In which type of environment is hypoxia most prevalent?

Hypoxia is most prevalent in coastal and estuarine waters due to the natural processes occurring in these environments, particularly in areas where excess nutrients, often from agricultural runoff, lead to eutrophication. This nutrient enrichment stimulates the growth of phytoplankton, which, when they die and decompose, consume large amounts of dissolved oxygen in the water. As oxygen levels diminish, it creates conditions unsuitable for many aquatic organisms, leading to a hypoxic or even anoxic environment.

Coastal and estuarine regions are particularly vulnerable because they serve as transition zones between land and open ocean, often receiving higher nutrient inputs from various sources, including rivers and human activities like farming and urban runoff. This biochemical cycle, coupled with factors such as water stratification and temperature variations, increases the likelihood of hypoxia in these waters, making them hotspots for this phenomenon. In contrast, upland forests, desert regions, and mountain lakes have different ecological dynamics that do not typically lead to the conditions conducive to hypoxia.