We at Poornam Ecovision Foundation work on different ventures with THE goal of sustainable future of the ‘Only One Earth’ we have. How can we think of a sustainable future without a sustainable Ocean that covers 71% of the Earth’s surface, produces 50% of the Oxygen we breathe, and absorbs 40% of the Carbon emissions we produce! 8th June every year is celebrated as World Oceans Day. The United Nations General Assembly started celebrating this day since 2009 in order to raise global awareness amongst the common man regarding the innumerable benefits we derive from the oceans and our individual and collective duty to use it as resource sustainably. This year’s theme for World Oceans Day was ‘Revitalization: collective action for the ocean’, which invited States, Civil Society, Scientific bodies, industry, private sectors as well as inter-governmental bodies to contribute to reviving our oceans.
When common man thinks of oceanic environmental issues, all that he can think of is pollution; plastic pollution being the latest hot topic. Let us delve a little deeper into understanding what we mean by ‘Our oceans are dying’; or why is there a need for ‘revitalising our oceans’. Aquatic life, popularly fish are the easiest and commonly tangible measure of the oceanic health. So, let us look as status of fish in our oceans. Recent news highlighted increased events of fisherman complaining of no fish catch at high sea. Since decades coastal fishing communities have lost livelihoods due to dwindling coastal fish. This has caused them loss of local and traditional food source too. So, depleting fish catch is not only an economical issue but also a cause of dietary and occupational switch and blow to traditions. Fish also serve as a cleansing mechanism of the oceans. They feed on algae which can otherwise smother coral reefs and also cause rapid depletion of oxygen.
The greed of man to increase fish catch to meet the ever-increasing demand of the fish-eating population has led to mechanised fishing that use trawlers which scrape/dredge the sea bed for increased fish catch. This has led to over-fishing, a process in which the rate of fishing exceeds the rate of their reproduction. Sea beds serve as breeding grounds and nurseries of several organisms in the aquatic food chain and dredging causes long term damage to this habitat. Non-targeted species like the turtles, mammals, eggs, larvae and non-commercial fish too get harvested which are killed and dumped back into the ocean as fishery waste. It is worth thinking what happens when one part of the food chain is excessively removed from the food chain as well as what happens to the lower and higher organisms which depend on them! Indian traditional scientific knowledge regarding the importance of sustainable fishing is the basis of observing the holy ‘Sraavan Maas’, where fish was not eaten. It is driven by the idea, that the monsoon season is the breeding season when fishes repopulate and a break in fishing allows healthy increase in fish population. Indian government imposes a systematic ban on mechanised fishing from 1stJune to 31st July along the west coast of India and 15th April to 15th June along the east coast of India every year, to promote sustainable fishing all throughout the year.
Some of the most popular videos on the oceans on social media feature mass beaching of fishes, whales, dolphins and even penguins! Common population envisages marine pollution as dumping of untreated municipal and industrial waste, oil pollution and plastic pollution which adds toxic, poisonous material into our oceans causing fishes and aquatic organisms to die. The realm of oceanic pollution is beyond this! Oceanic life needs oxygen; healthy oceans typically have 7 to 8 mg/litre dissolved oxygen. Larger the organism, higher is its requirement for oxygen. Life forms die or start to migrate if the concentration of dissolved oxygen drops below 4 mg/litre. Concentrations less than 0.2 mg/litre are hypoxic or anoxic conditions, also known as Oxygen Minimum Zones (OMZ) in the oceans. Excessive supply of fertilisers and nutrients like nitrates and phosphates to the coastal oceans through rivers, soil runoff due to deforestation and agricultural runoff from land has led to expansion of OMZ all over the globe in the recent past. Excess nutrients cause fast consumption of oxygen for different biological and chemical processes within the ocean leading to formation of oxygen minimum zones. So, what appears to be just innocent, religious offerings or disposal of nirmaalyain the ocean by us, actually contributes to rapid depletion of oceanic oxygen and provides an explanation to reduced fish catch and also mass beaching of organisms.
Climate change is another threat to our oceanic life as well as our fishery which contribute to our economy as well as food-stock. Excessive heating of the oceans along the tropical countries is causing fish to migrate to cooler latitudes, thus making the temperate richer countries richer and the poorer tropical countries poorer. Coral reefs, the most biodiverse and ecologically-economically important, marine ecosystems which used to be found only between 30 degrees North and South latitudes are now being found even in the temperate zones. These are bioindicators of change in the oceanic environment as a response to thermal pollution. One major source of thermal pollution causing changes in current patterns are release of warm waters from thermal power plants and nuclear reactors into the ocean.
As we continue to pump more and more carbon-dioxide into the atmosphere, the oceans are absorbing it causing the oceans to acidify. This reduced pH of the oceans is causing skeleton of marine organisms to dissolve and also affecting reproduction in organisms. This directly impacts the marine food chain and is also a major cause of depletion of food for fishes.
With only 20% of the world ocean mapped, we know much less about the ocean than we know about Space. Oceans hold solutions to life on Earth and are also the most easily accessible store house of future resources when we run out of them on land. If we wish to sustain mankind, its high-time we make our oceans sustainable!
-Dr. Rajani Panchang
UGC FRP Assistant Professor
Secretary, Palaeontological Society of India Pune-Mumbai Chapter