential sources. In conclusion, microplastic contamination poses a serious hazard to the Chennai coastal region. Urgent measures are required to mitigate and reduce microplastic pollution, particularly near river openings, to protect the marine ecosystem and the food chain. Efforts should focus on preventing the entry of microplastics into the environment and promoting sustainable waste management practices to safeguard the coastal ecosystem.

Assessing the geographical distribution of carnivorous and planktivorous fishes in the western Bay of Bengal

There is a clear distinction in the feeding habits of fishes between the northeastern and southeastern Arabian Sea (west coast of India) — the north is carnivorous, and the south is planktivorous —, but such a distinction is not available for the western Bay of Bengal (BoB; comprising the east coast of India and the coasts of Sri Lanka and Bangladesh). We address this question by using publicly available landing data of finfishes for the four Indian states (Tamil Nadu, Andhra Pradesh, Odisha, and West Bengal) located along the western boundary of the BoB. Our analysis shows that the southwestern BoB is rich in fisheries and is more planktivorous compared to the northwestern BoB, which is more carnivorous. North–south variability exists even within the group of fishes such as anchovies and carangids. The meagre landing information for Sri Lanka and Bangladesh suggests that they show planktivorous and carnivorous characteristics of the southwestern and northwestern BoB, respectively. We show that monthly data and clarity on where the fish were caught are necessary to link the climatic conditions to the fishery along the western BoB. The landings on the Arabian-Sea and Gulf-of-Mannar part of the Tamil Nadu coast must be separated from the landings on its BoB coast. This separation can not be done with existing landing data and should be the first step in analysing fisheries data from the western BoB. The challenges in delineating the distribution of finfishes using available data illustrated here deliver guidance for future data collection and analysis at higher spatial and temporal scales for sustainable fisheries resource management in the region.