Why is Seagrass Important to Biodiversity Yet Threatened?

The seagrass is highly beneficial to humans and coral health, explains Henrylito D. Tacio, as he interviews Dr. Miguel Fortes, the Philippines' aquatic expert.

Davao, 8 March 2017. No one pays attention to the lowly seagrasses because they are, to quote the word of a friend, “useless.”  There are lots of them along the shores of Pearl Farm Marina and Waterfront Hotel – and even in those coastal areas where population is less.

But with the rampant mangrove denudation and coral reef destruction in the Philippines, seagrasses have become the “last frontier” of the country’s marine needs.

Dr. Miguel Fortes: Seagrass species in the Philippines are threatened, need conservation, preservation and production intensification.

Dr. Miguel Fortes: Seagrass species in the Philippines are threatened, need conservation, preservation and production intensification.

“The whole central portion from low tide to the reef is inhabited by seagrass,” said Dr. Anitra Thorhaug, an American biologist who pioneered efforts in restoring seagrass habitats in the Philippines.  “Yet corals and mangroves have reserved areas, seagrasses none.”

As seagrasses are neglected, they are now fast disappearing from this part of the world.  And it’s not good.  “Seagrass in decline, jeopardizing human, coral health,” said a news dispatch from the Agence France-Presse (AFP).

“Underwater meadows of seagrass offer important protection against pollution to both humans and coral reefs,” said the report which was based on a study published in the journal Science.

“Places with healthy seagrass – where sponges, clams, small fish and other filter feeders thrive – can reduce bacteria that is harmful to both people and marine life by up to 50 percent,” the AFP report said.

Cornell University’s Dr. Joleah Lamb, lead author of the study, was quoted as saying: “The seagrass appears to combat bacteria, and this is the first research to assess whether that coastal ecosystem can alleviate disease associated with marine organisms.”

Globally, seagrass meadows are declining by about seven percent each year since 1990, according to the researchers. 

In the Philippines, the rapid disappearance of seagrass is due to the increasing population’s multiple demands upon the country’s marine environment as source of food, avenues of transportation, receptacles of waste, living space and source of recreation and aesthetics pleasures.

The seagrass ecosystem is likewise adversely affected by mining of industrial minerals; oil spills caused by accidents, operational shipping and refinery activities; dredging and illegal associates.

Dr. Miguel Fortes, one of the country’s foremost experts on seagrass, said these aquatic plants are virtually unknown among Filipinos.  This contributes to the rapid depletion of the seagrass meadows.  

“Huge tracts of these productive habitats are being dredged, filled, polluted, exploited, converted to other coastal uses or simply being destroyed, all in the name of economic development,” deplored Dr. Fortes.

The author of Seagrass: A Resource Unknown in the ASEAN Region noted that most of Southeast Asia’s forests have been reduced by logging and slash-and-burn agriculture, among other factors.  Deforestation and the resulting runoffs cover seagrass beds with silt.

What are seagrasses?

Seagrasses are neither algae nor seaweeds.  Neither are they true grasses.  They are monocotyledonous plants.  Left alone and not disturbed in quiet salty water of coastal zones, they form dense meadows resembling more familiar undulating grasslands in the uplands.

The seagrass is one of the most important components of the coastal ecosystem.  It reproduces through rhizomes and seeds.  It produces seeds annually which are dispersed by tidal currents.

In terms of seagrasses in the world, the Philippines has the second highest number.  Western Australia has more than 30 species of seagrasses while the Philippines has 18 species thriving along its coasts.

Seagrasses in the Philippines cover an area of 27,282 square kilometers. Seagrasses are widely distributed throughout the country – from Bolinao Bay (Pangasinan) in the north, Palawan and the Cebu-Bohol-Siquijor area to the center, and Zamboanga and Davao in the South.

Dr.Miguel Fortes says seagrass is not studied enough although its role in the marine ecosystem is crucial.

Dr.Miguel Fortes says seagrass is not studied enough although its role in the marine ecosystem is crucial.

“Seagrasses are the least studied among the habitats in our coastal zones,” Dr. Fortes deplores. “As such, we know less than we need to in order to use them in solving coastal environmental problems as well as societal problems.”

Unknowingly, seagrasses are a source of salt, soda, warming materials and useful chemicals.  They are used in basket-weaving, mattresses stuffing and beddings.  They substitute for thatch and upholstery material as well as for cotton used in the manufacture of nitro-cellulose.

Seagrasses are also used as fodder for livestock.  They are likewise a major component for sea farming and sea ranching.  The high primary production rates of seagrasses are closely linked to the high production rates of associated fisheries.

Among the diversified species found in the seagrass beds are fishes, sea cucumberssea urchins, crabs, scallops, mussels and snails. Shrimps spend the early stages of their lives in seagrass areas. 

Large animals like sea cow (dugong) and green sea turtles graze extensively in seagrass meadows.  Seahorses, a tourist attraction and of medicinal value, reside in seagrass beds. A study done in five seagrass sites in the country identified a total of 1,384 individuals and 55 species from 25 fish families.

“All these have economic value mostly as food and aquarium specimens,” Dr. Fortes said. “Five times as many fish live in seagrass beds as above sea floors of mud, shells, and sand.”

As stated earlier, seagrass beds are known for being sewage filters.  They are noted for their ability to trap and bind organic and inorganic sediments.  In addition, they are planted along coastal lines to buffer winds, control wave erosions and regain the lost productivity of degraded fishing grounds.

In a position paper presented during the first National Conference on Seagrass Management, Research and Development, Dr. Fortes suggested at least three environmental concepts for better management of the resource: preservation, conservation and production intensification.

Preservation or non-use guarantees the continued survival of seagrass beds or meadows, which may be available for scientific and educational purposes only.

Conservation or wise-use means maximum yield in minimum time.  In time, the seagrass area expands and becomes a renewable resource.

Production intensification can be done through large-scale plantings and so-called “afforestation.”  This transforms biologically desolate and barren impacted subtidal areas into seagrass beds with appropriate techniques.

“As meadows, seagrasses are an important link between land and ocean and support a high primary production,” Dr. Fortes reminded. 

Photos courtesy of Dr. Miguel Fortes.

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