Biological Activity

Warm, low-latitude climates encourage the growth of lush vegetation in comparison to relatively colder, high latitude climates. For example, in warm coastal climates thick, extensive platforms of mangrove forests or salt-tolerant grasses can develop if the substrate is suitable for the development of good root zones, and the plants are not exposed to high energy wave or tidal conditions that can uproot them. Although a wide range of coastal plant species exist even within high-latitude coasts, the species that occupy warm climates will tend to be more organically productive with longer growing seasons.

Along coasts where vegetation is highly productive, this vegetation can constitute a significant contributor to the coastal sediment budget. When plants of the coastal zone die, the fragments of the plant, also known as organic detritus, can accumulate and help incrementally add elevation to the land surface. In some coastal areas this process of accumulating organic debris derived from the plants has been suggested to be a major contributor to the health of coastal marshes and their ability to maintain a suitable elevation above sea level as sea level rises.

Vegetation plays another important role along some coasts because extensive root systems help to stabilize environments such as coastal marshes and dunes and can reduce the amount of wave and wind erosion that can take place. The presence of extensive coastal plant communities also can help reduce the destructive power of storms surges and tsunamis to inland areas and coastal infrastructure because the plants act to buffer the energy of these phenomena to the more inland areas.

Some coasts are also fringed by coral reefs. The most extensive and largest reefs are located in warm ocean waters because corals are temperature dependent with optimal growth of most coral reefs taking place in low-latitude climates where ocean waters are warm. Corals produce their hard structure out of the mineral calcium carbonate, as do shelled organisms such as clams, oysters, and snails. All of these organisms can be broken apart or fragmented by marine currents and ultimately contribute sediment to a coast. In some areas of the world the beaches wholly consist of broken coral and shells.