Most people have the misconception that Seagrass is like the grass we get in our back gardens, that it can be abused, dug up and cut. However, Seagrass is a lot more sensitive to environmental change. In the last few decades there has been a large decline in seagrass beds worldwide, approximately 50% of Seagrass Beds have been lost, this is not just bad news for the species the seagrass beds support as nursery grounds, but moreover it could be detrimental for mitigating the effects for climate change.
So why should anyone care about some grass in the sea?
If you like eating seafood, whether its Crab, Lobster, Fish or Shellfish and want to keep eating it, you need to do your bit to help protect the Seagrass. The beds provide microclimates for juvenile species, as there are lots of places to hide from predators. Seagrasses as primary producers are food for large numbers of herbivore species, such as Urchins and are also feeding grounds for many migratory species. Secondly, if you live close to the coast Seagrass beds reduce coastal erosion, filter water and trap sediment. It oxygenates the surrounding area for many other species. Seagrass sequest carbon dioxide in the surrounding water and are massive carbon dioxide sinks. So just like chopping down the rain if Seagrass beds are destroyed, not only will there be no further sequestration of carbon dioxide, if the routes of the Seagrass are ripped up it will all release carbon dioxide back into the surrounding water. This will add to the greenhouse gases already in the atmosphere and add to climate change.
Why are Seagrass Beds in decline and what threats do these habitats face?
Sewage, aquaculture and farming all add excess nutrients into the ocean, which leads to algae blooms, in turn restricting sunlight for the Seagrass and reducing oxygen. Coastal development in many areas has physically uprooted and destroyed Seagrass. Dredging for navigation reduces the light levels in the water and can suffocate the seagrass. Anchor damage is another increasing threat with a growing world population flocking to the coasts and increasing recreational boat use.
So what can you do to help?
Never anchor on a Seagrass Bed, find a sand patch. Support conservation bodies and organisations trying to change legislation to reduce water pollution. When driving a boat in shallow water over a Seagrass Bed tilt the engine up and turn it off as to avoid damaging the area. If you live near the coast don’t apply too much fertiliser/nutrient pellets to your garden to reduce the amount of nutrients running into the ocean.
Around the Dingle peninsula we have Seagrass Beds; one of my favourite dive sites just inside of the Dingle harbour mouth is a Seagrass Bed, which supports Thornback Rays, Cuttlefish and many other species!
By Hannah Green
Marine Biologist and Divemaster in training.