“It’s exciting to discover the hidden magic of seagrasses. If you put a piece of seagrass in a tank in the lab, all the little creatures that inhabit the meadow slowly start emerging – crabs, small mollusks and other invertebrates make the tank come to life.”
The results of new research are as surprising as the hidden worlds seagrass meadows contain; in fact, preservation of these often overlooked ecosystems may prove essential in the global fight against climate change.
Seagrasses are flowering plants that migrated from land into the sea millions of years ago. Seventy-two species of seagrass inhabit shallow coastal waters across the planet’s tropical and temperate regions. Seagrass meadows provide prime nursery habitat for many fish species, as well as an essential food source for grazers like green sea turtles (Chelonia mydas) and manatees (Trichechus sp.).
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Although corals and mangroves receive much more publicity, seagrass meadows are thought to be among the most threatened ecosystems on earth. A recent study by a group of seagrass experts supported by the National Center for Ecological Analysis and Synthesis found that seagrass meadows have been disappearing by about seven percent per year since 1990. Major threats to the ecosystems are caused by several human-induced factors, including destructive fishing, sediment pollution, coastal development and invasive species, many of which will be exacerbated by climate change.
So why should we care about seagrass meadows when so few people recognize them and they appear to have little connection to human well-being?
More than one billion people around the world live within 50 kilometers (less than 32 miles) of a seagrass meadow. People have been using seagrass for hundreds of years for purposes as varied as medicine, packing materials and animal feed. Many communities rely on the shallow waters inhabited by seagrasses for fishing and farming, and seagrass supports fish nurseries for a variety of species important to the commercial fish trade.
Furthermore, seagrasses provide many less obvious benefits important for all coastal communities. Dr. Di Carlo, who is also on the Steering Committee for the World Seagrass Association, emphasizes the connections between seagrasses and the environmental benefits we all rely on for survival. “Seagrass science isn't just about the plant – it’s about how these plants provide the foundation for an entire ecosystem to form.”
They protect coastlines from storms, stabilize sediment and transport nutrients throughout the ecosystem. The global value of this nutrient cycling alone has been estimated at about $1.9 trillion annually. In addition, the health of seagrass meadows is closely tied to that of mangrove and coral reef ecosystems, as many fish migrate between these habitats for food and shelter.
IN DEPTH: Learn more about CI's Marine priority areas.
One of the most important benefits of seagrasses for the world’s oceans is carbon sequestration. In the same way that deforestation is one of the largest contributors to climate change, the loss of seagrass meadows releases large amounts of carbon into the atmosphere. The disappearance of seagrass may even make a more significant contribution to climate change than coral reef destruction, as seagrasses are more widely distributed across the oceans.
Dr. Michelle Waycott, Associate Professor at James Cook University and President of the World Seagrass Association, suggests that the decline of seagrass meadows may be a foregone conclusion unless people recognize their importance.
“For a long time, recognition of the loss of seagrass meadows has been overshadowed by the attention given to coral reefs, marshes and mangroves. We now know that seagrasses play an important role in connecting coastal ecosystems around the world…losing seagrass meadows will only speed up the loss of other ecosystems, causing more problems in the future.”
Expanding Our Knowledge
CI’s Climate Change team is committed to using every opportunity to fight what is arguably the biggest environmental issue of our time. In comparison with other marine habitats, seagrass studies on climate change have been few and far-between; the inter-connected nature of ecosystems makes it evident that more widespread and detailed studies are needed.
The Global Marine Species Assessment (GMSA) aims to fill this information gap. A collaboration between CI and IUCN, the GMSA recently assessed all 72 seagrass species for the risk of extinction under IUCN Red List criteria. Dr. Suzanne Livingstone, Program Officer for the GMSA, explains how the forthcoming outcomes of the assessment will be used.
“The results of this study will identify conservation priorities for CI's Marine Program, highlighting which seagrass species and regions are most in need of conservation action and further research.”
The expansion of seagrass knowledge is an important step in the fight against climate change. By incorporating it into our climate strategy, CI hopes to help provide a more secure future for generations to come.