When looking out over coastal waters across much of our planet, one can often see large areas that appear darker than their surroundings—a possible sign of seagrass meadows, which play a critical role in the health of our ocean. Seagrasses evolved millions of years ago when flowering plants on land took up residence in the sea. Now, the estimated 72 species of seagrass fringe every continent except Antarctica.
In honor of Seagrass Awareness Month, observed every March, here are seven reasons this important ecological resource deserves protection:
1. Seagrasses are diverse.
With over 70 species, seagrasses are a diverse group of marine flowering plants that exhibit a range of characteristics. While some have ribbon-like leaves that resemble grass, some look like other plants. For example, the tallest seagrass species—Zostera caulescens—is native to the shores of northeastern Asia and can grow leaves as long as 7 meters (roughly 23 feet)!
2. Seagrasses are “ecosystem engineers.”
Seagrasses can create or significantly modify their environment and provide microhabitats that would not otherwise exist. For example, they take in carbon dioxide—improving chemical conditions for species affected by ocean acidification—and release oxygen, which marine animals need to breathe. The matted roots of seagrass stabilize ocean sediments, and the plant’s canopy provides shelter and nursery for hundreds of species.
3. Twenty percent of the world’s largest fisheries depend on seagrass.
Seagrasses provide a leafy underwater canopy that creates shelter for invertebrates and juvenile fish. Experts estimate that one-fifth of the world’s most-landed fish species use seagrass as nursery areas, including many commercially important species. Without this crucial habitat, there would be fewer fish to catch and livelihoods could be lost.
4. Seagrasses naturally improve water clarity.
Seagrass leaves slow the flow of water, causing sediment and other suspended particles to settle quickly. Seagrass roots also stabilize ocean sediments. This ecological service improves water clarity and reduces coastal erosion.
5. Seagrass captures and stores carbon.
Through photosynthesis, seagrasses remove carbon dioxide from the water and use the carbon to build their leaves and roots. Plant material that collects on the low-oxygen sediment on the ocean floor decomposes much slower than on land. As this carbon slowly decays it becomes trapped and eventually buried in the soils below. In fact, scientists estimate 10% of the total organic carbon sequestered in the ocean is buried in the soils below seagrass meadows.
6. Seagrasses help protect shorelines.
Seagrass meadows buffer coastal communities from the full impact of waves and protect coastlines from erosion, two services that are becoming more valuable with the increasing frequency and severity of storms.
7. Seagrass is a nature-based solution to climate change.
By sequestering carbon and protecting shorelines, seagrass can help communities mitigate and adapt to climate change.
Healthy seagrass meadows are a nature-based solution to many threats facing coastal waters and communities, including climate change. Governments should protect and restore these key ecosystems as part of their climate change policies.
Stacy Baez manages the scientific portfolio for The Pew Charitable Trusts’ protecting coastal wetlands and coral reefs project.