The Undercover Hero of the Sea Ellie Wilding explores how seagrass can help to fight climate change
What Is seagrass? Blanketing coastlines across every continent except Antarctica, 72 species of humble seagrass quietly engineer their environment to benefit coastlines, wildlife, and people around the globe. Interest in their existence has been largely unacknowledged until recent years when their abilities to draw in and store huge amounts of carbon from the atmosphere has attracted large scientific attention. Despite their vast global benefits, seagrasses remain poorly understood. Belonging to the same group of plants as grasses, lilies, and palms (monocotyledons), seagrasses have roots, leaves, and veins like their terrestrial counterparts, and function much in the same way. Like any other grass species, they photosynthesise and produce flowers and seeds. Of the 72 species, most live in depths of 1–3 metres where light levels are high, however one species (Halophila decipiens) is known to grow at depths of up to 58 metres. The number of species comprising a meadow varies greatly depending upon location, with the highest diversity recorded in tropical areas where up to 14 species can grow together. What Makes Seagrass a Wonder Plant? For over 10,000 years, seagrasses have been used by humans to fertilise fields, insulate houses, make bandages, thatch roofs, and even weave furniture. Beyond their direct use, seagrass meadows also support commercial fisheries making them one of the most
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The Undercover Hero of the Sea
valuable ecosystems on the planet with one hectare estimated to be worth over US$19,000 per year. 'In Australia, one hectare of seagrass produces 200 kg more fish than a hectare of empty seafloor' says Dr. Maria del Mar Palacios, a marine scientist from the Blue Carbon Lab, Deakin University. Often referred to as ‘lungs of the sea’, seagrasses can generate 10 litres of oxygen per square metre through photosynthesis. They also play important roles in nutrient cycling and water filtration along the coastlines that they occupy. Their roots and blades trap and stabilise sediment, helping to improve water quality and absorb nutrients in runoff from land. The nutrients trapped in the soil by the seagrass can then be taken up and released by the seagrass plants themselves. How Can Seagrass Help in the Fight Against Climate Change? Another feature that makes seagrasses wonder-plants is their ability to mitigate the impacts of climate change. They can do this by dissipating wave energy and protecting coastlines from erosion, but one of their greatest weapons in the fight against climate change is their ability to store and sequester carbon. Dr. Palacios continues 'seagrasses, along with mangroves and tidal marshes, are efficient carbon sinks that are able to draw down atmospheric carbon dioxide back into the ground'. Despite only occupying less than 0.2% of the ocean floor, seagrass meadows account for 10% of all blue carbon stores and can capture carbon from the atmosphere up to 35 times faster than terrestrial forests In fact, Easter 2020
