Coastal habitats—areas both along and close to marine shorelines—are vital ecosystems. They help mitigate the impacts of climate change, for example by storing carbon and buffering the effects of floods and storms, and provide a range of other services, including serving as nurseries for a range of species and absorbing runoff from farming.
Conserving these habitats is vital for protecting shorelines, feeding and sheltering marine life, and lessening the effects of climate change, an effort that must also include reducing global carbon emissions. Here’s a deeper dive into four types of coastal habitat: mangroves, salt marshes, seagrass meadows, and coral reefs.
A recognizable feature of some mangrove trees are their roots—tangled, clumped together, and growing above the shorelines. These roots buffer coastlines from storm surges, tides, waves, and currents; make ideal nursery grounds for groupers, snapper, and some species of sharks; and provide protection for smaller fish from their predators. Mangrove forests can store three to five times more carbon in their soil than tropical rainforests. All 80 or so species of mangrove trees are found in tropical and subtropical equatorial regions.
Seagrass is exactly what its name suggest—plants growing underwater, with roots, stems, and leaves. There are 72 species, and one or more of them grows in nearly every coastal ecosystem, from the Arctic Circle to the tropics. These critical habitats also serve as nursery grounds for many valuable fish and wildlife species, and play a key role in maintaining water quality. Similar to mangrove forests, seagrass also helps lessen the impacts of severe weather, reduces erosion, and mitigates the effects of climate change by absorbing about 10 percent of the total estimated organic carbon sequestered in the oceans each year.
Salt marshes are found worldwide, most commonly in temperate regions. These unique coastal areas are often flooded by saltwater as tides come in and are home to a range of species from fish to invertebrates and birds. Many species of shrimp, crab, and fish also use these areas as nursery habitat, making marshes an important contributor to fisheries and local economies. By absorbing rainwater and reducing flooding, marshes also serve as natural infrastructure to protect coastal communities. Salt marshes are also recognized as effective sinks for carbon, a characteristic they share with mangroves and seagrass.
When most people hear “coral reef” they think of the tropics, but these habitats are found throughout the ocean, even in the Antarctic. The most recognizable corals are those that form hard calcium carbonate skeletons using the chemicals found in seawater. However, there are soft coral species such as sea whips and sea fans. The biggest coral reefs are thousands of years old and usually thrive in warm, shallow water where they receive plenty of sunlight. Much like seagrass meadows, mangrove forests, and salt marshes, coral reefs are home to numerous species. In addition to providing critical nursery and rich feeding grounds for a wealth of marine species, they also help to buffer coastlines from severe storms and flooding.
Simon Reddy directs The Pew Charitable Trusts’ coastal wetlands and coral reefs project.