What process is primarily caused by excessive nitrogen and phosphorous in water bodies?

Eutrophication is the process that occurs when excessive amounts of nitrogen and phosphorus are introduced into water bodies. These nutrients often originate from agricultural runoff, wastewater discharge, or industrial pollutants. When they enter the water, they stimulate the rapid growth of algae, a phenomenon known as algal blooms.

As these algae proliferate, they can deplete oxygen levels in the water when they die and decompose, leading to hypoxia, a condition where there is insufficient oxygen to support aquatic life. This decline in oxygen can result in the death of fish and other organisms, disrupting the entire ecosystem. The excessive nutrient enrichment can also result in harmful algal blooms that produce toxins, further impacting aquatic species and potentially affecting human health.

In contrast, bioaccumulation refers to the gradual accumulation of substances, such as pesticides or heavy metals, in an organism over time, which is not directly linked to nutrient levels in water. Habitat fragmentation involves the breaking apart of ecosystems, often due to human activities like urban development, and is unrelated to nutrient compounds. Acidification typically describes a decrease in pH levels in water bodies, largely due to increased CO2 levels, leading to changes in aquatic chemistry that do not correlate directly with nitrogen and phosphorus levels.