The Philippines and Vietnam explored the Spratly Archipelago and the Scarborough Shoal by the Philippines-Vietnam Joint Oceanographic & Marine Scientific Research Expedition in the South China Sea (JOMSRE-SCS) in 1996-2007.
The Spratlys are part of the exclusive economic zone (EEZ) of the Philippines.
Four expeditions visited these islands in a span of four years. The Philippine research team for the first two expeditions was composed of scientists from the University of the Philippines-Diliman; the research team for the last two trips were scientists from Silliman University and other universities.
I served as Chief Scientist for the third and fourth expeditions, and helped Ambassador Alberto Encomienda of the Department of Foreign Affairs implement JOMSRE-SCS 3 and 4.
The research program was terminated after the holding of the Conference on the results of the expedition in Ha Long City, Vietnam in 2008. The Proceedings of the Conference was published in March, 2008.
The marine environment of the Spratly island group is unique and is characterized by low islands, shoals, and atolls. The coral reef ecosystem dominates the environment. There are no mangroves. Seagrass meadows and algal beds are sparse. Much of the productivity in the Spratlys is due to phytoplankton.
Monsoons play important roles in surface water circulation which distribute marine propagules, such as larvae of fish and other marine species.
Two gyres (pattern of current) circulating counter-clockwise — the Luzon Gyre off western Luzon and the Nansha Gyre off western Palawan — distribute fish larvae to western Luzon and Palawan during the winter months. These gyres also circulate nutrients from deeper sea bottoms at these times when the deep sea water is less (or not) stratified.
Sampling of fish larvae showed that shallow stations yielded mostly demersal coral reef species, while deep stations were mostly pelagic species of the families Scombridae and Myctophidae.
These two families are likely to reach Philippine waters via ocean currents, like the two gyres mentioned.
It is not surprising that Palawan marine waters are productive of fish, as shown earlier by large catches of muro-ami fishermen in the past.
Muro-ami has been banned since the early 1990s because of the damage it inflicts on coral reefs, which are the habitats of coral reef-associated fish, and its high efficiency in sweeping coral reefs clean of fish.
Pollution and destructive fishing methods are some factors that destroy coral reef and kill adults, juveniles, and larvae of fish.
The South China Sea is a unique marine environment in that it is the area nearest to the Philippines where many atolls exist, two of which were explored by our research teams (North Danger Reef and Jackson Atoll).
In the remote past, atolls were formed from volcanoes, but I do not need to explain their origin at this time. Atolls are generally roundish, oval, or polygonal in shape with emergent islands or shallow reefs that may be exposed at low tides and serve to mark the atoll outlines that enclose deeper lagoons. Sea water moves in and out of lagoons through deeper gaps in the ring-like structure of the system. Lagoons may retain nutrients that are released outside the atolls through water movement.
Our research team found higher concentrations of nutrients in the upper 20 meters of water.
Also, in lagoons were large numbers of juvenile and adult fishes, thus, functioning as centres from which fish and other useful species are held before they disperse to other areas of the ocean via ocean currents, such as the Luzon and Nansha gyres.
But lagoons of atolls could also accumulate undesirable and even dangerous pollutants, such as heavy metal by-products of industries, and sediments, and silt.
Our survey found that the average biomass of target fish in 2005 and 2007 was low, 42.1 metric tons per square kilometre, down from 114 metric tons per square kilometre in 1997, indicating heavy exploitation.
Only four of the eight giant clam species, which are important in providing structure to coral reef systems, were found during our surveys.
The giant among clam (Tridacna gigas) was gone, and so were some important invertebrates, such as sea cucumbers.
One of the recommendations for conserving the environment and biodiversity resources in the Spratlys is for the Philippines and some other countries to create peace parks, a type of a marine protected area. Peace parks function well in at least four areas of the world claimed by two or more nations.
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