What is a key function of estuaries in ecosystems?

Estuaries play a crucial role in ecosystems primarily due to their ability to support high biodiversity and nutrient richness. These areas, where freshwater from rivers meets and mixes with saltwater from the sea, create unique environments that provide habitats for a wide variety of species, including many fish, birds, and other wildlife. The mixing of waters leads to a rich nutrient environment, supporting primary production and forming the base of the food web.

High nutrient levels foster the growth of vegetation, such as salt marshes and mangroves, which further enhance habitat diversity. The complex structures formed by these plants provide shelter and breeding grounds for various organisms, contributing to high levels of biodiversity. Additionally, estuaries are important nursery grounds for many marine species, as they offer protection and abundant food resources during their early life stages.

In contrast, the other options reflect misconceptions about estuarine functions or describe less significant attributes. For instance, estuaries are not limited to marine species; they also support numerous freshwater organisms, making them highly diverse ecosystems. While estuaries can experience pollution, they are not defined by the concentration of pollutants but rather by their ecological benefits. Although they can help buffer against storms, this function is secondary compared to their role in sustaining diverse biological