Ramesh CH

National Institute of Oceanography | nio · Biological Oceanography Division ( BOD )

The health of coral reefs in Palk Bay has been influenced by several natural and anthropogenic stressors over the last four decades. This study assessed the resilience potential of Scleractinian corals and their associated biota in Palk Bay to understand the corals' capacity for resistance and provide a detailed account of positive and negative fac...

Pigments and other secondary metabolites originating from marine microbes have been a promising natural colorants and drugs for multifaceted applications. However, marine actinobacteria producing such natural molecules are least investigated in terms of their taxonomy, chemical diversity and applications in biomedical, textile, and food industries....

Mangrove productivity in the coastal regions mainly depends on the tidal influx, which supplies essential nutrients. Less tidal exposure and reduced water uptake levels can severely affect mangrove growth. In this context, we identified two distinct mangrove zones of Avicennia marina (Forssk.) Vierh., at a remote geographical zone, southeast coast...

Pink pigmentation on massive corals is quite commonly observed in the global reefs, but its function on the surface area of corals is less understood. In the present study, the coral video transect method was employed to document the incidence of pink pigmentation on Porites colonies from 21 islands under the Gulf of Mannar Marine Biosphere Reserve...

In India, intertidal seaweed resources are widely investigated and utilized for various applications, whereas reef associated seaweed resources and their impacts on corals are lesser known. Thus, the present study investigated the diversity and impacts of macroalgae and cyanobacteria on coral reefs distributed in 21 islands under the Gulf of Mannar...

Investigations on indigenous and non-indigenous invasive flora and fauna of the certain geographical area are always important to assess their impact on native biodiversity and control their spread by making conservation strategies to protect biodiversity. In this study, we have encountered overwhelming growth of four invasive seaweed species, Caul...

nvestigations on indigenous and non-indigenous invasive flora and fauna of a certain geographical area are always important to assess their impact on native biodiversity and control their spread by making conservation strategies to protect biodiversity. In this study, we have encountered overwhelming growth of six seaweed species, Caulerpa racemosa...

The exploration of the microbial world in research continues to be fascinating and unending in several aspects of taxonomy, genomics, evolution, and industrial applications. Among numerous known microbes from different environments, aquatic microbes have attained significant demand for decades to address the benefits of aquatic microbes for societa...

Antarctica is a remote and pristine region. Yet it plays a vital role in biogeochemical cycles of global anthropogenic contaminants, such as persistent organic pollution (POPs). This work reports the distribution of legacy and new POPs in surface and depth profiles/deeper water of the Southern Indian Ocean (SIO) and the coast of Antarctica (COA). S...

In 2021, a reef restoration programme was introduced to the selected sites of Palk Bay to improve coral nurseries and assist with the establishment of artificial reefs by implementing local coral transplantation. To monitor the growth and survival of transplanted corals, numerous fish assemblages have been observed in restoration sites which are po...

Sadhukhan K, Chatragadda E, Shunmugaraj T, Murthy MVR. 2022. Health monitoring status of corals in Gulf of Mannar and Palk Bay (India) with special reference to coral bleaching event. Indo Pac J Ocean Life 6: 61-73. Coral reef ecosystems are highly important regarding ecological, cultural, and economic values. Unfortunately, these ecosystems are de...

Pigments from bacteria, fungi, yeast, cyanobacteria, and microalgae have been gaining more demand in the food, leather, and textile industries due to their natural origin and effective bioactive functions. Mass production of microbial pigments using inexpensive and ecofriendly agro-industrial residues is gaining more demand in the current research...

The global emergence of antimicrobial resistance (AMR) needs no emphasis. In this study, the in vitro stability, safety, and antimicrobial efficacy of nanosilver-entrapped cinnamaldehyde (AgC) against multi-drug-resistant (MDR) strains of enteroaggregative Escherichia coli (EAEC) were investigated. Further, the in vivo antibacterial efficacy of AgC...

Since the discovery of the Green fluorescent protein from crystal jellyfish Aequorea victoria, many fluorescent organisms have been identified from different parts of the world. As a result, various fluorescent proteins such as GFP, RFP, and DsRed are discovered and widely used in genetic engineering studies to label a wide range of proteins and ge...

Coral reefs of Gulf of Mannar (GoM) often undergo acute disturbances which caused mass mortality of corals in GoM over the past few decades. Mass mortality of corals have altered the live coral cover in GoM and become the permanent resident of many local threats. During extensive underwater survey from November, 2019 to February, 2019, surprisingly...

The occurrence of polypropylene and polyethylene bags in the coral reefs of the Mandapam group of Islands has become a concern. These plastic bags pose a potential threat to corals, reef-associated animals, and divers. Field surveys were conducted to track the source of origin of these plastics along the islands and mainland beaches. This study ind...

Light emission from marine organisms had been a mesmerizing research topic since ancient times (Moline et al., 2013). Luminous organisms belonging to different taxonomic group use various luciferin molecules to produce light upon oxidation reaction in presence of luciferase enzyme (Haddock et al., 2010). Most bioluminescent organism use light for d...

Seaweeds are a commanding component of the marine plant life complex in the structure of coastal environmental biodiversity, and they are functioning as renewable living wherewithal to the global coastal communities. They are the source materials approximately for 27 health benefits and varied makeup applications. The important applications of seaw...

Aims: Present study aims to highlight an accidental death of a male Dwarf Sperm Whale scientifically known as Kogia sima which found to be as Least Concern (LC) as per IUCN Red List data. Kogia sima represents important higher trophics of marine ecosystem which faced the several threats and conservation need in Gulf of Mannar, India. Study Design:...

Bioluminescence is a natural light emitting phenomenon that occurs due to a chemical reaction between luciferin and luciferase. It is primarily an innate and inherited trait in most terrestrial luminous organisms. However, most luminous organisms produce light in the ocean by acquiring luminous symbionts, luciferin (substrate), and/or luciferase (e...

Bioluminescence is a natural light emitting phenomenon that occurs due to a chemical reaction between luciferin and luciferase. It is primarily an innate and inherited trait in most terrestrial luminous organisms. However, most luminous organisms produce light in the ocean by acquiring luminous symbionts, luciferin (substrate), and/or luciferase (e...

Marine Streptomyces species are underexplored for their pigment molecules and genes. In this study, we report the genome of the undecylprodigiosin biosynthesizing gene cluster carrying Streptomyces sp. strain BSE6.1, displaying antioxidant, antimicrobial, and staining properties. This Gram-positive obligate aerobic bacterium was isolated from the c...

Seaweed exploitation in mainland India was started in early 1970s for various applications. The checklist of seaweeds of mainland India was well documented during 2001. However, rich marine macroalgal diversity found in island ecosystems of Andaman and Nicobar Islands have not been explored until today due to inaccessibility to most remote and prot...

Coral bleaching now becomes an annual phenomenon in Gulf of Mannar (GoM) and Palk Bay (PB). In 2019 and 2020, reefs are completely bleached by the effect of high sea surface temperature which not only impinge on the reef building corals but also triggers the growth of unwanted macroalgae in live reefs. The consequences of this major threats are lon...

Coral bleaching now becomes an annual phenomenon in Gulf of Mannar (GoM) and Palk Bay (PB). In 2019 and 2020, reefs are completely bleached by the effect of high sea surface temperature which not only impinge on the reef building corals but also triggers the growth of unwanted macroalgae in live reefs. The consequences of this major threats are lon...

Toxic heavy metals pollution posed severe health hazards to the environment and biodiversity. Therefore, the development of rapid and non-invasive bioassays is in the race to monitor toxic chemicals using novel approaches. This study isolated and characterized an intense blue luminescence-producing marine bacteria, Vibrio campbellii STF1, for biose...

The term bioluminescence refers to a conspicuous light emission displayed by numerous aquatic and terrestrial organisms. This phenomenon has so far not been observed in several taxonomic groups like archaea, protista, platyhelminthes, chelicerata, cephalochordata, amphibians, reptiles, birds, plants, and mammals. However, some luminescent bacteria,...

Marine tunicates are identified as a potential source of marine natural products (MNPs), demonstrating a wide range of biological properties, like antimicrobial and anticancer activities. The symbiotic relationship between tunicates and specific microbial groups has revealed the acquisition of microbial compounds by tunicates for defensive purpose....

In April 2019, massive blooms of Trichodesmium erythraeum (8×10 5 filaments/ml) forming several long chains extended up to few kilometres were observed nearby the Mandapam group of islands, Southeast coast of India, Tamil Nadu. Bloom of Synechococcus sp. (3×10 5 cells/ml) was also recorded near the Kundukal jetty, Mandapam region merely. There were...

Mass mortality of sea urchin, Salmacis virgulata scattered over the periphery of Dhanushkodi beach, was observed on February 13, 2019. More than 100 numbers of recently dead and dying specimens were found within a 10 m 2 area on the sandy beach. Beach profiles indicated several hundreds of exoskeletons of previously dead S. virgulata were washed as...

Coral reefs provide a suitable habitat for many marine flora and fauna. Zoanthid is one of the most common inhabitants in coral reef habitats. A sub-massive colony of Sphenopid Zoanthid species Palythoa tuberculosa belonging to the order Zoantharia was documented for the first time from Gulf of Mannar (GoM) during an intensive coral reef monitoring...

Coral reefs provide a suitable habitat for many marine flora and fauna. Zoanthid is one of the most common inhabitants in coral reef habitats. A sub-massive colony of Sphenopid Zoanthid species Palythoa tuberculosa belonging to the order Zoantharia was documented for the first time from Gulf of Mannar (GoM) during an intensive coral reef monitoring...

Rhodoliths are the prominent global reef builders, providing a hard calcium carbonate substrate to develop coral polyps and several marine algae. Studies on rhodoliths in the Gulf of Mannar Biosphere Reserve are very scarce. The present study investigated the various forms of crustose coralline algae inhabiting coral reefs in three islands of the G...

Microbial pigments play multiple roles in the ecosystem construction, survival, and fitness of all kinds of organisms. Considerably, microbial (bacteria, fungi, yeast, and microalgae) pigments offer a wide array of food, drug, colorants, dyes, and imaging applications. In contrast to the natural pigments from microbes, synthetic colorants are widel...

A massive Scyphozoan jellyfish bloom has been encountered in branching coral, Acropora dominated reef area in the southern part of Hare Island of Gulf of Mannar region, Tamil Nadu. The live specimens were identified as Pelagia noctiluca (Forskål, 1775), adding a new occurrence record to the Gulf of Mannar biodiversity. A sudden outburst of P. nocti...

Several kilometers of green tides (GT) formed by seaweed and seagrass were recently observed in intertidal, swash, and shallow subtidal zones of Palk Bay and Gulf of Mannar regions, southeast coast of Tamil Nadu, India. On a finer scale (few hundreds of Kgs), GT of Ulva rigida observed in the Palk Bay region during November 2018 was due to eutrophi...

The phytoplankton diversity, distribution, density and their relationships to physicochemical variables were investigated using multivariate analyses. Day and night samples were collected monthly between November 2011 and April 2012 from two different stations, Chatham and Junglighat in South Andaman Island. A total of 204 species and 65 genera wer...

Several kilometers of green tides (GT) formed by seaweed and seagrass were recently observed in intertidal, swash, and shallow subtidal zones of Palk Bay and Gulf of Mannar regions, southeast coast of Tamil Nadu, India. On a finer scale (few hundreds of Kgs), GT of Ulva rigida observed in the Palk Bay region during November 2018 was due to eutrophi...

The phytoplankton diversity, distribution, density and their relationships to physicochemical variables were investigated using multivariate analyses. Day and night samples were collected monthly between November 2011 and April 2012 from two different stations, Chatham and Junglighat in South Andaman Island. A total of 204 species and 65 genera wer...

The inception of bioluminescence by Harvey (1952) has led to a Nobel Prize to Osamu Shimomura (Chemistry, 2008) in biological research. Consequently, in recent years, bioluminescence-based assays to monitor toxic pollutants as a real-time marker, to study various diseases and their propagation in plants and animals, are developed in many countries....

The discovery of green fluorescent protein (GFP) from jellyfish Aequorea victoria has provoked numerous studies to unveil the myriads of biomedical applications. Consequently, several studies also revealed the prevalence of fluorescence in different marine and terrestrial organisms. However, since GFP's discovery or the Nobel prize award on GFP, th...

Seagrasses are unique marine flowering plants that play an important ecological role by yielding primary production and carbon sequestration to the marine environment. Seagrass ecosystems are rich in organic matter, supporting the growth of bio-medically important epi and endophytic microorganisms and harbor rich marine biodiversity. They are an es...

Heat sensitive pigment production by various coral forms has been observed in the reef flats of Gulf of Mannar Marine Biosphere Reserve, southeast coast of Tamil Nadu, India. Around 13% corals have produced purple-blue pigmentation to yellowish cream colors. These colors indicate the immunity response of corals to tolerate heat stress during bleach...

The diversity, distribution, and mechanisms of bacterial speciation of Vibrio species belonging to Harveyi clade are an important global research interests due to their pathogenic activity in coastal environments. Luminous bacteria are also known to act as environmental indicators in coastal waters. This study demonstrates that luminous bacteria be...

Coral bleaching in Gulf of Mannar and Palk Bay was encountered while intensive reef health monitoring surveys conducted during the month of April to May, 2019. Surveys were carried out at 12 different locations of Gulf of Mannar and 2 locations of Palk Bay region. Reef building coral genera Porites sp., Acropora sp., Montipora sp., Favites sp., and...

The global climate change is known to involve in the decline of biodiversity from different ecosystems, including coral reefs worldwide. The spatial distribution of reef associated flora and fauna in the Gulf of Mannar (GoM) Marine Biosphere Reserve (GOMMBR) are declined due to damage of coral reefs by three major global problems observed in coral...

On 11 th September, 2019, coastal waters near to offshore islands of Mandapam region appeared in dark green colour, which is caused by bioluminescent dinoflagellate Noctiluca scintillans, commonly called as Sea Sparkle. Extensive monitoring was carried out during 11 th to 25 th September, 2019 to assess the impact of this bloom on offshore islands...

The application of marine plants such as seagrasses, seaweeds and mangroves for the production of perfumes are relatively less familiar to perfume industry. In the present study, a red seaweed Portieria hornemannii showing strong fragrance, collected from coral reefs of Gulf of Mannar, southeast coast of Tamil Nadu, India is proposed as a potential...

The diversity, distribution, and mechanisms of bacterial speciation of Vibrio species belonging to Harveyi clade are an important global research interests due to their pathogenic activity in coastal environments. Luminous bacteria are also known to act as environmental indicators in coastal waters. This study demonstrates that luminous bacteria be...

Coral reefs in the Gulf of Mannar (GoM) and Palk Bay regions are facing potential threats from climate change, sedimentation and anthropogenic activities. Considerably, coral reefs in these two regions are highly damaged due to frequent bleaching events caused by increased sea surface temperature (SST) recorded over the past two decades. Recently,...

The present study investigated luminous bacterial species composition from non-bioluminescent big fin reef squid, Sepioteuthis lessoniana for the first time and revealed a new insight on the occurrence of five distinct luminous bacterial species such as Vibrio harveyi, V. campbellii, V. vulnificus, V. alginolyticus and Photobacterium damselae indic...

Since past three decades, coral reefs of the world are degrading at large scales due to climate change and through combination of anthropogenic and natural disturbances. Coral reefs in the 21 islands of Gulf of Mannar Marine Biosphere Reserve, Southeast coast of Tamil Nadu, India are also greatly damaged by frequent bleaching events, destructive fi...

This study is aimed to determine the distribution, diversity and bioprospecting aspects of marine pigmented bacteria (MPB) isolated from pristine Andaman Islands, India. A total of 180 samples including seawater, sediment, marine plants, invertebrates, and vertebrates were collected and investigated for isolating pigmented bacteria. Results reveale...

Occurrence of massive blooms of dinoflagellates and other phytoplankton species in the coastal waters indicate the health condition of coastal waters. Dinoflagellate blooms reported around the world are known to be harmful to the coastal marine flora and faunal communities. Therefore monitoring such blooms occurring in the coastal waters are import...

Bacterial bioluminescence is emitted due to regulation by lux genes present on the chromosomal DNA. Earlier studies have attempted to find possible occurrence of lux genes on plasmid DNA (pDNA) but did not find such incident. Evidently, the present study reveals the rare incidence of luxA gene on pDNA analysed using poly-merase chain reaction. We d...

Indigenous and non-indigenous invasive algal species introduction or prevalence is one of the major conce rns to protect the native coastal environment. Globally, several studies have reported the effect of invasive alga Caulerpa on coral reefs. To establish the genetic variation between indigenous and non-indigenous invasive species, attempts have...

Geologic processes are the major drivers for constructive and destructive topography of Island and mainland. Therefore, understanding these processes is of great importance to protect the coastal lands from erosion. Although coral reefs of Gulf of Mannar (GoM) and Palk Bay regions are well studied, several other geological aspects are apparently sc...

During an intensive coral reef monitoring survey at Hare Island and Manoli Island under Mandapam group of Islands, and Valimunai Island of Keezhakarai group, in the month of February 2019, the common brittle star Ophiactis savignyi was found inside the tissue of chocolate sponge Spheciospongia sp. Adult, young and juveniles of O. savignyi were enco...

Luminous fireflies are a roadside attraction group of insects which act as environmental indicators and indicate the quality of surrounding milieus. However, recent studies suggest that water pollution and climate change are involved in the decline of firefly populations around the world, and have sounded an alarm regarding the conservation of the...

In the present study bleaching of different sea anemone species such as Stichodactyla mertensii, Stichodactyla gigantean, Stichodactyla spp., Stichodactyla haddoni, and Cryptodendrum spp. were observed from Appa Island in Gulf of Mannar region. This bleaching was due to elevated sea surface water temperature.

Reef associated ascidians are least studied from coral reef environments of Gulf of Mannar region. The present study observed the infestations of two ascidians on coral reef biota of Hare Island in Gulf of Mannar region, southeast coast of Tamil Nadu, India. These two ascidian species are observed to cause smothering on reef biota. Therefore, it is...

Coral Reefs in Gulf of Mannar is degrading with fatser rate due to several environmental stress over the past few decades. Under this severe degredation phase, our work has observed significant coral recruitment at Hare Island and Manoli & Manoliputti Island of Gulf of Mannar. Occurrenc of new recruitment of corals increseas the live coral cover pe...

Coral Reefs in Gulf of Mannar is degrading with fatser rate due to several environmental stress over the past few decades. Under this severe degredation phase, our work has observed significant coral recruitment at Hare Island and Manoli & Manoliputti Island of Gulf of Mannar. Occurrenc of new recruitment of corals increseas the live coral cover pe...

Coral reefs are extensively studied around the world with regard to their taxonomy, distribution, diversity, bleaching events, diseases, conservation, and restoration aspects. However, exhibition of blue pigmentation by corals under certain stressed condition such as high temperature and bleaching events has not been widely investigated. In the...

Current days enzymes obtained from the marine microorganisms are gaining global market value because of their unique nature and catalytic properties. Marine is a complex environment and has vastly diversified ecosystem. Organisms which live in this environment secrete multifarious enzyme systems to become accustomed to surrounding habitats. Marine...

The present perspective discusses the current need for following the standard journal citation to researchers, scientists and new comers into research field. Based on the current situation, we understand that standard citation style would certainly help everyone to progress their research. This universal style will play an important role in saving...

Coral reefs in the Gulf of Mannar Marine Biosphere Reserve (GOMMBR) have been facing potential threats from bleaching, sedimentation and significantly algal assemblages. In the present study, bloom of cyanobacterium Lyngbya majuscula overgrowing reef building corals Acropora sp., Porites sp., Echinopora sp. and Goniastrea sp. was observed in Poovar...

A rare habitat of massive coral Porites lutea growing on concrete manhole rings was observed at Vedalai coastal waters in the present study. This coral species is attacked by boring sponge Cliona sp. which is usually prevalent in coral reef areas. Interestingly, this boring sponge, Cliona sp. attacking P. lutea was also observed to be attacked by a...

Antimicrobial properties of several nonpigmented bacteria isolated from the marine environment have been well understood. However, marine bacteria with distinct asset of pigmentation have not been studied intensively and explored unlike nonpigmented bacteria. Recently, several studies have found multidrug-resistant microbes against various diseases...