Author: Alix Green

 

Seagrass is one of the most important ecosystems on this planet, vital to the overall health of the ocean. It provides food and shelter for many different underwater creatures. It helps in coastal protection and it’s a big player in the fight against climate change.

However, when it comes to ocean conservation, there a lot of talk about protecting coral reefs or mangroves. However, very little is said about protecting seagrass meadows. Seagrass scientist Alix Green is here to give us a little insight into the wonderful underwater world of seagrass, why it’s so important and how we can protect it.

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What is seagrass? 

Despite common misconceptions, seagrass is the ocean’s only true flowering plant. Commonly mistaken for a type of seaweed, this amazing plant is found throughout the world’s coastlines, only missing from the most polar seas.

There are roughly 72 species of seagrass each with their own unique characteristics. Their leaves span from small 1cm paddles to 5m long blades. Most species are fully submerged although some are intertidal, exposed with low tides. All have complex underground root systems which anchor them to mainly sandy and sheltered shallow coastlines. However, some species can be found up to 30m deep, which is amazing when you consider they rely on photosynthesis to survive.

Yet, despite its abundance, knowledge, science and conservation efforts of seagrass habitats are vastly under-represented. Seagrass lacks the charisma of coral reefs or the imposing presence of mangroves. As a result, seagrass meadows have gone largely unnoticed. As a result, even the most frequented divers and ocean lovers are often unaware of the importance of this habitat.

 

Turtle feeding in a seagrass meadow.

Why love seagrass?

At first glance seagrass may not look like much (in fact, seagrass scientists lovingly term it the ‘ugly duckling’ of the marine world). However, there are a ton of reasons to fall in love with seagrass:

1) A protector of the vulnerable

A huge array of sea creatures make their home in seagrass meadows, from large dugongs, manatees, sharks and turtles to tiny seahorses, pipefish, shrimps and octopus. Look closely and you’ll find a vast collection of commercially important fish and crustacea.

What’s more, these meadows offer the perfect habitat for young fish who use the protection afforded by seagrass leaves to shelter from predators. There is now global recognition that seagrasses are vital habitats for supporting fisheries, both as nursery grounds and feeding grounds, as well as playing a vital role in the lifecycle of those charismatic threatened species which feature on all divers’ bucket lists.

A barracuda stalks prey in a seagrass meadow in Dry Tortugas National Park, Florida.

2) A provider for all

In some developing nations, while the men are out fishing, women and children visit seagrass meadows to carry out a fishing practice called gleaning. They walk onto the meadows collecting sea cucumbers, cuttlefish, octopus and diverse shellfish. This practice is often vital for food security and provides much needed income for women and their families. However, this is rarely recognised by nations as a practice worth monitoring or managing, which makes securing it for future generations challenging. 

3) A fighter against climate change

Much like rainforests, seagrass meadows absorb and store huge amounts of carbon dioxide. Like all plants, seagrasses are photosynthetic and absorb carbon dioxide from their surroundings, converting it into energy with the help of sunlight. They are so productive they can absorb carbon dioxide in excess of their needs. This excess carbon is transported into the roots, which often extend many meters below the surface, where it can then be stored for many thousands of years.

Another way seagrasses can absorb carbon dioxide is via other organisms, from both on land and under the water. Their leaves create dense meadows which slow the water column and force floating particles to settle, where they are then absorbed into the sediment. By trapping carbon in this way seagrasses can remove carbon from the water column that might otherwise be processed through the normal carbon cycle and re-released back into the atmosphere.

Some species of seagrass are up to 35 time more effective at capturing and storing carbon than rainforests, yet no laws are currently in place to promote the protection of seagrass meadows as a way to mitigate climate change.

4) A cleaner of water

As if supporting fisheries and helping slow down climate change isn’t enough, seagrasses also clean the water. Often the closest habitat to land, seagrass meadows filter the water ensuring clean water flows into other adjacent ecosystems, such as coral reefs. 

5) A defender of coastlines

Finally, the deep root structures associated with seagrass meadows stabilise and strengthen sediment and so protect the coastline from erosion. Further, large meadows help slow down the ocean’s waves, which also helps reduce coastal erosion and offers protection to the coastline from storms.

How are seagrasses doing? 

 Unfortunately, seagrasses are faring worse than many of the ocean’s other ecosystems. In fact, they are recognised by the International Union for Conservation of Nature (IUCN) as one of the most rapidly declining ecosystems on earth. A lack of awareness has resulted in poor conservation and management, and often seagrass meadows are lost before we have had a chance to document their presence. Human practices such as coastal development, destructive fishing practices such as trawling, anchoring and mooring damage, poor sewage treatment and pollution all negatively impact seagrass meadows.

The result is the continued global loss and destruction of this important habitat. It’s estimated that 20-25% of seagrass has been lost in the last 50 years and we continue to lose an estimated 7% per year. As these underwater meadows disappear so will the commercially important and endangered species which rely upon them. The result will be a reduction in food security for developing coastal nations, a decline in commercial fisheries, and a reduction in the ocean’s ability to store man-made carbon dioxide.

Above: Propeller damage to seagrass meadow

Right: Dugong enjoying lunch in a seagrass meadow in the Red Sea, Egypt.

What can I do to protect seagrass?

The world can look a pretty helpless place at times and as a marine scientist and ocean lover I would be lying if I said I didn’t have moments where I become overwhelmed by the sate of our oceans. However, the response to BBC1’s Blue Planet 2 (2017) series shows us just what can be done if public emotion is captured. It reminds us that we do have the power to change things, and there is hope in that. Here are seven simple things that you can do to help seagrass meadows today:

      • Sign the Project Seagrass petition: This UK based organisation is doing loads to promote seagrass both in the UK and abroad. They are sponsoring a petition for a ‘World Seagrass Day’ where lovers of this habitat can share their appreciation far and wide.
      • Get up close with seagrass meadows: Next time you’re on holiday why not ask local guides where the best seagrass spots are? Grab a snorkel, or go for a dive, and see what you can find in these amazing meadows. No matter where you live there is almost certainly a seagrass meadow closer that you think.
      • Become a ‘Seagrass Spotter’:  Download Project Seagrass’ android and IOS app that allows you to document the seagrasses you find anywhere in the world. There’s an easy to use set of questions that will help you identify what species you have found and all you need to do is snap a picture and let the app use your location:
      • Are you a teacher? The Community Seagrass Initiative have lesson plans and teaching resources to help you incorporate seagrass into your syllabus.
      • Resources for childrenProject Seagrass have great songs and colouring books to print out.
      • Volunteer and help support seagrass conservation efforts and the wildlife that lives there.
      • Be the voice of change: Share this blog, talk to your friends, write to your MP (or equivalent government official), sign petitions & join campaigns. It’s amazing what sharing your passion can do.

Alix Green

Alix @GreengrassSea is a PhD student at University College London documenting the carbon storage capacity of the UK’s seagrass meadows. She has been a scuba diver for 15 years and during that time has watched the health of the ocean she loves decline rapidly. Until recent years most of her diving and conservation experience has been outside of the UK. Her PhD has brought her closer to the UK’s own unique and beautiful marine environment and she is proud to be able to champion this in her work.