Dead zones are low-oxygen areas in the world's oceans and large lakes. They are caused by "excessive nutrient pollution from natural & human activities'.
These oxygen-depleted areas, often caused by excessive nutrient runoff, disrupt the delicate balance of marine life. First, dead zones lead to massive fish kills and the decline of commercially important fish species, impacting fisheries and food security. Additionally, the disruption of the food chain affects marine biodiversity, endangering various species. As the water heats up from climate change, there are more dead zones that are forming because of eutrophication. Eutrophication is how the underwater environment reacts to pollutants from runoff that comes from the land and leads to the overabundance of nutrients, encouraging the overgrowth of algae.
Dead zones can result in harmful algal blooms, some of which produce toxins harmful to both marine life and humans, causing health issues. The economic consequences of this ecological disturbance are substantial, as tourism, recreation, and industries dependent on healthy oceans can suffer.
The algae overgrowth blocks the light from the sun. Plants go through photosynthesis underwater and they also produce carbon for breathing. Animals need these plants to live underwater just as they do on land for oxygen. Low oxygen levels recorded along the Gulf Coast of North America have led to reproductive problems in fish involving decreased size of reproductive organs, low egg counts and lack of spawning.
Furthermore, the release of greenhouse gases from dead zones contributes to global climate change. Addressing these dead zones requires effective nutrient management, sustainable agricultural practices, and international cooperation to mitigate their far-reaching consequences on marine ecosystems and the interconnected web of life.