Seagrass meadows are vital marine habitats, providing food and shelter for marine life, improving water quality and helping combat climate change. But how much do you really know about these underwater ecosystems?
Discover 10 fascinating facts about seagrass and why protecting it matters.
1. There Are Around 50 Different Species Spread All Over the Globe
Seagrasses evolved roughly 100 million years ago from plants on land, which is why vast marine meadows can be reminiscent of our terrestrial grasslands. Often confused with seaweed, seagrasses are flowering plants organized into four distinct plant families: Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae.
Seagrasses also reproduce through underwater pollination, using water currents to carry pollen between flowers. They are the only group of flowering plants that complete their entire life cycle in the sea.
2. They LOVE the Sunshine
Seagrasses are found all over the world, on every continent except Antarctica. However, they require lots and lots of sunlight to photosynthesise, so the depths at which they occur in the ocean are limited by light availability.
If you currently find yourself near a bay, lagoon or estuary, we’re willing to bet you’re near some seagrass too.
3. They’re ‘Ecosystem Engineers’, Literally Creating the Foundations of Life
Not only do seagrass meadows produce a staggering amount of oxygen each day, they also bring stability to the ocean floor with their extensive root systems.
This means that seagrasses literally alter the ecosystem around them for the better, creating a welcoming habitat for marine creatures great and small.
4. They Can Store Carbon Up to 35 Times Faster Than Tropical Rainforests
Yes, you read that right, 35 times faster! Seagrass meadows account for more than 10% of the carbon buried in the ocean each year, despite covering only around 0.1% of the ocean floor.
Seagrass is just one promising natural solution to climate change, and one that is undoubtedly close to divers’ hearts.
5. A Single Acre/Hectare Alone Can Support Over a Million Species
Why so close to divers’ hearts? Because of the awe-inspiring, quirky and beautiful marine creatures these habitats support.
Let’s play a quick game: which of the species below does not rely on seagrass?
And the answer is… you guessed it: none of them!
Every single one of these species, and more, relies on the habitats created by seagrass in one way or another.
The sad truth is that when the future of seagrass is uncertain, the future of these beloved marine creatures also comes under threat.
6. They Help Improve Water Clarity
As seawater flows through vast seagrass meadows, sediment and particles suspended in the water column become trapped, too. This means cleaner, clearer water, filtered the natural way.
When the seabed lacks seagrass, sediments can be more easily stirred up by waves and currents, reducing visibility. Without seagrass to help trap sediment, more can also reach delicate coral reef systems.
7. They Provide Crucial Refuge for Numerous Species of Juvenile Reef Fish
Seagrass meadows are often referred to as nursery habitats, as their dense growth slows the flow of seawater, creating shelter for juvenile fish.
Without seagrass or mangroves to hide in, these young marine animals can become more vulnerable to predators in the open ocean or on the reef.
As with all life on Earth, the ability to safely raise the next generation is critical to species survival. When this is threatened, so is the future of marine life.
8. They’re the True Underdog When It Comes to Coastal Community Resilience
You’d be forgiven for thinking that the benefits of seagrass are limited to the ocean alone, but you’d be wrong!
The stabilizing effect of seagrass can help reduce coastal flooding by dissipating wave energy.
In a time of unpredictable extreme weather events, this can mean safer, drier and more resilient communities. These are the same communities where you or your family live, work or spend vacations.
The good news? For every US $1 invested in coastal restoration projects and restoration jobs, US $15 in net economic benefit is created.
9. They’re Under Serious Threat, Disappearing at a Rate of Two Football Fields an Hour!
Seagrass meadows are disappearing at an alarming rate, and an estimated 29% of the world’s seagrass meadows have been lost over the past century. Why?
Natural Threats
- Heavy storms, floods and droughts that make water conditions unfavorable, with human-induced climate change exacerbating some of these impacts
- Damage caused by feeding animals, including sea turtles and manatees, as they search for food
Human Threats
- Removal by resorts that believe their guests prefer a white sandy seabed to a green meadow
- Irresponsible boating practices, including dropping anchors carelessly and sailing in water that’s too shallow
- Agricultural and industrial runoff that degrades water quality
- Destructive fishing practices, such as dredging, which scrapes the seabed and can damage or destroy seagrass meadows
- Reduced sunlight caused by coastal development and infrastructure, including in busy harbors and docks
With seagrass meadows under pressure worldwide, now is the time to act.
If you dive over a seagrass meadow, maintain good buoyancy control and keep your fins and equipment clear of the seabed to avoid damaging these vulnerable habitats.
10. We Are the Solution
As much as we have unknowingly contributed to the destruction of seagrass habitats around the world, we have the power to work together to protect them.
As a global network of Torchbearers, we can save the ocean. There is still hope, and there is still time.
Ready To Do More To Protect the Ocean?
There are plenty of ways to get involved in protecting the ocean. One easy step is to become a Ocean Torchbearer™!
If you’d like to learn more about the threats facing our underwater world and how you can help protect it, explore PADI’s conservation-focused Specialty courses, including the PADI AWARE® Specialty and the AWARE Shark and Ray Conservation Specialty.
