Coral reefs in the Gulf of Mannar off the coast of Tamil Nadu in southern India, seem to be recovering after a mass coral bleaching event in 2017. At the start of 2015, the US National Oceanic and Atmospheric Administration declared that the corals across the globe had entered a mass bleaching event. This was the third time a global-scale bleaching of corals was occurring, after 1998 and 2010. In 2016, a survey of Gulf of Mannar done by scientists from Suganthi Devadson Marine Research Institute in Thoothukudi (earlier called Tuticorin), Tamil Nadu revealed that 16.2% corals had died. Of the remaining corals, close to one-fourth (23.9%) had bleached.
Coral bleaching occurs when the water is too warm, which causes the corals to expel their symbiotic algae (zooxanthellae) and turn white. Corals can survive a bleaching event, but they are left under more stress and are subject to mortality after a bleaching event.
Signs of recovery
At the end of 2017, the outlook for the Gulf of Mannar corals looked pretty grim. Luckily, however, 2018 has brought some good tidings and corals are showing signs of recovery. TP Ashok Kumar, the wildlife warden of the Gulf of Mannar Marine National Park, confirmed that the corals are looking good at present.
On the eastern coast of India, the Gulf of Mannar is located between the island of Rameswaram and Thoothukudi. A cluster of uninhabited islands in the gulf are home to an expansive reef population. In 1986, the reef area was declared as the Gulf of Mannar Marine National Park, which comprised 23 islands, two of which are now submerged. The remaining 21 are divided into four island groups, Mandapam in the North, followed by Keelakarai, Vembar and the Thoothukudi groups going South. The entire reef region is quite shallow, with depths ranging between just three to six metres.
When the Suganthi Devadson Marine Research Institute researchers were surveying coral damage in 2016 here, they found that maximum coral bleaching and death had happened in Mandapam. Keelakarai corals were next and the Thoothukudi group had faced the least damage. Now, when corals are beginning to recover, the Thoothukudi group is performing better.
“There are no clear or direct answers for why the Thoothukudi group has better resilience, but a “combination of factors may be responsible,” said JK Patterson Edward, director of Suganthi Devadson Marine Research Institute. “One of the reasons could be the greater depth of the Thoothukudi region, which ensures this group of islands receives a lower intensity of sunlight. Another reason could be that most of the rehabilitation work happens in Thoothukudi region.”
Patterson also drew attention to the pace of recovery which is much slower this time in comparison to 2010, when the second global bleaching happened. This time, because bleaching was sustained across a longer period, even the juvenile corals were damaged, making it harder for the corals to regenerate.
Though early signs of recovery from bleaching are visible, there are other hurdles that may come in the way of a full recovery. There are problems of untreated sewage discharge, coral diseases, invasive species and unsustainable fishing practices hampering the recovery of the corals. Several of these threats are a result of the way people interact with marine resources.
Threats prevail
Take for example, the fishing practices. As population in the area has grown, the catch sizes have gone down. The Gulf of Mannar has seen an explosion in the population and the pressure on the ocean has increased.
“Earlier fish used to come to us, now we have to search for them,”Amaldas a local fisherman from Thoothukudi said. Having started fishing at the young age of 13, Amaldas who is now 42, admitted to not being able to fend for his family because of the diminishing catch.
In their desperation to make ends meet, many fishermen are willing to adopt fishing methods that fulfill their requirements in the short term but are not sustainable Practices like beach seine and trawling are becoming common. These are not only harmful for juvenile fish but also damage the corals. Trawlers have huge nets that pluck the corals out from the substratum.
RL Laju, senior research fellow from Suganthi Devadson Marine Research Institute, has been surveying the fish living amidst corals every month since 2011. Recently, he noticed a new kind of fishing technique catching on in the region. Called trap fishing, in this method, the fishermen create traps to catch a single type of fish called parrotfish. Parrotfish provide an important ecosystem service as coral cleaners. They eat the algae growing on the surface of corals. Traditionally, fishermen haven’t had any particular affinity to these fish but now, export-related demand is driving them to create special traps for these fishes.
Another fast emerging threat to the Gulf of Mannar corals is from Kappaphycus, a seaweed cultivated at the sea bottom. Kappaphycus is an important source of gelatin and fetches a good price when sold.
“This seaweed was introduced from the Philippines to the Gulf of Mannar to provide an alternative source of livelihood to the fishermen”, said Laju. Unfortunately, it is now becoming an invasive species. It invades the corals and suffocates them to death.
“Around two to three square kilometres of area in the sea bottom here is now invaded by this species”, said Patterson.
Measures are being put in place to check the growth of the damaging the seaweed. The wildlife team at Gulf of Mannar Marine National Park has been involved in operations to remove the seaweed growing at the sea-bottom. Several fishermen have also joined them in the rescue operation. Wildlife warden Kumar is confident that the right way out of this mess is to not “enforce rules on the fisherfolk, but to educate them about the consequences.”
Fishermen in the region are well-aware of the importance of corals, especially since the 2004 Indian Ocean tsunami. In 2004, the the tsunami wreaked havoc across the eastern coast. The part of the coast in the reef region though was not as damaged as the rest of the coast. This brought about a massive change in people’s outlook towards corals.
They could see that the reefs had protected them and were ready to return the favour. After the tsunami, no one wanted to mine corals. The government also introduced a ban on coral mining in 2004. In the 15 years since, coral mining has completely stopped.
However, while the fisherfolk are not deliberately tearing off corals from the ocean bottom, they are not cognizant of the impact when corals break off or die because of fishing. Driven by catch shortages, the fisherfolk are readily adopting fishing techniques that land up killing juvenile fish and corals.
Arjun Motha, who runs an eco-tourism venture in the Gulf of Mannar, has employed many fishermen who have given up fishing because it is no longer viable. “Appropriate control measures can save the fishes and corals,” he said. “Young people here can no longer look at fishing as a profession, at least the sustainable kind, as a profession. We need to create options such as organic fish farms that are a win-win for the local communities as well as the marine resources, he suggested. As long as these options are not available, they will continue to depend on the ocean and overexploit its resources when the need arises.”
For most of these local people, the ocean and the fisheries is part of their DNA. Their lives are deeply interdependent. And corals, have a special place in the marine ecosystem. They cover less than 1% of ocean floor but support 25% of all marine life. It is perhaps for this reason that Ashok Kumar said, “if we can protect the corals, we can protect all our marine resources.”
The question remains, however, what will be the cost of this conservation? Can we create solutions that protect the corals and at the same time protect the livelihoods of fisherfolk like Amaldas?
This article fist appeared on Mongabay.
