Seagrass is literally and figuratively the green stuff of the sea, why is no one paying attention? By Joyce Yip; Photos by Thinkstock.
Seagrass is literally and figuratively the green stuff of the sea, why is no one paying attention? By Joyce Yip; Photos by Thinkstock.
IN JUNE 1972, three years after then Virginia Institute of Marine Science graduate student Dr. Robert Orth first settled in Chesapeake Bay for his PhD thesis, Hurricane Agnes spiralled into Eastern US, obliterating what’s left of the region’s seagrass. Though the conditions were dire, this abolition bumped the neglected specie a few notches up conservationists’ and governments’ to-do list “because people suddenly realised how important they were, and they gained an appreciation for the plant” says the researcher.
But decades after the catastrophe, its awareness still slumps behind other coastal habitats despite that one hectare of seagrass is estimated to be worth more than US$19,000 per year, according to the Smithsonian’s Ocean Portal.
Unlike seaweed, whose physiological make-up is much simpler in comparison, seagrass are grass that live in shallow, salty and brackish waters in many parts of the world ranging from the tropics to the Arctic Circle. The first record of seagrass was found around 100 million years ago with 72 species currently on record, some of which weave dense underwater meadows that are large enough to be seen from space. Seagrass are considered the lungs of the sea, whereby one square metre of seagrass generates 10 litres of oxygen every day. They up-cycle nutrients from the soil and release them into the water, slow water flow and capture dirt and silt particles while their elaborate network of roots stabilise the sediment, which not only improves water clarity and quality, but also reduces erosion and buffers coastlines against storms. Though only occupying 0.1% of the seafloor, seagrass are responsible for 11% of the organic carbon in the ocean, which helps reduce greenhouse gases.
This concentration of all-things good makes these underwater lawns prime property for organisms ranging from tiny invertebrates to birds and even algae and micro algae, which attract bigger animals, many of them endangered: it’s also the primary diet for a number of large grazers like manatees, dugongs and green sea turtles. According to the University of Maryland Center for Environmental Science, seagrass meadows attract 10 to 100 times more animals compared to an adjacent sandy bottom.
Aside from its literal sense, seagrass is also, figuratively, the green stuff. According to Florida’s Department of Environmental Protection, the state’s 2.7 million acres of meadows support both commercial harvests of fish and shellfish valued at over US$124 billion. Plus the economic value of their nutrient cycling function along with benefits they bring to recreational fisheries, it reaps in approximately US$20,500 per year.
Yet, man has been slowly killing these precious pastures. Seagrass’ plant-like biological make up of roots, stems and flowers demand photosynthesis and an environment where small changes in temperature, salinity, waves, currents, depth, substrate, day light, pollution, nutrients, epiphytes and diseases can heavily affect them. So though disturbances like animal activity and natural diseases undeniably play a role in damaging the meadows, boat anchors and propellers can kill sections of the seagrass while surface runoff containing fertilisers and other pollutants promote algal bloom that block sunlight necessary for growth and reproduction. Rapid coastal development destroys their peace; rising water temperatures and an increased acidification of seawater as a result of global warming affect their metabolic rate; and overfishing disrupts important components of the food web. According to the Smithsonian, seagrass coverage is lost at a global annual rate of 1.5 per cent, which amounts to two football fields worth of green each hour. In the last century alone, we’ve lost around 29 per cent of seagrass meadows, putting it in the International Union for the Conservation of Nature Red List.
As scientists expect a catastrophic rippling effect to come, the damages are already detrimental for seagrass-dependent species. According to the Frontiers in Ecology and the Environment, there’s on average more than one specie of concern for every seagrassdependent specie across the globe, including ray-finned fish, seahorses and pipefish; and the Smithsonian suggests that before Europeans settled the Americas in the 1400s, the number of green sea turtles supported by seagrass meadows was 15 to 20 times the number and biomass of large hooved animals in the Serengeti Desert alive today.
Yet, despite the catastrophe and their importance, seagrass is not nearly as discussed as corals or plastic management; Orth attributes this lack of attention to its invisibility and less pleasing aesthetics, which, ultimately affect conservation efforts.
“People don’t really see them when they get out of the boat, even if they dip their feet into the water they don’t want to walk on such muddy waters; seagrass is slimy when you step on them, so not really the most beautiful things at sea. When you look at the people who go beyond the coral reefs, they are definitely more interested in corals, mangroves and reefs because you can see them.”
In a paper he wrote in 2006, he alluded that the mentions of seagrass ecosystems in the media are far less than other coastal habitats, citing that salt marshes, mangroves and coral reefs receive three- to 100-fold more media attention than his study subject.
“In addition, although a high diversity and abundance of organisms live in seagrass beds, the animals are often small and cryptic, in contrast to the large and dazzling organisms that attract the general public to coral reefs. The few charismatic megafauna that do inhabit seagrass meadows (manatees, dugongs, and sea turtles) are elusive and not easily viewed in the wild, and because they are endangered by overharvesting and habitat destruction, they are not nearly as abundant as the fish and invertebrates on coral reefs. Without strong public support for seagrasses and the uncharismatic but highly productive animals they shelter, conservation efforts will continue to lag behind those of other key coastal ecosystems,” Orth and his colleagues wrote in the paper.
Though dismal, conservation efforts have already seen drastic improvements since Hurricane Agnes more than four decades ago: after years of trial and error, Orth and his team has successfully seeded 465 acres with 7.65 million seagrass seeds as of 2014. Two years ago, seagrass growth has increased from these plots to cover 6,195 acres.
Likewise, mitigation measures in Mondego Bay, Portugal, reduced nitrogen loads and increased seagrass area from 0.02 km2 in 1997 to 1.6sqkm in 2002 by altering estuarine hydraulics and controlling fishing practices.
On a higher level, actions are being taken to limit damaging practices like excessive trawling and dredging, runoff pollution and harmful fishing practices like dynamite or cyanide fishing, though no international legislation exists for seagrass and protection is still limited to regional and local agencies despite that it’s an international phenomenon. So as cliché as it sounds, it’s a group effort from every global citizen to bring these delicate pastures back to life.
“We watch and observe; we try some things that sometimes bring eye-opening results. Over the last few years, we’ve been focusing much more on the biology, on the requirements for the plants to survive, on how they spread,” says Orth. “If you remove the impediments that are causing the declines, the plants will come back by themselves – that has shown up in our research for years. People are being more and more aware of the environment, and that’s basically what we’re trying to do here: inform people around the world, inform the managers who have the responsibilities on how they implement rules and regulations in the ocean.
