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Water Quality and Coral
Reef Health In Boracay, August 1997
Draft August 27 1997
Thomas Goreau SUMMARY Coral reefs and coastal habitats were examined during August 1997 at a range of Philippine sites ranging from high to low human impact. 18 out of 23 locations (78.3%) showed moderate to high levels of algae growth, indicating that they are currently exposed to elevated levels of nutrients. The amount of algae at most sites appeared to primarily reflect sewage runoff from groundwater, but some sites located off uninhabited islands appeared also to be affected by nutrients from episodic upwelling of nutrient-rich deep waters. Because coral reefs will be killed by algae overgrowth fertilized by waste-derived nutrients before bacteria reach levels which are dangerous for human health, coral reef assessment should focus on monitoring and assessing the factors leading to algae proliferation in reef habitats, along with detailed year round monitoring of nutrients in order to identify their source regions, and with a focus on assessing coliform bacteria only in severely polluted areas. Such work should be done by greatly expanding the monitoring capability of DENR and the research capability of Philippine marine research institutions. Protection of the remaining reefs still in good condition will require program s to develop sewage treatment to tertiary level and to use dry composting toilets in non-sewered communities, while ending destructive and non-sustainable fishing practices. Only then will Philippine reefs be able to safeguard the future of the nation’s fisheries, tourism, biodiversity, and shore protection. BACKGROUND Water quality and human health Good coastal zone water quality is central to the health of both bathers and of coral reefs. Sewage enters coastal waters when it is released directly into the sea, is carried via rivers and gullies, or drains into groundwater from septic tanks and pit latrines which then flows into the sea through sand and limestone. Sewage effluents carry bacteria and pathogenic organisms which can cause illness or even death, depending on their concentration and virulence. Most sewage microorganisms are killed in the sea by the action of salt, high temperatures, and high light, but the rate of their destruction is greatly slowed if waters are turbid with suspended sediments. The major human health problems which are known to be caused by micro-organisms in sewage contaminated coastal waters include gastrointestinal illness (stomach pains and diarrhea), ear infections, shellfish poisoning, and cholera. Because of the wide variety of medical problems which can be transmitted by coastal waters and the lack of funds to develop and apply specific assays to monitor all of them, a single assay, for coliform bacteria, is generally used as a simple assessment of overall sewage contamination levels.
Coliform bacteria as an index of pollution The reason for the coliform assay is that one species of coliform bacteria (Escherichia coli, or E coli for short) grows in the human gut, and makes up around 70% of the bulk of human feces. The latest and best introduction to its importance is in a recently published publication by Blattner et al. (1997, Science 277: 1453-1474) of the first complete genome sequence of this bacteria, a study which will result in important new information on how different varieties act. They state: “E coli is an important component of the biosphere. It colonizes the lower gut of animals and as a facultative anaerobe (capable of living both with and without oxygen) survives when released to the natural environment, allowing widespread dissemination to new hosts. Pathogenic E coli strains are responsible for infection of the enteric (stomach and gut), urinary (bladder and kidney), pulmonary (lungs and throat), and nervous system (nerves and brain).” Therefore measurements of coliform levels are a good measure of the presence of sewage contamination. However there are several important complications. First, there are many types of coliform bacteria. The name simply refers to bacteria with a round shape. Coliform bacteria include those derived from feces as well as unrelated strains. Fecal coliform bacteria include different species which grow in the guts of many different animals, including cattle, water buffalo, horses, pigs, and turtles, as well as humans. While in most coastal zones human bacteria are likely to predominate, tests to separate human fecal coliforms from other fecal coliforms tend to be too expensive and impractical to use in regular monitoring, so total coliforms and fecal coliforms are usually measured. A second complication is that there are thousands of different strains of human coliforms. While many of these are fairly benign to those who have become exposed to them, exposure of persons from remote areas, such as tourists, to benign local strains to which they are not accustomed causes them to develop diarrhea or stomach cramps as the new strain competes with their native stomach bacterial populations (as happened to one member of our team, forcing him to cut short his work). Other strains may cause bleeding or prolonged illness, and a few very rare but increasing strains can cause fatalities. Identifying these many strains with different medical effects would take regular analysis of the DNA of coliforms in water, an assay which has not yet been developed to be applied in a cost effective manner for routine monitoring. A third complication with standard assays for coliform bacteria is that the most dangerous microorganisms causing toxic or contagious diseases are not measured. A fourth complication is that coliform bacteria prefer to live on suspended particles than floating free in the water. Measurements of coliform bacteria are therefore notoriously variable since the amount measured depends on the amount of particles which happen to be in the water sample, which varies enormously over short distances and time intervals even under uniform conditions. A fifth complication is that the values measured are extremely sensitive to the direction and intensity of waves, currents, tides, and to rainfall. Typical values will fluctuate enormously at any site, often reaching very high peaks in the middle of periods of otherwise moderate or even very low values. Because of all these complications vast amounts of measurements must be made to get an accurate estimate of the medical risks posed by sewage contamination, and most professionals regard the actual numbers as only a very crude estimate of overall pollution levels. This is often not appreciated by non-specialists, and is part of the reason for the misunderstandings over ongoing measurements which has resulted in the unfortunate controversy at Boracay which led to loss of tourism revenues and to this study at the invitation of the Secretary of Tourism, the Honorable Mina Gabor. It should therefore be made clear at the outset that the high population and inadequate sewage treatment at Boracay certainly results in contamination of the coastal zone which will be generally fairly low when the number of people staying on the island is low, the rainfall is low, and the winds blow onto the beach, and generally higher when the opposite conditions prevail. The level of development of Boracay is sufficiently high that coliforms should be episodically high, but low or intermediate values should often be found, and the levels should be much lower than that found in the harbors and nearby bays around any Philippine coastal port city. However long before water quality becomes inadequate for human health, it becomes inadequate for coral reef health.
Philippine coral reef health The Philippines lie in the world’s most biologically diverse area of coral reefs, and these reefs are crucial for the nation’s fisheries and shore protection, as well as the source of white beach sand for the expanding tourism industry, a major source of foreign exchange earnings. While some Philippine reefs are regarded among the finest in the world, the majority have been severely stressed by destructive fishing practices, such as use of cyanide and dynamite, which kill corals on a large scale, or from greatly accelerated soil erosion and coastal sedimentation resulting from deforestation, according to studies by Edgardo Gomez and Helen Yap at the University of the Philippines Marine Science Institute (UPMSI). A recent summary of the condition of 775 Philippine coral reefs (Yap, 1997) found 5.0% in excellent condition, 26.2% in good condition, 39.4% in fair condition, and 29.4% in poor condition. While the Philippines has long had a notorious reputation among conservationists for uncontrolled and unsustainable harvesting methods used for locally consumed food fish, export food fish, aquarium fish, corals, and shells, the Philippines has made a dramatic change in enforcing the CITES Convention with regard to coral and shell exports and in being the first and so far the only country in the world to thoroughly monitor all aquarium fish exports for cyanide. By cleaning up its act the Philippines should greatly improve its international reputation and attract investment in tourism and in sustainable natural resource use. But there is much more that needs to be done before the corals and the coral reef resource can recover.
Water quality and reef health in the Philippines Until recent studies in Manila Bay by Gil Jacinto (UPMSI), Puerto Galera by Mary Lou San Diego-McGlone and Porfirio Alino (UPMSI), and Boracay by Pierre Pillout (Newcastle), relatively little work was done on coral reef water quality issues in the Philippines. The Philippines has a population density of around 220 persons per square kilometer, a level almost identical to that of Jamaica, an island where the reefs have been almost entirely killed by algae overgrowth of corals because the waters have been over fertilized with the nutrients nitrogen and phosphorous from land-based sources, mainly sewage (Goreau & Goreau, in press). This process, called eutrophication, is certainly affecting all reefs near population centers and resort areas in the Philippines unless local populations are very low, waves and currents are very high, or sewage is treated to a level which ensures that the nutrients are absorbed on land without reaching the coastal zone. It must be emphasized that sewage which has been treated to a level that it meets all drinking water quality standards may be colorless, odorless, tasteless, and free of dangerous microorganisms, but that it is still grossly polluted from the standpoint of coral reefs, as humans can drink water with nutrient concentrations up to a hundred times higher than that which causes reefs to be killed by algae overgrowth. Depending on the amount of nutrients and the amount of grazing by fish and sea urchins, a wide variety of algae can proliferate, ranging from low turfs to dense mats of vegetation which smother and kill corals. Recent work shows that nutrients are the major control on algae abundances, and reducing nutrients is the only step effective in cleaning up reefs. Certain species of algae have been identified as indicator species for high nitrogen or for phosphorus. In particular, proliferation of slimy mats composed of cyanobacteria (also called blue green algae, although they come in several different colors), are often an indicator of high sewage inputs or of unusually elevated phosphorus to nitrogen ratios. In many places in the Pacific, Indian Ocean, and the Caribbean we have been able to identify sites where sewage is soaking into the sea from the distribution of cyanobacterial mats. Algae abundance and types are a far more sensitive and visible measure of the health of the reef with regard to sewage contamination than the concentration of coliform bacteria, and allows the early signs of deterioration to be identified and corrective measures applied to avert contamination before reefs die and people get sick.
Background to the present report This study was conducted at the invitation of the Ministry of Tourism, and was initially focused on the coliform levels near the beaches at Boracay. The Global Coral Reef Alliance team felt that the variability in coliform counts could lead to uncertain conclusions based on the few samples which could be taken in the short time available, and requested to expand the study to encompass the broader range of water quality issues affecting the reef habitat and to contrast the situation at Boracay with other sites spanning a broad range of conditions as this was essential to providing the best possible advice to the Ministry on the environmental sustainability of tourism development at Boracay and other sites around the Philippines. In addition the original controversy over conditions at Boracay resulted in the establishment of a detailed and greatly expanded water quality study being conducted by DENR. We felt that there was little need to duplicate the solid monitoring program already underway, and that it would be most useful to DOT, DENR, and Philippine research and conservation institutions to conduct sampling and observations which would complement and add to these ongoing studies. We therefore arranged to take water samples for nutrient analysis at some of the sites analyzed at Boracay for independent analysis by the marine chemistry laboratory at the University of the Philippines Marine Science Institute, and to take additional samples both further away and closer to the shore. This will serve both to cross calibrate and confirm the accuracy of the data, and to add information on likely nutrient source areas. It is our experience that water quality laboratories which focus on pollution of drinking water, rivers, and sewage plants normally use analytical methods which are not sensitive enough to obtain accurate nutrient measurements in seawater, and that it is necessary to perform analyses in a laboratory dedicated to using the more sensitive analytical methods used for seawater analysis. It is an indication of the serious attitude of the Ministry of Tourism towards obtaining the best possible advice for sustainable management of tourism and the Philippine marine environment that they readily agreed to this expansion of the work program carried out by the Global Coral Reef Alliance Team.
OBSERVATIONS Introduction and overview This section is arranged by reef sites examined at each of the four locations, Boracay, Isla Verde, El Nido, and Balicasag, in the order in which they were examined. At each location the overall sewage situation is described, assessed, and site specific recommendations are made. Overall recommendations are made in a later section. Observations and 15 hours of digital video films were taken at 23 reef sites. The video serves as a permanent record of reef conditions at the time of sampling which can be used for quantitative studies and to provide a baseline to assess future changes. There has not been time to review all of these films in detail in this first draft report. It is intended to use images from the films in the final version of the report to provide information on the conditions of the reef with regard to live coral cover, algae cover, fish abundance, coral bleaching, coral diseases, and water clarity, but this work will take a great deal of time and we do not yet have all of the hardware and software needed for digital editing of the films and for quantitative image analysis. We note that there is a great deal of material which we hope to edit to provide short documentary footage suitable for public education, tourism promotion, fisheries management, and conservation planning, as well as for scientific data analysis and environmental records. In this draft report we focus on rapid assessment of coral reef health and on visible signs of eutrophication in the marine bottom habitat, on the sea surface, at the shore line, and on the adjacent land. Results of the water quality analyses will be added to the final version when these become available. Due to the short time period available to complete the first draft prior to leaving for several months field work in the Indian Ocean and South Pacific, it was thought best not to delay the preliminary draft report which can still serve a useful function in rapidly delivered draft form which can be immediately useful even though incomplete. However we must caution that the final version will be considerably expanded qualitatively and quantitatively once additional data and comments can be incorporated into this first draft.
A) BORACAY The first eight sites mark the eight locations which were concurrently monitored by DENR. We went out with them on their routine sampling, and made observations at the same sites. Following the controversy over water quality at Boracay, DENR initiated biweekly measurements at 15 sites, to continue for a year. Due to weather considerations, the sites on the rougher western side had been omitted in previous samplings, so the focus was on that side even though the seas was rough. Due to lack of time only 8 of the 15 sites could be monitored. 5 sites were examined on the west side of the island, spanning its whole length, and one site each on the north, south, and east sides. We observed that while measurements were made of the temperature, salinity, pH, oxygen, and turbidity of the water, and water samples were collected for analysis of coliform bacteria, nutrients, and biochemical oxygen demand (BOD) by the DENR / DOH / DST team, no ecological assessment was included in the monitoring program . We therefore felt that the most useful addition to their program would be to film and rapidly assess the condition of the bottom marine ecosystems at each site. In addition, because this sampling was conducted in waters around 5 to 10 metres deep in a belt around 100 metres offshore we supplemented this with water sampling and ecological observations in areas both offshore and inshore from this transect. The following notes contain a brief summary of reef or marine ecosystem health at each site. The numbering used here is not the same as that used by DENR. Our site 1, on the southeast, corresponds to DENR site 6, site 2, located off the southwest of the island corresponds to DENR site 9, sites 3, 4, 5, 6, and 7 are taken along a south to north transect along the west coast parallel to the main beach and tourism area and correspond to DENR sites 10, 11, 12, 13, and 15 respectively, while site 8, located off the north of the island corresponds to DENR site 1. All sites are indicated on map 2.
1) This site had very low live coral cover, between 1 and 5%, and is over 90% covered with dead coral rubble. This rubble could have been caused by either old dynamite fishing or by typhoon waves, but the fact that corals are lying randomly in all directions rather than lined up in a predominant direction suggests that dynamite was responsible. The amount of rubble corresponds to what must have once been a large reef dominated by branching corals, and there has been very little recovery since its destruction. The bottom organisms are dominated by large amounts of a branching sponge, which indicates that high levels of bacteria, the food of sponges, are present in the water. The rubble is largely covered with fuzzy brown and green algae growth made up of fine filamentous algae and cyanobacteria (also known as blue-green algae) on which young corals cannot settle and grow. Sand patches between the rubble fields are also covered with cyanobacteria mats. Large numbers of algae eating black long spined sea urchins (Diadema setosum) are present, but appear not to be able to control the algae overgrowth of the hard bottom. Towards the shore there is a sand belt which is largely covered with slimy brown patches of cyanobacterial mats, which appear to be growing on nutrients which are percolating from land through the sandy beach. The water was turbid.
2) This site, located off a rocky unpopulated shore near to the well flushed channel between Boracay and Panay, was in the best condition of any near shore site seen. Live reef building corals covered around 70% of the bottom, and species diversity was high and dominated by fragile and healthy branching and plate corals. There was no rubble between the coral heads, only clean sand. This strongly suggests that typhoon damage did not cause the deterioration of inshore reefs on Boracay, and that dynamite is likely to have been the cause of destruction seen at other sites. The water was blue and far clearer than at any other near shore site seen. Large algae, turf algae, and cyanobacteria were very rare or altogether absent.
3) This site was dominated by broken dead branching coral rubble and small dead coral heads, with sand in between. Live corals were small and covered about 20% of hard bottom. Fuzzy algae turf and red and brown cyanobacterial mats covered a large portion of the dead corals. Although the water was turbid, this site had either been less severely damaged than the first site, or had managed to recover slightly.
4) This site was dominated by sand, which was clean, white, and ripple marked, indicating that it was not stabilized by surface cyanobacterial mats as at other sites. Patches of hard bottom had low live coral cover, and were dominated by soft corals or dead corals and rubble covered with fuzzy cyanobacteria. The water was turbid.
5) This site was dominated by sand and seagrass beds. The water was turbid and there were almost no live corals, except for a handful of small colonies. The sand was covered with patchy mats of cyanobacteria. The seagrass was distinctly eutrophic in appearance, containing large amounts of the algae Hypnea musciformis, Dictyota sp., and Galaxaura oblongata, overgrown with Chaetomorpha linum and cyanobacteria.
6) This site was dominated by sand, with some seagrass. The seagrass had large clumps of the eutrophic alga Hypnea musciformis, but overall the level of algae in both seagrass and sand were less than at the previous site. The water was turbid. There was a single very large coral mound, covered with small to medium sized corals up to a metre across, and with cyanobacterial turf on dead coral surfaces.
7) This site was dominated by sand with small coral heads. Coral heads covered about 30 percent of the hard bottom, and colonies were small. The water was turbid. The bottom appeared very fuzzy due to dense mats of brown cyanobacteria on sand and dead coral rubble. Large green algae turfs, probably Anadyomene or Microdictyon sp., were found on rubble and dead corals.
8) This site was dominated by branching coral rubble, with only small amounts of interstitial sand. The rubble appeared to have been caused by dynamite. No live corals were seen. Fuzzy filamentous algae turf, overgrown by cyanobacteria, covered the dead coral rubble. Small clumps of the weedy alga Acanthophora spicifera were present, along with larger patches of the beneficial sand-producing green alga Halimeda sp.
9) Inshore sandy areas along the beach running along the western shore of the island were covered by cyanobacterial mats. Seagrass areas were distinctly eutrophic with weedy algae, especially the fuzzy green filamentous alga Chaetomorpha linum. This species is a major indicator of high levels of nutrients, in particular phosphorus, which is usually derived from sewage and from detergents. Chaetomorpha was present in small clumps around the bases of the seagrass. This species is especially dangerous because when the water is calm and nutrients build up it is capable of forming long green strands similar in appearance to cotton wool, which are broken off by waves and can be wrapped completely around corals and smother them. It is also certainly the green algae which locals describe as competely covering the inshore sandy areas from January to March, and which forms thick floating mats which wash ashore and must be raked off daily. Although some locals feel that this algae turns into sand this is completely incorrect. Those calcareous algae which turn white and turn into sand when they die, like Halimeda and Galaxaura, do not float, and they are being overgrown by non sand producing weedy species. Chaetomorpha does turn white when it dies, but this is because the green chlorophyll is rapidly destroyed, and the resulting material rots before it can dry, and ultimately decomposes completely. This species is a favorite food of surgeonfish. Local sources indicate that this algae used to bloom briefly in front of the beach at the calmest times, but that the extent and duration of the bloom have steadily increased over the last 10 years and become a season long problem which negatively affects the water bathing quality, as swimmers can not see the sand bottom, and must step on and be wrapped up in large green streamers. This alge species has been a major coral reef killer in other parts of the world. The only effective control known is to cut off its supply of nutrients from land. One bay in Jamaica where the beach and seagrasses, along with the reef, were being overgrown by Chaetomorpha linum and other weedy algae was successfully cleaned up last year by diverting all sewage and detergent from disposal in the sea, and applying it instead to water and fertilize lawns and ornamental vegetation. The weedy algae had visibly decreased within weeks, and were almost completely gone within two months (Goreau et al, in press). This indicates that nutrient reduction can be extremely rapid and effective if it is sufficiently large in magnitude. The same strategy is likely to be the only one which can work in Boracay, as the algae grows so fast when nutrients are high that it is virtually impossible to remove it. In addition to Chaetomorpha, large amounts of other weedy algae were washed up on the beach, including Hypnea musciformis, Acanthophora spicifera, Dilophus alternans, Gracilaria sp., and a calcareous branching red alga resembling Haptolithon or Corallina. To determine if groundwater seepage is enriching nutrients in the nearshore zone, water samples were collected off the beach in waters one metre deep, and groundwater samples were obtained from a local well.
10) Santos Place, offshore northwest Boracay. Surface water sample collected. The reef at this site was located on a smoothly sloping bottom, and was composed of around equal amounts of soft corals and hard corals. Visibility was good, a bit less than 20 metres. The site is subjected to episodic high wave energies, which appear to favor soft coral growth and rounded massive hard corals. The corals were in good health, and there were no large algae or cyanobacterial mats. Sand between coral mounds was clean and free of cyanobacteria. Dead coral surfaces were overgrown with encrusting calcareous red algae crusts, which produce a limestone cement, and are typical of low nutrient conditions. However these were affected to some degree by the recently discovered Coralline Lethal Disease (Goreau, et al, in press). This disease, of unknown origin, kills pink coralline algae crusts. A spreading white rim marks the boundary between pink algae and dead areas overgrown with a green filamentous alga. The disease, which has also been found all across the Caribbean and in the southwest Indian Ocean, appeared to be moderately advanced compared to those other areas.
11) Angol, offshore southwest Boracay. Surface water sample collected. The reefs at this site, although rarely dived on, are regarded by local dive masters as typical of the offshore reefs of western Boracay. The reef was in excellent condition. The visibility was good, over 20 metres. Live coral covered over 90% of the bottom, with very high species diversity, large healthy corals, and good vertical growth. No weedy algae or cyanobacteria were seen. There was little dead coral, and this was covered with the encrusting calcareous red algae, Porolithon, which was somewhat affected by CLD. Diseases were also seen on several coral species, including white band disease on branching Acropora and an unidentified line disease on Porites. The excellent condition of this reef indicates that the source of nutrients must be from the island and not from water masses being pushed onto the island by the southwest monsoon, and that the negative impacts seen in inshore areas have not yet reached the area, even when the wind pattern reverses. This area, around a kilometer from shore, provides prime diving which has not yet been negatively impacted. If nutrient sources from the island can be cleaned up, the reef has excellent prospects for being sustained in prime condition. Moorings should be installed at all dive sites to avoid anchor damage, and tourists rigorously trained to maintain their buoyancy and not touch the corals.
12) Laguna de Boracay, offshore east Boracay. Surface water sample collected. Visibility was poor, less than 10 metres, and the water was green and full of suspended organic matter. There were large amounts of soft coral, and hard coral diversity was lower than on the other side of the island. The reefs had large amounts of algae, including thick gooey cyanobacterial mats overgrowing dead and living corals, filamentous algae turfs, and large clumps of the sand producing algae Halimeda and Galaxaura. This algae abundance was somewhat surprising given that this side of the island was calm and protected, and indicates that nutrient inputs must be considerable. Little diving takes place on this side because reefs are not in as good condition. The clear evidence of eutrophication suggests that a major source of nutrients may lie in discharges of sewage contaminated groundwater from local populations in the interior villages. Although there is still little tourism development on this side of the island, the majority of local residents live in the villages in the interior, and the major natural drainage of wetlands and seasonal streams is towards this side. Any further sewage drainage into this area, whether from increased local populations, new tourism developments on the north and east, the large golf course being constructed, or sewage discharge will cause the reefs to deteriorate further unless strict measures are taken to absorb the nutrients before they can reach the sea.
Sewage treatment Boracay has a beautiful beach which unfortunately shows classic signs of the impacts of uncontrolled and excessive development in advance of developing sewage treatment infrastructure needed to protect its natural beauty. While existing data indicates that water quality is generally adequate for bathing, it is episodically unsuitable, especially at the peak of the tourist season when the beach is calm, and rainfall is low. The ecological observations show significant impacts on nearshore and eastern reefs, but western reefs are still in good shape. Protection of the good reefs and restoration of damaged areas will take time once water quality is improved, but that nutrients will need to be reduced to below coral reef eutrophication levels first. At present the island has little or no suitable sewage treatment for a coral reef area. Most of the resident population of around 10,000 people disposes of their sewage directly into pits in the ground or into surface drainage, which soaks directly through the porous sand and limestone into the sea. While some hotels have septic tanks this is not sufficient to solve the problem. First, there are no facilities to pump out the tanks, so they fill up and the excess flows into the groundwater. Secondly, building extra chambers is not a solution, as the bulk of the nutrients generated by decomposition of wastes go into solution and are not removed in the tanks and are discharged into the ground in the overflow. DOT, recognizing the importance of maintaining water quality in Boracay for the viability of the tourism industry, has obtained funding from the Government of Japan’s Overseas Development Assistance Program for building a safe water supply for residents (who now use polluted groundwater wells) and a sewage collection and treatment system. Construction is due to start next year. We met with the sewage design team, and found them to highly knowledgeable and competent. Unfortunately though, the plans now being used are inadequate to reduce nutrients to safe levels for the reef. This is not the fault of the design team, who are fully aware of the problems, but due to inadequate funds for a complete system which treats the sewage to a level which allows the waste effluents to be reused on land and the nutrients to be absorbed by land vegetation (biological tertiary treatment) and prevented from reaching the sea where they over fertilize the reefs and seagrasses. The sewage design team were aware or the need for further treatment, and wished to see the effluents re-used to fertilize land plants in either managed or natural wetlands or on the golf course. Due to their terms of reference they are unable to recommend application to watering the golf course greens, even though this would both absorb nutrients which must be prevented from entering the sea, while at the same time avoiding the need for importing expensive chemical fertilizers which are likely to leach into the nearshore zone through the limestone. Due to lack of funding and inadequate areas of natural wetlands, the designers were instead forced to compromise with an ocean outfall design. The consequence of the present design is that while this system will greatly improve the bacterial water quality on the beach side, it will have the effect of concentrating all the island’s nutrients on the already impacted eastern reefs, and accentuate ecological stress on that side especially during the calm season. In our view additional funds should be sought to solve the environmental health problems by adding a tertiary treatment phase to the current sewage plans, so that effluents are not discharged into the sea but instead used to fertilize wetlands, golf course greens, and ornamental vegetation. Almost all the natural forest on Boracay except on some rocky and uninhabited areas in the north have been cleared, and much has been lost to the golf course and related hotel development. What is left of the vegetation is largely a low value secondary scrub or imported tree species. In our view the Government should require the golf course to use secondarily treated effluent for watering the greens, thereby freeing up the water which would otherwise have to be imported from Panay for this purpose, denying their use to local residents. A further step could be taken to establish an ecological restoration zone for forest restoration in the interior of the island in which the natural vegetation would be fertilized and encouraged to grow back. This area should be a wildlife refuge. After suitable recovery, the watering could be switched to other restoration zones, and the area opened up for nature walks, hikes, and wildlife watching, which would greatly add to the island’s tourism attractions, while providing it with a reputation as a pioneer in environmental protection and improvement.
B) ISLA VERDE 13) Northeast. This site had fairly good coral cover, around 70% dominated by low thickets composed of small colonies of Seriatopora hystrix, a coral which is well adapted to muddy water. The water was very turbid, with visibility around 6 to 8 metres, Considerable areas of dead coral were densely covered with cyanobacterial mats. Dead table corals had been killed by cyanide poisoning, according to local fishermen. They were almost completely covered with cyanobacteria of greenish-brown, red, and lavender colors, and showed very little settlement and growth of young corals.
14) North. This site was far more dominated by branching and table-like Acropora species than by Seriatopora, and had once been a spectacular reef. However it was being heavily attacked by a huge swarm of the coral eating and poisonous Crown of Thorns Starfish, Acanthaster planci. At least a hundred of these were seen at this site, and they had killed around a third of all the coral. Dead coral was overgrown with thick mats of cyanobacteria of at least four different types. The venomous starfish occurred in a range of sizes, indicating that they were successfully building up their populations. This reef will be severely damaged by Crown of Thorns unless prompt steps are taken by the local fishermen to remove them. Coral recovery will be very poor because of the great extent of cyanobacterial cover on dead coral, which prevents new settlement of juveniles. Despite heavy fishing by aquarium fish collectors, these reefs still have an good variety and numbers of fish. Most fishermen now use nets rather than poison, to prevent damage to corals and fish. However in diving with hookahs to set their nets, fishermen are often stepping on and breaking the fragile branching corals.
Sewage treatment Coral reefs around Isla Verde are reported by many divers to be in considerably better shape than those around Batangas, yet it is clear that they are being subjected to excessive levels of nutrients which are causing failure to recover. The eutrophication around Isla Verde appears to be due to two sources. Local sources come from the resident population of the island, fishermen who use pit latrines. To clean up local sources of nutrients they need to obtain information on constructing dry or composting toilets, which following suitable decomposition will provide a safe organic fertilizer which is badly needed on this infertile and rocky limestone island. A program is needed to provide funds for purchasing the needed construction materials if villagers are willing to contribute the labor. Isla Verde residents expressed concern over the amount of algae and cyanobacteria on their reefs, and requested information on how to assess the sources of damage and what to do to clean it up. They have switched from use of poisons to nets in order to preserve their resources and the entire island lives from aquarium fish collection and recognizes that maintaining healthy and diverse corals and fish are the basis of their future. They have their act together, and the Barangay Captain requested help to clean up the area. Isla Verde has one of the highest use of solar panels in the Philippines. However even if all local nutrient sources are cleaned up, the reef is likely to be threatened by stresses coming from the nearby mainland of Luzon. The area of Luzon just to the north is composed of steep, deforested, and eroding hillslopes which are a major source of turbidity. Batangas Bay, to the northwest, was observed to be severely polluted by sewage, garbage, and industrial effluents, and it is probable that plumes of polluted waters from Batangas are negatively impacting coral reefs on the northern side of Isla Verde. Huge masses of floating plastic garbage were seen most of the way from Batangas to Isla Verde. Much of this is thought to be dumped by the passenger boats between Batangas and Mindoro. Detailed water quality measurements along the island and the mainland are needed to identify the magnitude of the different nutrient sources which are likely to impact the reefs. When such studies are done we think it is likely that sewage treatment in the Batangas area may prove to be essential to protect the marine habitat and livelihood of Isla Verde inhabitants. This reflects an essential point in coral reef management, namely that the management unit must include the entire source area of stress to the habitat, namely all watersheds whose liquid and solid outputs can be transported to and affect the reefs (Goreau et al., in press). Management units based on boundaries drawn only around the reefs themselves cannot possibly be effective in any but the most isolated offshore reefs, and are ultimately doomed to failure. Coastal zone management will not work in the Philippines unless it is done on an integrated planning basis which includes sewage treatment and control of erosion, as well as a switch to non-destructive harvesting.
C) EL NIDO 15) South Entalula Island. This island is uninhabited, and composed of sheer vertical limestone cliffs. Corals occur along a slope with little vertical relief. The reef, while diverse in terms of species, had moderate live coral cover and extensive cyanobacterial mats on dead corals.
16) West Pangulasian Island. This island is the site of a 30 room resort opened in 1992. The island is geologically different from all the other islands in being made up of a reddish metamorphic rock with quartz veins rather than limestone. As a result this island has soil which is virtually absent on the others, and very different vegetation. The reef was off an uninhabited section of the island. The reef had very high diversity, especially of branching and plate corals, and very large colonies of boulder corals, presenting a very varied vertical topography and highly interesting diving. Dead coral surfaces were covered with cyanobacterial mats but they appeared to be somewhat less prevalent than at Entalula.
17) West Lagen Island. This island, composed of high limestone, is a construction site for a new hotel which will open in 1998. The waters were quite turbid with suspended organic matter. The island is very close to the Palawan mainland, and the area was strongly affected by eroded sediments from the areas of Palawan which were deforested by loggers around 1986. Logging has since stopped due to local pressure, but while it took place erosion into the bay increased by around a thousand fold (Gregor Hodgson, Ph.D. thesis, University of Hawaii). The area examined lies off an uninhabitable vertical cliff. The reef grows on a nearly vertical wall. Corals were dominated by very large and spectacular colonies of leafy and branching corals. These corals are extremely fragile, and preservation of the healthy shallow reef corals here will require avoiding all physical damage. With the nearby resort opening it will be crucial that divers and snorkelers be prevented from touching the corals. Fortunately the El Nido resorts make this the first point in their brochures to guests. Dead corals were covered with cyanobacteria, but due to the greater lushness of the coral growth it was less frequent than Pangulasian.
18) South Miniloc Island. This island, a steep limestone island, has a 30 room hotel, established in 1982. The reef examined lay off an uninhabited cliff to the west of the resort, along a perched submarine ridge which is periodically affected by strong currents through the narrow channel between Miniloc and Entalula. Coral development to the western side of the channel was fairly poor, and dominated by fairly small head corals. To the east the coral cover, diversity, and size increased considerably. At this site there were few cyanobacterial mats, and dead coral and rock surfaces were largely covered with encrusting red algae, some of which were affected by Coralline Lethal Disease. Disease was also seen on some corals, especially the large Porites heads, which appear to only have been affected recently.
19) South Twin Rocks. These two small islands, just east of Miniloc are frequently used by divers and snorkelers. Coral cover was moderate and fairly diverse, with interesting topographic features provided by channels between huge blocks of limestone, up to 10 metres across, which had fallen from the islands. There were only low levels of cyanobacterial growth on dead coral and rock surfaces.
20) Southeast Inambuyod Island. This island is extremely steep and uninhabited. It lies to the north of all the other sites, being furthest from the main island of Palawan and most affected by circulation from the open shelf adjoining the South China Sea, compared to the other sites which occupy a gradient into the protected waters of Bacuit Bay. Corals at this site had high diversity, but showed the highest levels of cyanobacterial overgrowth seen in El Nido, with mats not only on dead coral and rock but also actively overgrowing live corals. Towards the end of the dive, large tracts of rubble were found, and the remains of dynamite ballasts were found on the bottom.
Sewage treatment These islands represent an important extreme since the islands have very small or no populations, and the adjacent main island has very few people and is largely forested. In addition all the resorts have secondary sewage treatment plants, and the treated effluent is reused to flush the toilets, and the excess used to water the ornamental vegetation. Only under extremely rainy conditions is the effluent not completely recycled, and the excess (on Pangalusian) is discharged into the ground above a wetland. The area where this wetland drains into the sea is free of weedy algae. In contrast, an area about a hundred metres to the south, where freshwater drains from a gully into the sea, has all rocks along the shore covered with dense green mats of the high nutrient indicating algae Enteromorpha. This indicates that the sewage treatment is fully successful in preventing nutrient discharge to the coastal zone, and that natural nutrient losses from the rich soils on the geologically aberrant island of Pangulasian exceed the human caused sources from the resort. The presence of dense cyanobacterial mats on dead coral at 4 of the 6 sites in El Nido, and their generally higher abundance in the more ocean exposed sites than in the more protected sites suggests strongly that natural offshore nutrient sources are predominant. The likely source of nutrients appears to lie in upwelling of deep water from the South China Sea. This sea is likely to have unusually high ratios of phosphorus to nitrogen because nitrogen is thought to be removed by bacteria in the organic-rich and oxygen-depleted sediments derived from the large rivers draining Indo-China. Support for the role of high natural nutrients comes from observations by local divers, who find that visibility decreases dramatically in the dry season from January through April, when the water becomes very cold and massive plankton blooms turn water green and reduce visibility to only 3 meters. Thus seasonally eutrophic conditions take place even without human inputs, and the cyanobacterial mats seen may well have been stimulated by the last event which brought deep nutrient rich water into the Bay. The presence of natural nutrient sources in this area makes it especially sensitive to small increases from human sources, which are capable of pushing the stress frequency from seasonal to year-round, and would be expected to damage the reefs. The hotels in the area are doing the best job of sewage treatment we have ever encountered anywhere in the world, and their system should serve as the model for other coastal resorts everywhere in the Philippines. The Philippines has a rare and remarkable model for ecologically sound tourism already existing in its territory, and it is important that other resort areas near reefs all around the world be made aware of its importance and follow suit. DOT could take a worldwide lead by extending this model approach on a national policy scale. It is especially important that all resorts in Palawan follow suit. This area is uniquely beautiful because of its serene and dramatic topography and because of the low population and high forest cover. It needs to be kept this way to continue to be a prime high quality resort site for those who want quiet and peaceful surroundings, and the temptation to over-expand should be rigorously held in check through zoning limitations as part of the environmental management plan for the entire province of Palawan.
D) BALICASAG
21) West of island, Fish Reserve. This portion of the island is a Fish Reserve managed by the community. The reef falls with a dramatic vertical drop off from around 10 feet depth. Coral growth was prolific, highly diverse, and the topography provides spectacular diving. Reef fish populations are high. Balicasag is regarded by sport divers as the best diving in the Philippines with the exception only of Tubbataha. Branching coral cover was high in shallow water, and there were only very minor amounts of algae. On the vertical walls plate corals and soft corals dominated, and crevices had unusually large clumps of the leafy brown algae Lobophora variegata. This alga has often been an indicator of moderately high nutrients in the Caribbean, where it has overgrown and killed many corals on deeper fore-reef slopes. This alga appears to increase in concentration with increasing depth down the wall, an unusual situation also seen in some sites in the Caribbean, and a pattern which indicates that upwelling of cold nutrient rich deep waters along the vertical wall may be taking place. The lower coverage of algae in shallow water at this site appears to indicate low nutrient inputs from the land on that side.
22) East of island, Black Forest. This area has a gradual slope at around 45 degrees rather than a wall. The deep reef area is dominated by black coral, a soft coral species, rather than hard coral. Shallow waters less than 5 metres deep had very high levels of large algae as well as cyanobacteria. These included large clumps of the sand producing algae Halimeda and Galaxaura, as well as many weedy algae species. The amount of algae increased moving towards shore. Areas of rubble which had obviously been blown apart by dynamite were seen. These areas were reportedly blown up more than 10 years ago, and the adjacent areas had good coral growth which was expanding into the damaged zones.
23) North of island, the Cathedral. This area has a spectacular vertical drop off, with large amounts of fish. Numerous lines tied off from the top of the cliff slope off into deep water, reportedly holding nets used to trap night migrating shells, apparently the endangered Pearly Nautilus. The top edge of the drop off and adjacent shallow ledge is dominated by beautiful, large, and healthy colonies of branching corals with very high diversity and provides unexcelled snorkeling conditions. Live coral cover is over 90% and was the best seen at any site in the Philippines. However on moving across the shallow reef towards the shore one encounters large patches of dynamited rubble. Moving inshore the amount of large algae overgrowing corals steadily increases, until next to shore the hard bottom is more than 90% covered by thick algae. This area had the highest algae biomass, highest species diversity, and largest number of high nutrient indicating species seen at any site. It included the notorious coral killer Dictyosphaeria cavernosa, Hydroclathron clathratus, two species of Codium, two of Dictyota, Gracilaria, Laurencia, Martensia Pavona, and unknown species of gelatinous green algae and branching fleshy red algae, and cyanobacteria, among many other species.
Sewage treatment Other than Balicasag only sites near the shore on Boracay showed a great excess of large algae over cyanobacterial mats. The tremendous growth of large algae in shallow water and their strong increase from the reef edge to the shoreline indicates that this area is receiving excessive nutrient inputs from the land. The small island is densely populated by about a thousand fishermen, whose wastes released into pit latrines enter the porous fossil coral reef limestone and appear to flow into the sea. Population density is lower by the dive lodge in front of the Fish Reserve, where less algae were seen. Balicasag has extremely beautiful reefs, with a tremendous international reputation, and many dynamited areas appear to be slowly recovering, but many inshore areas are clearly being killed by eutrophication. The algae gradient clearly points to a land-based source of most nutrients, however the large Lobophora algae on the walls suggest that upwelling could also be a natural source of upwelling. Seasonal excitation of soliton waves in the Sulu Sea causes large waves of deep water to rise across this region at certain times of the year, causing cold and green water masses off reefs. Given the considerable offshore distance of this island from Bohol, and the fairly low population of the nearest shores of Panglao Island, nutrient sources from larger islands are not likely to be important. It appears that land-based sewage sources from Balicasag are fueling the eutrophication of the shallow reefs. Dry or composting toilets are needed to prevent nutrient buildup in the sea. A program is needed to provide funds for materials and technical advice to convert the population of the island to using non-polluting sewage systems if the reef and fisheries are to remain the prime attraction they are now. During this trip there was no time to check the reefs along the tourism resorts on the south side of Mactan, but divers all reported that this area had much larger amounts of algae and far fewer corals than Balicasag. It is therefore likely that the high density tourism development and lack of adequate sewage treatment has caused severe eutrophication of the tourist areas of Cebu, and that this area is extreme need of water quality monitoring and advanced sewage treatment to maintain the long term viability of tourism there.
CONCLUSIONS 1) Most reef sites examined showed moderate to high levels of algae overgrowth. Dead coral was largely overgrown with algae, preventing new corals from settling and growing, while some living corals were being killed by algae overgrowth.
2) Although most reefs still had live coral cover indicative of fair to good overall health, deterioration was clearly visible. Besides algae overgrowth at most reefs, many also showed visible negative impacts from sedimentation, cyanide damage, dynamite damage, anchor damage, sedimentation, coral diseases, or coral bleaching caused due to high sea temperatures. Most reefs had extremely depleted fish populations.
3) Most reefs with algae appeared to be largely affected by land-based sources of nutrients, as indicated by increases from the reef edge towards the shore. However in El Nido the nutrient source appeared to lie in nutrient rich upwelled waters from the South China Sea, while in deeper areas on the wall at Balicasag vertical upwelling from deep waters also appeared to be a minor local nutrient source. Algae eating sea urchins and fish were abundant at sites in Isla Verde, Boracay, and Balicasag, but were seemingly unable to control the algae. This implies that controlling sewage to protect habitat for fisheries is an essential part of reef management.
4) The presence of high levels of algae apparently stimulated by natural nutrient sources at some locations indicates that significant background nutrient sources of natural deep water origin are important in many Philippine reefs, and hence that it is even more essential to minimize land-based sources of nutrients which could quickly push the reefs into eutrophic conditions.
5) The sewage plant under construction at Boracay will not be able to reduce coastal zone nutrients to levels low enough to protect the coral reefs unless the effluents undergo tertiary treatment.
RECOMMENDATIONS
1) The Philippines should adopt coastal zone water quality standards for coral reef areas which include criteria for acceptable levels of nutrients below those which cause eutrophication of coral reefs ( 0.014 ppm available nitrogen, 0.003 ppm available phosphorus, according to Bell, and Lapointe)
2) Monitoring of coral reefs should include a focus on identifying signs of stress to corals and to reef ecosystems especially biological indicators such as algae cover of hard bottom, bleaching, and disease as well as identifying areas damaged by turbidity, and by natural (typhoon) and human (dynamite, anchors) physical damage.
3) Water quality measurements in coral reefs need to be year round to cover seasonal changes, and be spatially distributed in a way which allows the location and magnitude of land-based and offshore nutrient sources to be determined.
4) Research on nutrients and eutrophication in Philippine marine science institutions should be greatly increased, along with training for students.
5) Measurements of coliform bacteria need to be expanded to include the major coastal populations centers as well as resort areas, as these are the locations where the greatest risk to human health are to be found.
6) Public health water quality monitoring by DENR and DOH needs to be supported at a level which allows them to make the same intensive monitoring efforts now being made at Boracay in all other coastal areas with significant human populations.
7) All areas where sewage treatment plants are being used should subject the effluents to various forms of tertiary treatment in order to allow land plants to absorb nutrients before they can enter the sea. This should include use in watering lawns, ornamental vegetation, and use of natural and managed wetlands as nutrient absorbers.
8) Effluents from the Boracay sewage treatment plant should not be discharged into the sea, but used to water the golf course, with any excess applied to terrestrial vegetation, preferably in managed wetlands or to forest restoration zones inland.
9) The sewage treatment and water reuse practices used at El Nido should be required in all hotels near coral reefs.
10) Residents in poor areas which are not likely to be provided with sewers and appropriate sewage treatment plants need to be provided with funds and technical training to construct non-polluting dry or composting toilets.
11) Moorings should be used at all dive sites to avoid anchor damage, and swimmers trained to stand on or touch corals.
12) Destructive fishing practices, especially use of dynamite and poisons, need to be ended through improved enforcement and development of more sustainable alternative income generating practices for fishermen, such as those developed by the International Marinelife Alliance, Haribon, and the Philippine Association of Aquarium Fish Collectors (PMP).
13) The acceptable carrying capacities for coastal development should be defined in terms of the ability of the healthy reefs to remain intact despite land-based sources of pollution.
14) Greatly expanded public education is needed on the importance of coral reefs, the practices which damage them, and the steps needed to restore them. This should include greatly expanded publication and distribution of Save Our Coral Reefs: A Reef Care Manual for the Philippines by Don McAlester (Ocean Voice International) and Alejandro Ansula (IMA), use of videos, lectures by Philippine marine scientists, and support for local reef protection and management NGOs.
ACKNOWLEDGEMENTS This work was carried out at the invitation of the Department of Tourism of the Philippine Government. The Global Coral Reef Alliance team agreed to conduct the study on the basis of having all expenses covered, and received no salary or fee for the study. The work described could not have been carried out without the excellent logistic and technical support of those we worked with throughout this study, and the information, advice, and discussion provided by our Philippine colleagues. Although we were not able to get the names of all who helped us, we especially wish to thank the following individuals: 1) Department of Tourism: Manila: The Honorable Mina Gabor, Secretary of Tourism, Emily Bilet, Tess Fevidal , Jean , Agnes Bocar, Mignon del Rosario
The Philippine Commission on Sport Scuba Diving: Geronimo Reyes, Norman Songco, Gaudencio Pena, Alberto Herrera, Heneage Mitchell
Boracay: Edwin Trompeta, Francis Gentoral, Nelson Tungala, Teddy Oczon
Cebu: Bebot Estillove, Christine Ordesta, Macario Mercado, Leonelo Mission
Bohol: Neil Balaba, Manuel De Erio
Balicasag: Norman Balili, Nonoy Norono
Department of Environment and Natural Resources: Vicente Diaz, Roberto Bernal
Department of Science and Technology: Reynaldo Esguerra, Froilan Dorado, Andrea
2) Diving groups:
George Wegmann, Erich Gabriel, Calypso Diving, Boracay Erick Villacorte, Pangulasian Joey Lee, Miniloc Aldo Mercado, Balicasag
3) Research Institutions:
International Centre for Living Aquatic Resources Management: John McManus
University of the Philippines Marine Science Institute: Gil Jacinto Porfirio Alino Mary Lou San Diego-McGlone Helen Yap Edgardo Gomez
4) Non Governmental Organizations:
International Marinelife Alliance: Vaughan Pratt Alejandro Ansula
Haribon Foundation: Ed Thompson
Ocean Voice International: Don McAllister Jaime Baquero
Canadian Urban Institute Philippines: Francis Gentoral
5) Commercial:
Ten Knots Development Corporation, El Nido: Emmanuel Pastores, Manager, Environment and Community Development Unit Bert Sumagaysay, Resident Engineer
SGS Philippines Inc.: Jocelyn Babaan
Dames & Moore, Inc.: Senen Salacup
Nippon Jogesuido Sekkei Co. Ltd.: Tatsuyuki Kikuta Yolanda Mingoa
CEST Inc.: Jose Ilagan
6) Local residents: Diosa Labiste, Iloilo City, Panay Mrs. ?, Barangay Captain, Isla Verde Residents of Isla Verde Residents of Balicasag |
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