Which of the following is a key benefit provided by coastal marshes?

Coastal marshes play a crucial role in the health of marine ecosystems, and one of their key benefits is their ability to filter pollutants from water. This natural filtration process helps improve water quality by trapping sediments and absorbing excess nutrients, such as nitrogen and phosphorus, that can lead to issues like algal blooms. By maintaining cleaner water, coastal marshes not only support biodiversity but also enhance the overall functioning of coastal and marine environments.

In contrast, while coastal marshes can support the fishing industry and recreational activities, those aspects are secondary benefits rather than primary functions of marsh ecosystems. The significance of coastal marshes extends beyond just economic and recreational uses; they serve essential ecological roles. Their use for industrial development contradicts the nature of marshes, as such activities often lead to habitat destruction and degradation, undermining the benefits they provide.