GS2 PYQ (Mains Answer Writing): Dead Zones on Marine Ecosystems | Geography for UPSC CSE PDF Download

What are the consequences of spreading of ‘Dead Zones’ on marine ecosystem? (UPSC GS1 Mains)

Dead zones are low-oxygen, or hypoxic, areas in the world’s oceans and lakes. Because most organisms need oxygen to live, few organisms can survive in hypoxic conditions. That is why these areas are called dead zones. Dead zones in the coastal oceans have spread exponentially since the 1960s and have serious consequences for ecosystem functioning.
Effects of dead zones on marine ecosystem: 

• An ocean dead zone is an invisible trap that there is no escaping from for marine life. Fish can’t detect dead zones before entering the areas. Unfortunately, once fish wander into a dead zone, it’s hard to escape and survive. The oxygen shortage causes the fish to lose consciousness and die shortly after. Other sea dwellers, such as lobsters and clams, are also unable to get away because they naturally move slowly. 
• Fish suffer greatly from dead zones because the extreme changes in the oxygen level changes their entire biology. Their organs become smaller, meaning they can’t reproduce or function in the necessary ways that allow them to flourish. The females are unable to produce as many eggs and the males can’t properly impregnate the females to keep the species alive. 
• By depriving organisms of sunlight and oxygen, algal blooms negatively impact a variety of species that live below the water’s surface. The number and diversity of benthic, or bottom-dwelling, species are especially reduced.  
• The less biodiversity that exist underwater, the more the balance of the entire ocean is disrupted. This also leads to economic instability for local fisherman. 
• Elevated nutrient levels and algal blooms can also cause problems in drinking water in communities nearby and upstream from dead zones. Harmful algal blooms release toxins that contaminate drinking water, causing illnesses for animals and humans. 
• Algal blooms can also lead to the death of shore birds that rely on the marine ecosystem for food. Wading birds, such as herons, and mammals, such as sea lions, depend on fish for survival. With fewer fish beneath algal blooms, these animals lose an important food source.  Scientists have identified 415 dead zones worldwide. 
• Conservation of the marine ecosystem is crucial for its survival and its success hinges on the collaborative spirit of cities, farmers, agri-business and policy makers to embrace science-based solutions, both on the ground and at the policy level. 
• By following these simple methods of keeping the environment clean and keeping communities aware of methods of industrial practices used by factories, we can ultimately draw an end to dead zones and provide a better environment for the ocean, animals and people that live in these areas.

Topics covered - Marine Ecosystems, Dead Zones, Oceanography