What is one of the major problems caused by nutrient overload in aquatic systems?

One of the major problems caused by nutrient overload in aquatic systems is reduced aquatic biodiversity. When nutrient levels, particularly nitrogen and phosphorus, become excessively high due to sources such as agricultural runoff or wastewater discharge, they can lead to harmful algal blooms. These blooms can deplete oxygen in the water and block sunlight from reaching underwater plants, disrupting the ecosystem. As a result, many aquatic species, especially those that depend on specific habitat conditions, may struggle to survive or reproduce. This decline in species diversity can have cascading effects, altering food webs and the overall function of aquatic ecosystems, ultimately making them less resilient to changes and stresses.

The other options, while related to aquatic ecosystems, do not directly address the connection between nutrient overload and biodiversity loss in the same impactful way. For instance, increased sediment accumulation and enhanced water filtration might not occur solely due to nutrient overload and can be influenced by various environmental factors. Lower water temperatures generally relate more to climatic changes than to nutrient levels.