PHILIPPINES SEAGRASS ECOSYSTEM
Seagrass beds - are found in waters and at depths where light can easily penetrate because they require sunlight to photosynthesize. They can be found deeper waters where it is clear but are generally in shallow waters up to three meters in depth. Seagrasses can often be found as an intermediary ecosystem between coral reefs ecosystem and mangrove ecosystem where they play an important role.
SEAGRASS SPECIES: DETRITUS
There are 16 known species of seagrasses in the Philippines, second only to Australia with 17 species out of the 50 total seagrasses found throughout the world.
Seagrass beds are highly productive and most of the organisms that are found in this ecosystem make use of the massive amount of detritus (decomposing materials) for their sustenance. In the Philippines seagrasses are known to support 172 species of fish, 46 species of invertebrates, 51 species of seaweeds, one (1) species of turtle and one (1) species of dugong. Some of the well known and commercially important organisms found here include sea urchins (tuyom), sea cucumbers (bat), and rabbitfish (danggit) to name a few.
BENEFITS & THREATS
Seagrasses are an important refuge and nursery for many economically important fish and other marine organisms as well. Another very important benefit of seagrasses is the fact that they serve as sediment traps and prevent excessive land-based siltation from reaching and smothering coral reefs.
There are many threats to seagrasses in the Philippines and their cover area has greatly decreased over time. One reason for this decrease includes destructive fishing such as trawls and push nets. These gears not only physically destroy and dislodge seagrasses but also catch an excessive number of juvenile fish which are unable to reproduce resulting in a great decrease in populations. Land reclamation and modification of beds due to activities such as dredging also destroy seagrass beds to make way for ports and navigation highways. One of the biggest threats to seagrass beds include siltation from mainland areas due to deforestation which causes turbidity in the water and preventing necessary sunlight to reach seagrasses. Another great threat to seagrasses is pollution which can sometimes cause eutrophication of coastal areas. Eutrophication is caused by the water coming from the land which contains excessive nutrients from fertilizers and sewage. These nutrients catalyze algal blooms which have the potential to kill seagrass beds.
NEED PROTECTIONS
Since seagrasses are so important they should certainly be protected like other coastal ecosystems. It is important to identify and map important seagrass areas so that they can be properly managed. Once this delineation is completed managers can make policies to protect these areas such as establishing sanctuaries and regulations on activities such as fishing, dredging and land reclamation in certain areas.
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