01 June,2021 06:43 AM IST | Mumbai | Sukanya Datta
Representation pic
For marine biologist Harshal Karve, who works with the Mangrove Foundation of Maharashtra, coral is a charismatic creature that led him to pursue his PhD degree on the diversity of intertidal coral species of Mumbai. "I often wonder how a small, soft-bodied animal living in the sea secretes a calcium carbonate and forms a massive reef structure which protects the coastline and forms a complex ecosystem that supports an astonishing biodiversity, and which is eventually beneficial for humans," says Karve, pointing out the need to conserve this marine habitat. It is for this reason that marine experts across the world observe World Reef Day on June 1, to create change through education and engagement.
Verrill's cup coral. Pic/Pradip Patade
In Maharashtra, Karve asserts that the Malvan Marine Sanctuary is a small coral reef pocket located along the state coast. The Angria Bank is also a diverse coral reef off Sindhudurg. A few coral species have adapted and can be found in various intertidal areas along the shoreline, he adds. Here are some:
>> Flowerpot coral (Goniopora sp)
This beautiful looking coral is found in intertidal as well as subtidal regions along the coast. It has a long extending polyp.
>>Burnt cup coral (Cladangia exusta)
These are non-reef building types that lack zooxanthellae (a symbiotic algae). It is commonly found in intertidal areas.
>> Scroll coral (Turbinaria sp)
This is a hard coral. forming a massive disc, mostly found in Malvan Marine Sanctuary.
(Left) Abhishek Jamalabad and Harshal Karve
Abhishek Jamalabad, marine biologist at Marine Life of Mumbai (MLOM) and Coastal Conservation Foundation, shares that Mumbai has a number of hard and soft coral varieties. "The MLOM citizen project has documented at least eight species of hard coral along city seashores, and at least three soft coral along with an unresolved number of unidentified ones," he says. Mumbai, he adds, also has a variety of sea anemones and zoantharians, which are technically part of the hexacoral group alongside the hard coral.
> > Burnt cup coral (Cladangia exusta)
These are one of the commonest species of hard coral on the rocky shores of western Mumbai. They have tiny polyps (individual animals that make up the entire coral structure), about 4-mm across, but the colonies in many places are large enough to be seen easily. They get their name from the dark colour of the cup-like corallites.
>> Verrill's cup coral (Polycyathus verrilli)
Somewhat similar in structure to burnt cup coral, this is another species fairly widespread along the western shores. The polyps have an orangish brown colour, sometimes with a tinge of striking green.
>>False pillow coral (Pseudosiderastrea tayamai)
These are found at only a few sites in Mumbai, but found growing in some of the harshest conditions. The colonies grow on rocks and have a somewhat smooth, rounded appearance, with a honeycomb-like arrangement of polyps when seen up-close. Classified as âNear Threatened' by the IUCN.
>>Indian sea plume (Pseudopterogorgia fredericki)
Sea plumes, along with sea fans, sea pens, and their relatives, are the soft coral species found in Mumbai. They have polyps arranged on a flexible structure. They're found in various shapes, sizes and colours in Mumbai.
-Karve elaborates that increased population, pollution, unsustainable coastal development and climate change have become major threats to coral reefs. Rise in sea water temperature associated with the El Nino phenomenon affects symbiotic association of zooxanthellae which lives inside the coral and results in coral bleaching.
- Prachi Hatkar, a marine biologist and a project assistant with Wildlife Institute of India, informs us that the easiest way to help protect coral in our day-to-day lives is by controlling the use of single-use plastic. "This even includes the scrubs and face washes that we use which contain microbeads that aren't biodegradable," she adds.
- Jamalabad adds that coral species in a place like Mumbai remain understudied. So, one can explore the seashores, document the species first-hand and share it. "They can be used constructively for research, education and conservation by those accessing," he adds.
Coral is popularly thought of as a delicate creature that needs clear, undisturbed waters, says Jamalabad. "This is not true of all species. There are many which have developed the characters necessary to live in murky, turbid waters like those of Mumbai. Many species are also resilient, with the ability to recover after bleaching every summer. These are the kinds that we find across most of Mumbai's western seashores," he adds.
Karve says that the name is derived from Kanhoji Angre, who served as one of the most successful admirals under Maratha king Chhatrapati Shivaji. Angria Bank is a submerged plateau located 105 km offshore from the Konkan coast of Maharashtra. "It is suggested to have developed after the Holocene sea-level rise a few 1,000 years ago. Currently, this 2,011-km2 region ranges from depths of 20 m to 400 m and supports a large extent of coral reefs and associated flora and fauna. It has been identified by the Wildlife Institute of India as one of India's 106 Important Coastal and Marine Biodiversity Areas (ICMBAs)," he adds.
Karve explains that coral is a marine invertebrate which forms a colony of genetically and morphologically identical polyps. "Some coral species are solitary, forming a single polyp only. There are different types of coral such as hard and soft. They are also divided as reef building coral and non-reef building coral," he shares, adding that coral reefs are formed by coral polyps as they secrete layers of calcium carbonate beneath their body. "This ecosystem encompasses a variety of marine species such as molluscs, polychaetes, sponges, crustaceans, echinoderms, tunicates, cnidarians, fishes, etc," he adds.
