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The Andaman and Nicobar Islands host diverse ecosystems with abundant marine life distributed across their coral reefs, seagrass meadows, mangrove forests, and estuaries. While many individual islands are protected as sanctuaries, biosphere reserves, national parks, or tribal reserves, there are also two marine parks: Rani Jhansi Marine National Park, adjacent to Havelock (Swarajdweep) Island and Mahatma Gandhi Marine National Park (MGMNP) off the southern coast of South Andaman Island.
Being largely isolated, this archipelago has spurred endemism (i.e., species found only in a single defined geographic location) in both terrestrial and marine flora and fauna. In 2013, the Zoological Survey of India (ZSI) recorded 872 endemic species of fauna in terrestrial and 245 in the marine ecosystems of the island group.
Established in 1983, MGMNP became the second marine national park in India, created under the Wildlife Protection Act of 1972. The park lies 20 km from the capital, Port Blair (now Sri Vijaya Puram), in Wandoor, South Andaman. It comprises 15 islands, spanning nearly 281 square kilometres, with 220 square kilometres of territorial waters. In addition to its diverse marine ecosystems, the national park also features pristine tropical evergreen forests, which support a variety of terrestrial flora and fauna. Within the national park, Jolly Buoy and Red Skin Island are open to day visitors. However, each island is only open for six months of the year (November to April), to avoid overtourism and preserve the ecosystem. Visitors can rent glass-bottom boats and spend the day on the sandy shores of Jolly Buoy or take a stroll through the mangrove walkway of Red Skin. In recent years, water-based adventure activities have been curtailed due to frequent sightings of saltwater crocodiles (Crocodylus porosus), which inhabit MGMNP’s estuarine habitats.
Coral Gardens
(1) The Andaman and Nicobar Islands host 89 per cent of India’s coral diversity. MGMNP was established primarily to protect marine biodiversity and ecosystems such as coral reefs, which are ubiquitous within the park. A variety of hard coral species are found in its shallow waters, where permeating light supports the growth and survival of zooxanthellae algae that the corals host and depend on. (2) A group of sea goldies or orange basslet fishes (Pseudanthias squamipinnis) over Acropora coral (on the left); these territorial fish tend to stay within a few metres of their chosen coral. They live as a harem of many females with one or two males. Interestingly, when a male is removed, the dominant female undergoes sex change over 2-4 weeks and becomes the harem’s new male.
(1) Gorgonians or sea fan corals, a type of soft coral, are particularly visible around Tarmugli, Grub, and Red Skin islands in MGMNP. These “soft corals” are unlike hard corals, which have skeletons made of calcium, and instead have a flexible skeleton made of proteins. They are often found swaying, oriented perpendicular to the currents to ensure efficient capture of plankton through filter-feeding. (2) The orange and red coloured cup corals are Tubastraea, a genus of heterotrophic coral that does not contain any zooxanthellae algae. They can be observed growing underneath ledges and in deeper waters where there is less competition due to little or no sunlight. They are nocturnal and use their tentacles to capture zooplankton.
Fish Life
(1) Trevallies such as the bigeye trevally (Caranx sexfasciatus) or bluefin trevally (Caranx melampygus) are common around MGMNP. (2) Schools of blackfin barracudas (Sphyraena qenie) lurk in the water column, sometimes in large schools. (3) Painted sweetlips (Diagramma pictum) and large spot sweetlips (Plectorhinchus macrospilus) are often found resting below ledges or reefs along with groupers, such as this whitespotted grouper (Epinephelus coeruleopunctatus) on the right, that could easily be missed at first glance.
Diving in MGMNP, you may catch Marlin and Coral of the Disney movie Finding Nemo; they are the famous orange-coloured (1) ocellaris clownfish (Amphiprion ocellaris) often nestled in their protective anemones. You will also likely encounter schools of fusilier fish (sometimes visible even from the boat) such as the goldband or yellowband fusilier (Pterocaesio chrysozona) with a prominent yellow stripe along its side, and yellowback fusiliers (Caesio xanthonota) which have yellow backs and predominantly blue bodies.
Marine Critters
Within hard corals like Porites and branching Acropora, you can spot many small critters like Christmas tree worms (Spirobranchus giganteus) and rust-spotted guard crabs (Trapezia rufopunctata). (1) Christmas tree worms are tube-building polychaete worms that permanently live within a tube bored into live corals. Feather-like tentacles cover their appendages, which protrude from their bodies and resemble tiny Christmas trees. The worm uses these tentacles to draw oxygen from the water and trap prey. (2) The rust-spotted guard crab has a unique pattern that likely helps it camouflage within colourful corals.
Coral Reef Monitoring and Restoration
Dr Titus Immanuel, a postdoctoral research fellow at the Indian Institute of Science, has been diving in MGMNP since 2009. During 2023-2024, he conducted fieldwork to assess the vulnerability and resilience of coral reef ecosystems to human disturbance and climate change. He observes, “It was interesting to see many large Porites that had died during previous bleaching events (likely linked to El Niño years) had survived in some areas. Over the years, the surviving parts have grown and formed new massive Porites colonies at the edges of the bleached reef. This pattern is commonly observed in shallow-water Porites, where the upper portions die due to repeated bleaching, leaving only the edges alive. These ring-shaped formations are called microatolls. The pink portions are crustose coralline algae that assist in the settlement of coral larvae, probably aiding in the settlement and survival of the many small branching corals seen here.”
Coral bleaching has been observed in the South Andaman Islands in 2005, 2010, 2016 and more recently in 2024. The bleaching events in 2010 and 2016 and the recovery of the corals were extensively documented. They indicated that the corals are a lot more resilient and are exposed to fewer anthropogenic (human-induced) threats in the national park. Although corals can withstand temporary increases in temperatures by 1-2 degrees Celsius above their tolerance range, prolonged exposure leads to mass bleaching. In 2015, Long-term Ecological Observatories (LTEO), a multi-disciplinary and multi-institutional programme was established to assess the health of reef systems, and the long-term monitoring of coral reefs in the Andaman and Nicobar Islands was initiated in 2021, The Andaman and Nicobar Forest Department has also deployed many artificial reefs and engineered structures around Grub and Tarmugli Islands. Fragments of broken corals are tethered to these structures, providing them with a new substrate on which to grow and ultimately mimic natural reefs and their functions.
Research and Conservation
Another key objective of establishing MGMNP was to protect the breeding grounds for sea turtles. Four species of sea turtles — hawksbill, green, olive ridley, and leatherback — nest within MGMNP. The first evidence of a leatherback nest in the Andaman and Nicobar Islands was recorded from Jahaji beach of Rutland Island. In his survey in 1977, the famed naturalist Satish Bhaskar reported “5 leatherback eggshells” and mentions “presumptions lead one to the exciting possibility that the beach was a reasonably heavily nested area”. While leatherbacks are exclusive to Jahaji within MGMNP, the other three species nest on Tarmugli, Boat, and Twin Islands, where the Andaman and Nicobar Forest Department sets up seasonal camps to monitor and protect sea turtle nests during the nesting season.
Due to its high diversity and accessibility, MGMNP has been a key site for marine research. Institutions such as the Zoological Survey of India, Pondicherry University, Indian Institute of Science, Wildlife Institute of India, National Centre for Biological Sciences, Nature Conservation Foundation, Dakshin Foundation, and Andaman Nicobar Environment Team have studied the park’s terrestrial and marine ecosystems. Enigmatic animals such as the (1) king cobra and (2) dugong have been studied for genetic diversity and occurrence trends, respectively. Researchers have also conducted long-term monitoring of the dense tropical evergreen forests and assessed the effect of invasive species on these habitats. The marine park remains a vibrant space for both wildlife, researchers, and responsible visitors.
About the Authors
Adhith Swaminathan
has been working with sea turtles since the age of 11 and is currently working with Turtle Foundation conducting research on leatherback turtles in the Northeast Indian Ocean.
Nitya Prakash Mohanty
