Awareness sorely lacking on importance of protecting seagrass
KUALA LUMPUR: “I eat a lot of seagrass and I keep seagrass beds healthy” -- so reads the caption beneath the graphic of a dugong that an international environmental group had posted in its blogsite.
To put it simply, the dugong’s extinction equates to diminishing underwater seagrass communities which, in turn, translates into fewer habitats for all that fish and other seafood human consume.
The humble seagrass is the main source of nourishment for the endangered dugong but there is more to it than meets the eye. Authorities worldwide tend to favour the protection of coral reefs and mangroves over seagrass, little realising the equally important role played by the latter in sustaining marine life.
Seagrasses are actually flowering plants that thrive in relatively shallow and sheltered marine environments with clear waters. Globally, there are 60 known species of seagrasses, occupying only 0.2 percent of the world’s oceans.
Seagrass is often mistaken for seaweed but both are entirely different types of marine plants; seagrass is a plant that produces flowers, seeds and fruits, while seaweed is a type of large algae that only produces spores.
“As far as the survival of the human race is concerned, seagrass beds play a vital role as they serve as a ‘nursery’ for diverse marine species that constitute the (commercially important) seafood resources of any nation,” observed senior lecturer at Universiti Malaya’s (UM) Department of Geography Dr Jillian Ooi Lean Sim.
These marine plants can form dense beds or meadows underwater, which serve as important habitat and breeding grounds for numerous marine species, including fish, prawns, cockles and crabs, that serve as food for millions of people around the world.
According to the Smithsonian Institution’s National Museum of Natural History, each 0.4 hectares of seagrass can support more than 40,000 fish and 50 million small invertebrates.
Ooi said a research team from her department had installed GoPro cameras (that are able to capture full-frame high-definition videos) at various seagrass habitats as part of a study they were conducting, and found them teeming with immature marine species.
“It’s here (seagrass habitat) where they forage for food and develop. But once they become mature, all the species move on to coral reefs,” added Ooi who is also a researcher with UM’s Institute of Ocean and Earth Sciences (IOES).
Seagrass beds are also described as the “lungs of the sea” as they produce copious amounts of oxygen through the process of photosynthesis. According to the Dugong & Seagrass Conservation Project website, seagrasses play an important role in carbon storage, accounting for 10 percent of the annual carbon sink capacity of the oceans.
Two types of seagrass ecosystems were present in Malaysian waters, Ooi said.
One of them is found in shallow waters and the other, in deeper parts of the sea.
“Beting Tenggelam Merambong at the Johor Strait is one of the areas where the shallow water seagrass can be found. Here, when the tide is low, the seagrass bed gets exposed and people can even walk over it,” she said.
The second type of seagrass ecosystem can be found in the waters off Pulau Sibu and Pulau Tinggi in Johor, where the plants remain submerged in water even during low tides.
It is said that the presence of dugongs indicate whether the seagrass ecosystem in an area is healthy or not.
“The dugong’s existence is closely interlinked with seagrass habitat, or vice versa. Dugongs eat mainly seagrass and they are likely to become extinct when there’s no longer any seagrass beds left in our oceans.
“On the other hand, the seagrass ecosystem will deteriorate if dugongs disappear from our seas. Yes, they eat the seagrass but these mammals also play a part to keep these plants flourishing,” said Ooi.
She said due to their feeding pattern, dugongs were known to be “cultivation grazers”. Their intensive grazing on seagrass beds contributes to nutrient cycling and energy flow as they stir up sediment when they uproot whole plants to feed on them.
An adult dugong can consume about 30 kilogrammes of seagrass each day. When seagrass is eaten, it encourages the regeneration of more seagrass. Studies have found that this maintains or increases the level of productivity and nutrition of the vegetation.
When seagrass gets older its nutritional content degrades and, therefore, constant “trimming or pruning” of seagrass by dugongs lead to a healthier seagrass ecosystem. The mammals’ faeces also acts as a fertiliser, which helps seagrasses to re-establish more quickly.
Seagrass ecosystems are increasingly being destroyed, mainly due to unsustainable coastal development; fishing methods like trawling; pollution brought about by domestic sewage and untreated solid waste disposals; and natural disasters like cyclones and climate change.
In Malaysia, the lack of awareness on seagrass ecosystem conservation has led to significant deterioration of this important marine plant’s habitat.
The situation, said Ooi, was causing a lot of anxiety among local conservationists as Malaysia has yet to enact any legislation to protect its remaining seagrass habitats.