In May 2022, the United Nations General Assembly recognized World Seagrass Day to be celebrated annually on 1 March to raise awareness of the critical ecosystem contributions of seagrasses to the marine environment and humanity.
One year on, it is important to emphasize that seagrasses are flowering plants in shallow brackish coastal underwaters worldwide. Although their global distribution is not fully known, they can be identified as seagrass meadows or beds in the shallow seas of the continental shelves worldwide except in Antarctica.
They are essential to humanity, biodiversity and other coastal and marine systems. Their values derive from the complex food webs and microbes they host which in turn serve as life support to keystone and other ecologically important marine species such as seahorses, turtles, seabirds and dugongs. Seagrass meadows are a form of refuge for juvenile shrimps and scallops, providing nursery grounds for about half of all global commercial fisheries.
Through their network of roots, they are able to stabilize sediments and help reduce coastal erosion in the process. They regulate coastal storms as their leaves absorb energy from the waves as they hit the coast. Seagrasses also act as wastewater treatment systems by stabilizing heavy metals and other toxic pollutants while cleansing water of any excess nutrients. They are part of the highly productive “blue carbon” ecosystems – while occupying some 0.1% of the ocean floor, they account for between 10% and 18% of the total oceanic carbon capture. This makes them critical actors for climate change mitigation by sequestering carbon dioxide at rates three times higher than terrestrial forests.
Despite their importance, at least 20% of seagrasses were lost worldwide by the late nineteenth century. These losses accelerated six-fold in the twentieth century due to the ever-increasing intensity of human activities. The drivers of seagrass losses are varied and stem from agricultural, urban development and industrial activities that offload excessive nutrients and sediments into oceans. These inputs foster eutrophication and sedimentation which can undermine the conditions for seagrasses to thrive. Dredging, unregulated fishing, boating activities and rising seawater temperatures are additional contributors to the disruption accounting for most seagrass losses.
At present, in the face of current and future environmental challenges, seagrasses will not survive. One in five seagrass species is classified as either endangered, vulnerable, or near threatened in IUCN’s Red List. As we celebrate World Seagrass Day this year, and in the framework of the Convention on Wetlands mission to halt the loss of wetlands worldwide, we must remind ourselves that it is urgent to protect and restore seagrass meadows for our planet and for posterity.
Failure to prioritize the restoration of wetlands in general, and seagrass meadows in particular, may exacerbate the loss of seagrass habitats and endanger global commercial fisheries. Such consequences may bear far-reaching implications for humanity and other living systems.