Seas are an amazing repository of life forms and it is believed that some of the stunning aquatic species are yet to be discovered. Sadly, these life forms are now falling prey to global warming and pollution

The spectre of global warming is now reaching the deepest and coolest parts of the planet and its oceans. Considered the life blood of the Earth, the oceans are an amazing repository of life forms and it is believed that some of the stunning aquatic species are yet to be discovered. Sadly, these are now falling prey to global warming and pollution as the flora and fauna in the marine ecosystem have long been at the receiving end of man-made malaise. A case in point is the Great Pacific Garbage Patch, a man-made floating island of marine debris comprising mostly plastic, weighing over 700,000 tonnes, in the North Pacific Ocean.

Also known as the Pacific trash vortex, this marine debris comprises the Western Garbage Patch near Japan and the Eastern Garbage Patch between Hawaii and California. Oceanographers and ecologists recently discovered that about 70 per cent of marine debris actually sinks to the bottom of the ocean and ruins the marine ecosystem.

Closer home, the Indian coastline that supports an ancient and diverse coral reef system is fighting a different battle. Corals are referred to as underwater rainforests because of the important role they play in supporting marine life and biodiversity. They are also vital for fisheries, tourism and as a repository of medicinal, agronomical and industrial products. Based on a recent study, a team of Indian researchers has warned that rising sea temperatures could put these fragile underwater systems in peril. They analysed information from the National Oceanic and Atmospheric Administration’s Optimum Interpolated Sea Surface Temperature database from 1982 onwards and found that three mass bleaching events occurred in 1998, 2010 and 2016, impacting coral reefs in the Andaman, Nicobar, Lakshadweep, Gulf of Mannar and Gulf of Kutch.

Oceans are massive sinks for greenhouse gases. However, as they absorb them, the oceans warm up and there are changes in seawater chemistry. Corals are sensitive to temperature changes, which affect photosynthesis and calcification of their structures, making them prone to diseases and even death. Sea algae and corals share a symbiotic existence and when seawaters turn warm in summers and remain so for more than 28 days, the corals experience thermal stress. Due to this, they expel the zooxanthellae algae residing in their tissues and turn colourless, say the findings published in the Current Science journal. Although coral reefs are known to recover from bleaching in a decade or two, its severity can overwhelm them and hamper their ability to recover.

Coral bleaching is not specific to Indian coasts. The most extensive coral bleaching event from 2014 to 2017 affected reefs across the world, including the Great Barrier Reef in Australia, where the damage was intense and also those along the east coast of Africa, where the intensity of destruction was slightly less. Seychelles was the worst-hit, followed by Madagascar, while parts of Mauritius, Kenya and Tanzania were badly impacted. If bleaching continues for an extended period, the corals eventually die.

Coral bleaching and mortality exacerbated by climate change are the biggest threats to oceanic biodiversity as reefs provide the perfect place for marine life to thrive, especially fish. The fallout of bleaching and coral death is a rise in the growth of fleshy macro algae in reefs, which does not allow corals to revive by taking up their space. Interestingly, depletion of corals also seems to have a detrimental impact on tourism. For instance, when intense coral bleaching occurred in Africa, it hit the scuba diving industry and tourism badly.

According to a World Bank estimates, the African tourism industry reported losses amounting to $2.2 million in Zanzibar and $15.09 million in Mombasa. Even Seychelles has lost a considerable amount of its coral reefs and the country’s profits from dive tourism have dipped.

India must learn from these global debacles and rush to save its coral reserves from destruction. This will not only preserve the environment and oceans but also protect the tourism industry and the lives attached to it.

(The writer is an environmental journalist)