Are our oceans going breathless?

Dissolved oxygen in water is essential for the survival of fish and other aquatic organisms. Levels that are too high or too low can harm aquatic life and affect water quality. There are regions in oceans across the globe where the concentration of dissolved oxygen can be so low that marine animals can suffocate and die, and as a result, these regions are often called dead zones. A new study by the conservation group the International Union for the Conservation of Nature (IUCN) has revealed that the number of dead zones has quadrupled in the last half-century – from only 45 in the 1960s to as many as 700.

Citing climate change and increase in nutrient pollution as the causes, the IUCN has warned that many species of fish, including sharks, tuna and marlin are at particular risk. These fishes are sensitive to low levels of the life-giving gas due to their large size and energy demands.

The report on ocean oxygen loss concluded that deoxygenation is already altering the balance of marine life to the detriment of species across the food chain. The biomes that supports about a fifth of the world’s current fish catch are formed by ocean currents usually bring oxygen-poor water to coastlines. So, these areas are especially vulnerable to even tiny variations in oxygen levels, it said.

On currently trends, oceans are expected to lose 3-4% of their oxygen globally by 2100. Most of that loss is predicated to be in the upper 1,000 mt – the richest part of the ocean for biodiversity.

 

Picture Credit : Google