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Our Blue Planet

What does the future hold for seagrass?

The savannahs of the seas - our humble seagrass meadows - are in peril.

In its Green Seas episode, Blue Planet II introduced us to seagrass meadows. Scarcely touched upon compared to coral reefs, mangroves or even kelp forests, we learnt about the vast potential of these underwater grasslands from their ability to take carbon from our atmosphere to providing habitat for charismatic marine life. But seagrass meadows are much more than this (we would need a whole new landmark series to truly convey how vitally important these habitats are for biodiversity, people and the planet!).

Seagrass meadows are home to charismatic marine life, such as eagle ray’s which utilise seagrass meadows as juveniles in the Caribbean (Credit: Benjamin Jones)
Seagrass meadows are home to charismatic marine life, such as eagle ray’s which utilise seagrass meadows as juveniles in the Caribbean (Credit: Benjamin Jones)

Our understanding of the importance of seagrass meadows is increasing. Recently we’ve discovered how seagrasses filter bacteria from coastal waters, helping to keep both people and coral reefs healthy. We also now know that seagrass meadows are possibly the most under-appreciated fishing habitats on earth, securing food supply and livelihoods. Seagrass meadows are a home, source of food and a feeding ground for numerous species of fish, invertebrates, reptiles, birds and mammals. They protect our shores from erosion, trapping sediment in place and slowing currents and producing oxygen that we breath. They truly are one of the ocean’s heroes. Not the hero our planet deserves, but the hero our planet needs. Our green knight if you will.

Seagrass meadows acan be brimming with marine life (Credit: Benjamin Jones)
Women in Mozambique use fishing nets made from mosquito nets to collect fish within seagrass (Credit: Benjamin Jones)
Women in Mozambique use fishing nets made from mosquito nets to collect fish within seagrass (Credit: Benjamin Jones)

Despite all this, our seagrass meadows are in peril – unacknowledged and never the poster child of ocean conservation.

What this lack of understanding has resulted in is a habitat in a state of emergency. From the shores of the UK to uninhabited islands in the Indian ocean, the tell-tale signs of man’s impact on seagrass meadows is visible. We simply don’t know how much seagrass there is globally. This also means we don’t know how much we’ve lost, best estimates suggest that since the 1980s we’ve lost over 35%. That equates to around a football field every hour [http://www.pnas.org/content/106/30/12377].

A scar on the oceans seabed. A small but visible impact from a boat anchor (Credit: Benjamin Jones)
A scar on the oceans seabed. A small but visible impact from a boat anchor (Credit: Benjamin Jones)

While we are distracted by stories of deforestation and river pollution, the threat we present to seagrass remains largely invisible. Vast plumes of nutrient and sediment rich water flood onto our coastal seagrass meadows every day. Nutrients cause eutrophication, which is an excessive input of nutrients, frequently caused by run-off from the land. Unlike land plants, seagrass meadows are not limited by nutrients, but are limited by light. This means that these massive amounts of nutrients cause opportunistic microscopic algae, called epiphytes, to smother seagrasses, preventing the plants from obtaining food through photosynthesis.

Elevated nutrients cause microscopic algae to smother seagrass leaves, reducing their ability to absorb light. (Credit: Benjamin Jones)
Elevated nutrients cause microscopic algae to smother seagrass leaves, reducing their ability to absorb light. (Credit: Benjamin Jones)

Similarly, sediment from coastal developments and land reclamation bury the sensitive grasses, leaving nothing but a deserted wasteland. Contributing to this is the fact that the fish species that might help seagrasses in their fight are gone; exploited beyond belief and as a result of seagrass meadows being often overlooked when creating Marine Protected Zones.

A static fish fence, or sero, used to funnel fish into a pen so that they can be collected daily has no preference for species or size. (Credit: Benjamin Jones)
A static fish fence, or sero, used to funnel fish into a pen so that they can be collected daily has no preference for species or size. (Credit: Benjamin Jones)

Even in the UK, where we apparently “lead the way” in environmental protection, our seagrass meadows are in a perilous state [http://www.bbc.co.uk/news/science-environment-35199046]. Despite being included within Special Areas of Conservation and Marine Conservation Zones, protection is woefully inadequate.

Despite the apparent doom and gloom there is hope for seagrass. Last year, more than 100 scientists from 28 countries called for global action to protect seagrass meadows [http://wsa.seagrassonline.org/securing-a-future-for-seagrass]. It now seems that people are listening.

It seems there is hope for these vital yet fragile ecosystems. (Credit: Benjamin Jones)
It seems there is hope for these vital yet fragile ecosystems. (Credit: Benjamin Jones)

For our oceans, the future’s bright and the future’s green. Seagrass research and conservation are growing, and new information points to people as part of the answer. Citizen science has the potential to help members of the public to discover seagrass meadows while contributing to conservation at the same time. By making seagrass meadows a familiar species, Project Seagrass (an organisation dedicated to conserving seagrass meadows globally) hopes to use people to leverage change. While some governments are already looking to seagrass meadows as potential blue carbon heroes and actively working on conservation strategies the reality is most are still naively unaware. For change to happen, seagrass meadows can no longer be the ugly duckling of the conservation world and need to be given the limelight they deserve.For our oceans, the future’s bright and the future’s green. Seagrass research and conservation are growing, and new information points to people as part of the answer. Citizen science has the potential to help members of the public to discover seagrass meadows while contributing to conservation at the same time. By making seagrass meadows a familiar species, Project Seagrass (an organisation dedicated to conserving seagrass meadows globally) hopes to use people to leverage change. While some governments are already looking to seagrass meadows as potential blue carbon heroes and actively working on conservation strategies the reality is most are still naively unaware. For change to happen, seagrass meadows can no longer be the ugly duckling of the conservation world and need to be given the limelight they deserve.

Benjamin Jones is a Research Associate at Cardiff University where he works on seagrass meadows and small-scale fisheries. He is a founding director of the marine conservation charity Project Seagrass and works to improve public knowledge and understanding of seagrass meadows. He is especially interested in developing strategies for seagrass conservation which include citizen-science applications and drone technology.

By Benjamin Jones