Angria Bank is a submerged plateau situated 105 km offshore from the southern coast of Maharashtra. This 2011 km2 region ranges from depths of 20m to 400m. It supports a large extent of coral reefs and algal habitats, spanning 650 km2 that harbours a high diversity of associated flora and fauna. The reefs also host diverse functional groups that are necessary for a stable ecosystem representing a resilient reef. This unique ecosystem makes it among the last strongholds of marine diversity in the northern Indian Ocean. Since Angria Bank supports such a high diversity of marine life, it is imperative to conserve the area.
Given its remote location within the country’s Exclusive Economic Zone (EEZ), only two biological surveys were conducted before 2019 at Angria Bank. The first was conducted by the National Institute of Oceanography (NIO) between December 1985 to October 1986. The second survey was conducted jointly by NIO, the United Nations Development Program (UNDP), the Global Environment Facility (GEF) and the Ministry of Environment, Forests and Climate Change (MoEF&CC) in 2014. Both surveys helped build a baseline understanding of the area’s marine life, reporting nearly 60 species of algae, 20 species of hard coral, 18 species of fish and 32 species of invertebrates.
In order to assess the current status and to build on the existing knowledge of the existing flora and fauna of Angria Bank, WCS-India, with support from partner institutions conducted a third survey of the region from the 18th to 30th December 2019.
The vessel used for the expedition was Fishery Oceanographic Research Vessel Sagar Sampada (FORV Sagar Sampada) for the expedition. The Mangrove Cell- Maharashtra Forest Department, the Indian Institute of SCUBA Diving and Aquatic sports, India SCUBA Explorers and Jolchhobi Films also partnered with WCS-India on the venture.
This site visit included:
1) Biological assessments: To assess the benthic life, we conducted underwater transects and also laid quadrats along these transects. Additionally, to help record pelagic birds and surfacing megafauna like cetaceans and marine reptiles, we conducted boat-based surveys around Angria Bank.
2) Depth profiling: Using the electronic depth profiling (EDP) facilities aboard the FORV Sagar Sampada, we collected information on the depths at different locations along the bank.
3) Documenting the ecosystem: We enlisted the services of Jolchobbi Films to help us document the region through photographs and footage.
The preliminary results of these surveys suggest a rich diversity of corals consisting of 29 genera and 39 species. These comprised scleractinians (hard corals) and alcyonacea (soft corals), represented by massive, submassive and plate coral life forms. The reefs showed no evident signs of bleaching (an aftermath of climate change and other stressors), physical damage or other forms of stress indicating excellent reef health and resilience in the face of climate change.
The team also observed 123 species of fish. Important functional groups were represented by various trophic guilds: 1) Piscivores: predators - reef sharks, groupers; mesopredators - moray eels, sea snakes, trevally, jacks; 2) corallivores – butterflyfish 3) macro-invertivores - triggerfish, wrasse, hawkfish, angelfish; 4) algal and plankton feeders- surgeonfish, fusiliers, damselfish etc.
Furthermore, the expedition members detected 43 species of invertebrates such as thorny sea stars, swallowtail slugs, and comb jellies during the surveys. The presence of these thriving trophic guilds serve as indicators of stable ecosystem functioning.
While no marine mammals were spotted during this survey at Angria Bank, four species of dolphin and potentially one species of whale were sighted within an area to the South of the bank. Further, the western edge of the region drops steeply to a depth of over 400m, forming a barrier for nutrient-rich upwelling from the depths of the Arabian Sea. This area could thus potentially support multiple species of marine mammals.
Angria Bank is thus a critically important marine area in the country. The area harbours rich coral reef (listed under Schedule I of WLPA) and is also hypothesised to provide a resting habitat for the Critically Endangered species of sawfish (listed under Schedule I of WLPA) and large myctophids (lanternfish) aggregations, making it an important fish spawning ground. Such habitats are critical as they provide security towards future population stocks.
Having visited the area, several expedition participants suggest that Angria Bank is possibly the most undisturbed among India’s marine ecosystems and will stand to benefit immensely from protection. Some of these divers included experienced scientists who have surveyed reefs across Indian waters for over a decade. According to their accounts, the reefs like Angria Bank are unlike any other in the country, in terms of both- reef health and faunal diversity. Given the rate of habitat destruction across the country, it is imperative to put in place adequate measures to protect the region.
The WCS-India Marine team
Going forward, WCS-India aims to assist the Government of India in protecting Angria Bank in the long-term, by aiding the relevant agencies in developing an effective management plan for the region, while building capacity within existing enforcement agencies and local stakeholders towards ensuring compliance.