By Janhavi Lokegaonkar, Research Associate, Maritime History Society
It happens quite often that when an aerated drink is poured, we do not consume it all at once. Sip by sip as we devour on a drink and reach half the glass, one finds that the fizz is all gone leaving just sweetened, flavoured water. Don’t we all hate such flat soda? This is because when the drink (liquid) becomes warmer it holds lesser gas as compared to the cold ones. Now, let us consider the ocean water to be that drink and the Indian Ocean, being tropical weather having warmer water paving way to creating of Dead Zones.
Hypoxia more commonly known as a ‘Dead Zone’ refers to a reduced level of oxygen in the water. As most marine life either dies or in case of movable marine creatures that just abandon the area, it is often referred to as a “dead zone” owing to its barrenness and inhospitable environment. Due to limited exchanges with the atmosphere and the warm water, the tropical regions in the Indian Ocean are susceptible to low oxygen levels as compared to the higher latitudes, where the seas can take in and dissolve more oxygen from the atmosphere. And, the colder ocean waters are prone to contain more oxygen.
Dead zones can also be linked to global warming and they are increasing at an alarming rate in both size and number. They occur in coastal areas around the nations and no part of the country or the world is immune to this. Although, dead zones can occur naturally, but scientists are concerned about the areas created or enhanced by human activity.
There are many factors that combine to create dead zones: physical, chemical, and biological. It is noted that the nutrient pollution is the primary cause of those zones created by humans. Overgrowth of algae is stimulated due to excess nutrients that run off land or are piped as wastewater into rivers and other water-bodies, which then sink in and decompose in the water. This decomposition process causes the depletion of oxygen supply to healthy marine flora and fauna. In short, Dead zones contain no oxygen and are also associated with nitrogen depletion, which means they are void of most marine life.
In the Indian Ocean region, a dead zone has been identified in the Bay of Bengal. But, in this aspect, the dead zone identified in the Bay of Bengal has confused many scientists. It is a subject of utmost curiosity and research. The hypoxic zone in the Bay of Bengal has long stood as a mystery because a lot of research suggest no oxygen in the waters, but, despite this, there has been no indication of nitrogen loss as seen in other ‘dead zones’ of the global ocean. It remains a mystery and a heated topic of research and debate amongst the scientists and scholarship as to why it is different than other dead zones.
A balance in the ecology is needed. Human intervention has already caused a havoc in the course of nature’s cycle. The problems that we face is a result of our own actions. Population explosion has lead to pollution, over-fishing, agriculture that needs fertilizers that in turn spoil the environment all are causes to the slow death of the hospitable zones of the marine creatures and flora.
Source Image 1: shutterstock
Source Image 2: https://www.deccanherald.com/content/587379/huge-dead-zone-found-bay.html