What type of problems can mat-forming algae cause in aquatic environments?

Mat-forming algae, such as those that create dense mats on the water's surface, can significantly block light from penetrating the water column. This reduction in light availability affects the growth of other aquatic plants, including beneficial submerged vegetation, which rely on sunlight for photosynthesis. When these plants cannot receive adequate light due to the covering of algae, it can lead to a decline in their populations, disrupt the aquatic ecosystem, and cause further ecological imbalances.

In addition to light blockage, dense mats of algae can also alter the physical and chemical properties of the water, potentially leading to oxygen depletion during decomposition processes, which can negatively impact fish and other aquatic organisms. This chain reaction often results in poor water quality and can create an environment that favors the growth of more problematic species, ultimately harming overall biodiversity in the aquatic system. In contrast, options related to increased oxygen levels, reduction in nutrient availability, and clean water do not correctly address the ecological consequences caused by mat-forming algae.