September 15, 2018
The Philippines is tapping its huge carbon stock potential from its ocean’s seagrasses as it has one of world’s longest coastlines that may sequester significant pollutant CO2 from fossil fuel-run vehicles.
The Ecosystems Research and Development Bureau (ERDB) has embarked on a basic research on carbon sequestration potential of seagrass beds.
It was found out that a 50-hectare seagrass meadows in Lian, Batangas can capture 97 megagrams of carbon dioxide (CO2) equivalent to the annual emission of 20 cars.
The blue carbon study likewise involves identification of seagrass species that have high carbon sequestration capacity to offset emissions.
“Some people think seagrasses are mere colonizers and can quickly appear and disappear. Others think that planting of mangroves on seagrass beds is all right. As such, our objective is to unfold another important ecological value of seagrasses in the ecosystem,” said Jose Isidro Michael T. Padin, ERDB supervising science research specialist.
The Philippines was identified by WorldAtlas.com to have sixth largest coastlines in the world with 36,289 kilometers– being an archipelago.
In relation to this, ERDB, as the research arm of the Department of Environment and Natural Resources (DENR), is conducting blue carbon study in other sites—Alabat Island, Quezon; Coron, Palawan; Catanauan, Quezon; and Masinloc, Zambales.
“We’re just waiting for the complete plant tissue carbon content datasets for us to estimate the captured CO2 in other study sites,” Padin said.
ERDB Director Dr. Sofio B. Quintana said ERDB has a thrust to provide DENR the research backup on seagrasses as these have important economic and ecological value. However, such value may sometimes be underestimated due to their indirect nature.
Seagrass experts led by Bryan M. Dewsbury noted these benefits are as direct food source, nursery function (commercial fishes, coral reef fishes and tourism revenue), carbon sequestration, wave energy reduction (erosion control and coastline integrity, coastal real estate value), sediment stability, and improved water quality (from its use of marine nutrients).
Presently, the Philippines does not have any mature technology on seagrass rehabilitation.
Padin said that seagrass transplantation studies have been conducted in the 1990s by academic research institutions in the country, but those undertakings might have gained little success.
“Seagrasses occur in shallow tidal flats, where they are exposed during low tides. Some species can grow down to depths of 12 to 60 meters” he said.
Seagrasses are sometimes found growing together with corals –making up coastal resources that have huge ecological value in preventing coastal erosion, breaking the “power of the waves during storms, tsunamis” (WWF).
In Australia, economic value of seagrass beds has been placed at $103.74 million per year owing to the market price of species as that use these as their home based on productivity model.
“The rhizomes of seagrasses hold the sediment in place and thus reduce the flux of nutrients from the benthos into the water column. This lessens the probability of (potentially pollutant) algal blooms that can cause permanent seagrass loss,” said Dewsbury.
These also have economic value from medical raw materials.
As part of enhancing Philippines’ coastal resources, ERDB is also providing basic knowledge for government on the coral reef status within the Manila Bay Area (MBA).
“People say there are no more corals in MBA, but the recent coastal resource map of NAMRIA tells us that corals can still be found in Naic (Cavite), and Corregidor (Bataan). We just completed validation of corals in Maragondon (Cavite) and Ternate (Cavite),” Padin said.
NAMRIA stands for National Mapping and Resource Information Authority.
The coastal area of Cavite has nearly 290 hectares of coral reefs and ERDB is currently determining the percentage of living corals and population of other organisms in those reefs.
“We’re also trying to determine what to prioritize for protection in areas that can be classified as MPA (Marine Protected Area) so we know where to put the core of the ‘no touch’ zone,” said the ERDB resource person.
The sustainability of seagrasses have been threatened by some human activities such as heavy dredging from construction works, grounding of vessels and motorized boats, release of chemical-filled effluents from human activities, and overfishing.
The fact that 40% of the world’s population live in coastal areas pose threats to seagrass meadows, according to Dewsbury and co-authors in “A Review of Seagrass Economic Valuations: Gaps and Progress in Valuation Approaches.”
The seagrass itself has direct use as raw material for “thatching roofs and making sound proof recording studios” owing to its high silica content, although seagrass capture has been prohibited in some countries due to their value.
Seagrass beds are nursery for juvenile of commercial fishes. They protect small fishes from large predators.
“They are feeding grounds for marine species that inhabit coral reefs in their adult stages…”
Seagrass beds keep sediments through their rhizome structure, reducing siltation.
“The resulting water clarity (from seagrasses) is very important for the seagrasses themselves who are light dependent, but is also important for sometimes adjacent coral reef ecosystems, that depend on high light incidence to survive,” Noted Dewsbury.
“A seagrass die-off in Florida Bay in 1990 resulted in the partial death of coral in the Florida Keys reef tract.”
Their water purifying function cannot be undervalued.
“Seagrass root structure keep water column transparent allowing corals to benefit from high light incidence, necessary for its survival (Rogers, 1990). Seagrasses also house meiofauna that are a food source for some diurnal reef fish species that leave the reef tract to feed in the seagrass beds at night (Robblee and Zieman, 1984).
Seagrass beds also have recreational fisheries value– snorkeling, SCUBA diving, and boating. (Growth Publishing for ERDB)