Seagrasses are a unique group of flowering plants that live completely submerged in the marine environment. Their closest relative on land are the Orchid family of plants, however millions of years ago these unique plants migrated back to the sea and now can spend their whole lives under the sea.
Seeing this habitat in the sheltered shallow coves of South Devon they can be mistaken for seaweed but they are fundamentally different, plants and seagrasses have root structures from which they take the nutrients they require up from the sediments. Seaweeds don’t have a fragile root structure, they have holdfast which they use to hold onto substrates and can grow in many different environments like exposed rocks and reefs, seaweeds which are algae can grow in a variety of places so we find more seaweeds around our coasts.
Seagrasses cover large areas of seabed known as seagrass meadows and these are akin to wild flower meadows, in shallow, sunlit, sheltered waters with sandy sediments. Seagrass meadows grow around the South West coast of England and West coast of Scotland and can grow down to depths around 10 metres below the surface due to availability of light.
In Britain seagrasses habitats are considered to one of the most financially valuable and bio-diverse marine habitats since they provide local communities near by with many different benefits.
These underwater seagrass meadows form complex relationship with their surrounding environment. Fish use these locations as hatcheries and nurseries for young fish, many of which grow to adults and become commercially significant species. A single acre of seagrasses can support unto 40,000 fish.
Shellfish also use seagrass meadows as a place to shelter and grow, the canopy of the meadow is the perfect place for scallop spat to settle since there is a large surface area- and strong currents bringing the food the juvenile scallop needs.
Not only are seagrasses important for commercial important fish but they are home to some of Britains rare marine species like Seahorses.
The two species of seahorse in Britain have poor swimming ability and Seahorses hold on to the leafs of seagrass plants with a prehensile tail so not to get washed away.
Protected under the Wildlife and Countryside Act Seahorses and their habitat are protected. The two species of seahorse we find around Britain are Short-snouted Seahorse (Hippocampus hippocampus) and the Long-snouted Seahorse (Hippocampus guttulatus).
These animals are very rare and if you find one or see one please notify the correct authorities so biologists can understand where these animals are living.
Out of sight out of mind, seagrasses worldwide are reported by the International Union for the Conservation of Nature to be in decline 7% a year making the habitat of the most valuable and fastest declining habitats no one discusses. The loss of the worlds coral reefs regularly makes it to our T.V screens and Corals cover 0.2% of the total seafloor the same footprint to seagrass habitat.
Britain doesn’t have coral reefs but we do have seagrass beds which are calculated to be the 3 most bio-productive marine habitat worldwide.
So by protecting what is on our doorstep we can protect the hand that feeds us through protecting fish nursery grounds and we can have a global influence since seagrasses are one of the planets most effective carbon sinks.
Carbon dioxide from human activity like driving cars, is released into the atmosphere. This then dissolves into our oceans.
Plants and algae use this carbon to grow and form their bodies and the carbon is stored in our oceans, this is called Blue Carbon since carbon is stored in the planets blue spaces.
Seagrasses store this carbon (sequestration) in the sediments and this unique group of plants can sequester carbon 35 times more efficiently than tropical forests. Seagrasses worldwide are being recognised as a significant climate change combatant.
Seagrasses are home to a rich variety of animals included protected species in Britain and animals like Dugongs and Turtles in warmer climates overseas. They provide the communities close to them with multiple benefits for example productive fishing grounds.
They store huge amounts of carbon and quickly so why are these crucial habitats in decline so quickly and why do few people talk about them?
These sites fall out of the publics attention since they are the areas few want to discuss, they are the ugly duckling of marine conservation.
Conservation of the habitat is a complex issue but with the allocation of Marine Conservation Areas around the South West-for example Whitsands Bay, Eddystone Reef, Plymouth Sound and Torbay, these vital habitats are being recognised.
Where these habitats are found in protected areas, efforts are made to halt the decline and try and allow these areas to grow back to good condition returning the lost benefits.
There are efforts to try and grow these plants and replant areas that have been lost. Seagrass beds are like the canary in the cage for coastal waters, if we’re losing seagrass beds around our coasts this indicates our coastal waters aren’t doing too well either.
Water quality: coastal communities should think about what they put down the sink and flush down the toilet.
Unsustainable fishing methods: These tear up the fragile plants and then they find it hard to grow back, you can help by always buying sustainable sourced fish.
Disturbance from boat users visiting the sites and anchoring with poor technique: If you visit these location spare a thought for the impact you may have on the seabed.
The biggest issues facing this habitat are that people are unaware of where these habitats are and how important these special places are to the fish community and the coastal community surrounding them.
Aquatic plants are some of the fastest declining species and habitats on the planet and if we are to protect something so significant we are in a hard place with marine conservation.
We need to understand that our seas have an an influence on us and we have an influence on our seas.
It’s possible for us to all contribute towards stopping the decline of our oceans and seas by adopting an ocean positive lifestyle. If you’re interested in seagrasses or interested to learn you can do to be more ocean positive contact the National Marine Aquarium.