Climate change - protecting marine life - the value of seagrass

Seagrass - Mediterranean - Shutterstock

 
Over the past decade increasing attention has been paid to the importance and value of ocean marine plants particularly seagrass meadows which flank every continent except Antarctica. Most of the research focus has been directed to the value of seagrass for biodiversity, healthy fish stocks and commensurately, the fishing industry itself.  The critical value of seagrass extends much further and its loss has a range of other impacts worldwide.

Some facts illustrate the critical value of seagrass -

• although it occupies a mere 0.1 % of the ocean floor, the seagrass beds hold around 10% of buried carbon and this marine plant buries carbon up to 35 times faster than tropical rainforests on land.
• this marine plant has evolved into 72 different species with a strong subterranean root system that provides a stabilising effect on coastlines as well as elevating the levels of sediment. This effect is useful for counteracting storm surges and floods by reducing wave energy and reducing water currents.
• with higher rates of carbon dioxide entering the oceans, seagrass has been found to counteract acidic seawater. Carbon dioxide in the ocean creates carbolic acid that dissolves the shells of coral, molluscs and similar organisms.
• meadows of seagrass have been found to create 'Neptune Balls' that are fibrous bundles of plastic items that float in the ocean. Seagrass traps, sorts and sieves microplastics into these bundles each year. Given the sheer scale and magnitude of plastic in the oceans, having a natural method for filtering out this dangerous material is, in fact, a no-brainer solution.

Alas as with so many natural wonders on planet Earth, seagrass itself is under threat and disappearing at a fast rate, around 7% a year by some calculations. 

Ocean Blue and Seagrass Green - carbon sink loss

Seagrass is also a habitat for small fish

When most people think of oxygen production and carbon storage, most of the time trees and forests are the first items that come to mind - but in fact the single greatest source of oxygen on the planet is the ocean. Similarly the ocean is the single greatest resource for carbon capture on the planet mainly through seagrass which is estimated to capture around 27.4 million tonnes of carbon each year. Unlike forests which only hold carbon for approximately 60 years, seagrass is holding carbon stored in the soil below it from the last ice age.

The startling results from research carried out on 946 seagrass meadows worldwide by the University of Western Australia has revealed that these critical resources are disappearing at a rate of 1.5% per annum due to water pollution, dredging for construction and effects of warmer temperatures due to climate change. This means that the carbon stored beneath the plants is being released back into the atmosphere and with an estimated 19.9 billion tonnes of carbon stored beneath seagrass, the scenario of a widespread release of carbon cannot be discounted. If large areas of seagrass die that is likely to be in excess of 299 million tonnes per year.