The importance of seagrasses is further emphasised in a new report that looks at how they underpin fishing worldwide.
These flowering plants, which grow in near-shore waters, are under intense pressure – some estimates suggest global losses are running at 7% a year.
The grasses provide shelter and food for many sea creatures and that makes them a natural draw to fishers.
But Richard Unsworth and colleagues say this valuable resource will need better management if it is to be sustained.
“Our study is really the first to show just how important seagrass meadows are to fishing,” explained the researcher from Swansea University in the UK.
“Wherever you get seagrasses, you get fishing, basically,” he told BBC News.
Seagrass meadows are found around every continent except Antarctica.
The plants cycle nutrients, stabilise sediments, and – as photosynthesisers – act as a “sink” for carbon dioxide.
They also provide nursery habitat for juvenile fish, which hide from predators among the stems.
However, the scale of the importance of the meadows to fisheries has been more supposition than fact because of a paucity of data on how they are actually used, according to Dr Unsworth.
His team set about correcting this by interviewing experts – including other scientists and fisheries managers – on what they were observing around the world.
The team also took in case studies covering all regions from the Philippines to Zanzibar, Indonesia, the Turks and Caicos Islands and locations in the Mediterranean.
The picture that emerges is much the same everywhere.
Fishers actively target seagrasses because they recognise the habitats’ great productivity.
This is true from small-scale recreational activity all the way through to large-scale commercial practice.
The study details the types of tools and equipment used – from spears to nets – and the variety of species taken, from invertebrates such as crabs, shrimp and clams, to popular finfish such as mullet, herring and snapper.
One critical point to emphasise from the assessment is that many hundreds of millions of people worldwide depend on the catch from seagrass meadows for their daily protein intake.
This makes their conservation and proper management all the more important, says the team.
There is a claim that a meadow area equivalent to two football pitches is disappearing every hour.
Such statements are very hard to verify, but there is no doubt that seagrasses are being diminished by poor water quality in coastal areas as a result of agricultural and urban run-off, among several threats that also include insensitive fishing practices.
Team member Lina Nordlund, from Stockholm University, said: “The ecological value of seagrass meadows is irrefutable, yet their loss continues at an accelerating rate.
“Now there is growing evidence globally that many fisheries associated to seagrass are unrecorded, unreported and unmanaged, leading to a tragedy of the seagrass commons.”
Leanne Cullen-Unsworth, from Cardiff University, added: “Arguments in support of seagrass have in the past too often focused on the fluffy – such as the conservation of seahorses.
“I don’t want to dismiss seahorses’ importance, but the reality is that seagrasses have much higher value in supporting fisheries. And I’ve come across numerous occasions where fishermen have been against conservation of seagrasses because they can’t moor their boats in these locations, when it’s those seagrasses that support their activity in the first place.
“What we need to do is increase the level of understanding and appreciation of these habitats.”
The non-profit group’s report found a population drop of 6% in Zimbabwe alone.
Despite their listing under the Endangered Species Act, there is a provision in US law that allows permits to import animal parts if there is sufficient evidence that the fees generated will actually benefit species conservation.
UN climate talks in Bonn have concluded with progress on technical issues, but with bigger questions about cutting carbon unresolved.
Delegates say they are pleased that the rulebook for the Paris climate agreement is finally coming together.
But these technical discussions took place against the backdrop of a larger battle about coal, oil and gas.
It means that next year’s conference in Poland is set for a major showdown on the future of fossil fuels.
This meeting, known as COP23, was tasked with clarifying complex operational issues around the workings of the Paris climate agreement.
One of the most important elements was the development of a process that would help countries to review and ratchet up their commitments to cut carbon.
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Fiji, holding the presidency of this meeting, proposed what’s being called the Talanoa Dialogue.
Over the next year, a series of discussions will take place to help countries look at the promises they have made under the Paris pact.
“A key element in Poland is this Talanoa dialogue, to make sure it doesn’t result in just a talk show,” said Yamide Dagnet with the World Resources Institute.
“In Poland, ministers will have to look each other in the eye and say they will go home and enhance their actions, so that by 2020 we end up with national plans that will be a much more ambitious set of climate actions.”
Looming over these discussions in Bonn was the question of coal, oil and gas.
US coal and nuclear companies organised a presentation here arguing that fossil fuels should be a key part of the solution to rising temperatures.
Glimmers of hope
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Optimistic would be too strong. Slightly less pessimistic would be more accurate. After two decades of grindingly under-ambitious conferences, at last a faint glimmer of light.
The flamboyant flourish of the Paris accord offered more dramatic cause for optimism, with its world leaders, hugs and tears.
But dull Bonn gave a more prosaic hint of what might be achieved if politicians can capitalise on a world shifting towards clean technology far faster than anyone could have expected.
Trump’s snub didn’t derail negotiations, which were mostly cordial, with a clear common goal.
Governments can now see a clean energy future is not just achievable but affordable. Many know they need to cut emissions further, and some are ready to do so.
However, the gulf remains between aspiration and actions. There is acrimony also over the lack of cash to help poor nations.
And the venue of the next annual meeting – Poland’s coal capital Katowice.
So, the battle’s not over, but real-world energy economics are on the cusp of overtaking politics as the main driver of climate protection.
And that’s a glimmer indeed.
Their meeting was interrupted by dozens of singing protestors, who echoed the feelings of many delegates that unabated fossil fuels shouldn’t be part of the future energy mix.
The US seemed to have a divided presence at this gathering.
Leaders from states and cities that want to stay in the Paris agreement were highly visible.
President Trump could “tweet his fingers off, but he won’t stop us,” said Governor Jay Inslee from Washington State.
White House special adviser on climate change, George David Banks, told reporters that President Trump was still open to staying in the Paris pact.
“The President has said multiple times that he is willing to consider re-engaging if he can find or identify terms that are suitable, that are fair to the United States,” he said.
That line didn’t seem to impress many attendees who said there could be no re-negotiation.
Even the US official negotiating team struck a different tone from the White House when they made their national statement to the meeting. There wasn’t a single mention of coal or fossil fuels.
Instead, it stated that the while the US might be out of the Paris deal, it wasn’t walking away from international climate discussions in one form or another.
“The United States intends to remain engaged with our many partners and allies around the world on these issues, here in the UN Framework Convention and everywhere else.”
In a further rebuff to those who came here to promote fossil fuels, the UK, Canada and Mexico, close allies and neighbours of the US, led a new global alliance to move away from coal.
Some 20 countries have signed up to end their reliance on unabated coal as an energy source. The Powering Past Coal Alliance hopes to have 50 members by the time of next year’s meeting in Poland.
2018′s summit in Katowice is seen as a critical junction on the road to making the Paris agreement work effectively when it comes into force in 2020.
By next December, the rulebook needs to be finished and there is to be a key review of carbon-cutting commitments made in 2015.
Many delegates are concerned that Poland’s widespread and continued use of coal makes it unlikely that there will be decisive steps taken at the meeting.
Some observers believe that measures are being taken to ensure that Poland doesn’t derail the momentum that has built up since Paris, and generally maintained here in Bonn.
“We had to leave Bonn with the process intact,” said one seasoned observer.
“We now need a series of ministerial meetings in the coming months to make political progress on the key elements, so that we box in Poland over the next year.”
The Canadian UrtheCast company has formally placed a contract with UK firm SSTL to build its UrtheDaily Earth observation (EO) constellation.
This network of spacecraft, due to launch in 2020, will image the entire global landmass (not including Antarctica) every 24 hours.
One of its key uses will be in “smart agriculture” – taking pictures to help farmers better manage their crops.
SSTL is a world leader in manufacturing satellite constellations.
It has produced series of spacecraft for other EO interests, such as the RapidEye network now owned by Planet and the DMC-3 operation leased to the Chinese concern 21AT.
SSTL is also in the consortium that makes multiple spacecraft for the European Commission’s satellite-navigation system, Galileo.
The Guildford-based manufacturer has been working on the UrtheDaily concept with UrtheCast for a while.
It would see, most probably, eight spacecraft launched into a polar orbit about 600km above the planet.
Arranged like a pearl necklace, these satellites would follow each other, crossing the equator at 10:30 local time.
They would gather something on the order of 140 million square km of land imagery a day (clouds permitting) at a resolution of about 5m.
UrtheCast is a relatively new operator. It started out taking pictures of the Earth from the space station using British-built cameras, and has since acquired the Spanish Deimos satellites to complement its business.
It plans also to launch in the 2020s a novel, high-resolution capability that would see eight pairs of optical and radar satellites circling the globe.
The leading radar satellite would also map the cloud cover so that the trailing optical spacecraft could more efficiently target those regions of the Earth’s surface that were clearly observable.
“We’ve been working with UrtheCast on OptiSAR for about three or four years now, and on UrtheDaily for about the the last year, year and a half,” explained Luis Gomes from SSTL.
“There is an identified need in the market for very high-quality imagery at medium resolution, around 5m, for precision agriculture and environmental monitoring.
“We’d already been developing a design for this kind of system and then UrtheCast said it was the kind of thing they wanted.
“The aim is to have all the satellites built by 2020. That’s a challenge, but it’s achievable,” he told BBC News.
SSTL is about to launch a still and video-imaging satellite for the British EO analytics company Earth-i. The spacecraft, dubbed EiX2, will be the first in what is expected to be a large constellation of platforms.
Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos