Nutrient loading, often caused by agricultural runoff and urban waste, can lead to severe effects on marine ecosystems. High levels of nutrients, particularly nitrogen and phosphorus, result in eutrophication, which triggers excessive algal blooms. These blooms can deplete oxygen levels in the water, creating dead zones where aquatic life struggles to survive. Additionally, harmful algal species can produce toxins, impacting fish, marine mammals, and even human health. Overall, nutrient loading disrupts food webs and deteriorates the quality of marine environments, threatening biodiversity and fishery productivity.