Cesar L. Villanoy

Eutrophic waters, algal bloom and fish kill in fish farming areas in Bolinao, Pangasinan, Philippines

The coastal waters of Bolinao, Pangasinan, Philippines experienced environmental changes over a 10-year period (1995-2005), the most significant effect of which was the major fish kill event in 2002 that coincided with the first reported Philippine bloom of a dinoflagellate Prorocentrum minimum. Days before the bloom, dissolved oxygen was < 2.0 mg/l in the waters that were stratified. These conditions may be linked to the uncontrolled proliferation of fish pens and cages to more than double the allowable limit of 544 units for Bolinao waters. Mariculture activities release organic matter from unconsumed feed and fecal material that accumulate in the water and sediments. In over 10 years, water quality conditions have become eutrophic with ammonia increasing by 56%, nitrite by 35%, nitrate by 90%, and phosphate by 67%. The addition of more fish pens and cages placed additional stress to this poorly flushed, shallow area that affected water quality due to changes in the water residence time.

A multi-scale biophysical model to inform regional management of coral reefs in the western Philippines and South China Sea

The health and functioning of coral reef ecosystems worldwide is in decline, and in the face of increasing anthropogenic stress, the rate of decline of these important ecosystems is set to accelerate. Mitigation strategies at regional scales are costly, but nevertheless critical, as reef systems are highly connected across regions by ocean transport of both larval propagules and pollutants. It is essential that these strategies are informed by sound science, but the inherent complexity of coral reef systems confers significant challenges for scientists and managers. Models are useful tools for dealing with complexity and can inform decision making for coral reef management. We develop a spatially explicit biophysical model for a general coral reef system. The model couples dynamics from local (10^2 m) to regional (10^6 m) scales, and explicitly incorporates larval connectivity patterns derived from sophisticated larval dispersal models. Here, we instantiate and validate the model for coral reefs in the Philippines region of the South China Sea. We demonstrate how the model can be used in decision support for coral reef management by presenting two examples of regional-scale scenario projection relating to key management issues in the Philippines: (i) marine reserve design and the recovery of fish stocks; and (ii) synergistic effects between coral bleaching and poor water quality. These scenarios highlight the importance of considering multiple stressors to reef health and patterns of larval connectivity in regional-scale management decisions.

Developing Marine Protected Area Networks in the Coral Triangle: Good Practices for Expanding the Coral Triangle Marine Protected Area System

The Coral Triangle Marine Protected Area System aspires to become a region-wide, comprehensive, ecologically representative and well-managed system of marine protected areas (MPAs) and MPA networks. The development of this system will proceed primarily through the implementation of ecological, social, and governance MPA networks at the sub-national scale. We describe six case studies that exemplify different approaches taken to develop MPA networks in the Coral Triangle region at different scales: Nusa Penida in Indonesia; Tun Mustapha Park in Malaysia; Kimbe Bay in Papua New Guinea; Verde Island Passage in the Philippines; The Lauru Ridges to Reefs Protected Area Network in Choiseul, Solomon Islands; and Nino Konis Santana Park in Timor Leste. Through synthesis of these case studies, we identify five common themes that contributed to successful outcomes: (1) the need for multi-stakeholder and cross-level management institutions; (2) the value of integrating cutting-edge science with local knowledge and community-based management; (3) the importance of building local capacity; (4) using multiple-use zoning to balance competing objectives; and (5) participation in learning and governance networks. These lessons will be invaluable in guiding future efforts to expand the Coral Triangle Marine Protected Area System, and provide important insights for MPA practitioners elsewhere.

Repeat Storm Surge Disasters of Typhoon Haiyan and Its 1897 Predecessor in the Philippines

AbstractOn 8 November 2013, Typhoon Haiyan impacted the Philippines with estimated winds of approximately 314 km h-1 and an associated 5–7-m-high storm surge that struck Tacloban City and the surrounding coast of the shallow, funnel-shaped San Pedro Bay. Typhoon Haiyan killed more than 6,000 people, superseding Tropical Storm Thelma of November 1991 as the deadliest typhoon in the Philippines. Globally, it was the deadliest tropical cyclone since Nargis hit Myanmar in 2008. Here, we use field measurements, eyewitness accounts, and video recordings to corroborate numerical simulations and to characterize the extremely high velocity flooding caused by the Typhoon Haiyan storm surge in both San Pedro Bay and on the more open Pacific Ocean coast. We then compare the surge heights from Typhoon Haiyan with historical records of an unnamed typhoon that took a similar path of destruction in October 1897 (Ty 1897) but which was less intense, smaller, and moved more slowly. The Haiyan surge was about twice the heig...

Observations of exchange between the South China Sea and the Sulu Sea

[1] The velocity and transport, with thermohaline properties, are determined from simultaneous moored time series within Mindoro, Tablas and Panay Straits that connect the South China Sea (SCS) and Sibuyan Sea to the Sulu Sea. These passages provide the only pathway for the SCS throughflow below thermocline depths and play a critical role in regulating the heat and freshwater balance within the Philippine archipelago. The upper layer in Mindoro Strait has a distinctly seasonal cycle with northward flow during the boreal summer southwest monsoon and southward flow during the winter northeast monsoon. In contrast, upper layer flow in Panay and Tablas Straits is intraseasonal. Extraordinarily strong pulses that begin at intermediate depth in the fall transition and shoal toward the sub-thermocline during the northeast monsoon are found in Mindoro and Panay Straits. These southward flows are strongly correlated to the SCS large-scale circulation and remote wind-forcing off Vietnam. Temperature and salinity in Mindoro support the SCS source of this Subtropical Water. Southward benthic flow in Mindoro and Panay act to ventilate the deeper Sulu Sea. Bottom temperatures suggest the cooler Mindoro overflow mixes with the warmer benthic waters from Tablas before exiting Panay Strait into the Sulu Sea. The 2008 mean annual total-depth transports were very small, O(0.1 Sv), although individual transport estimates of 1–2 Sv were observed in all depth layers over the year. The mooring deployment coincided with a strong La Nina when the Pacific inflow into the SCS is expected to be weaker, and subsequently transports are lower.

The nascent Kuroshio of Lamon Bay

A northward flowing current, emanating from the North Equatorial Current (NEC) bifurcation at the Philippine margin, enters Lamon Bay along Luzons eastern coast. There the NEC tropical water masses merge with subtropical water of the western North Pacific to form the Kuroshio. A northward flowing western boundary current is first observed near 16.5°N, marking the initiation of the Kuroshio. The current feeding into the nascent Kuroshio of Lamon Bay is bracketed by an anticyclonic dipole to its northeast and a cyclonic dipole to its southwest. Ship-based observational programs in the spring seasons of 2011 and 2012 detect a shift of the Lamon Bay thermohaline stratification with marked enrichment of NEC tropical thermocline water in 2012 relative to a dominant western North Pacific subtropical stratification of 2011. Temperature-salinity time series from moorings spanning the two ship-based observations identify the timing of the transition as December 2011. The NEC bifurcation was further south in May 2012 than in May 2011. We suggest that the more southern bifurcation in May 2012 induced increased NEC thermocline water injection into Lamon Bay and nascent Kuroshio, increasing the linkage of the western North Pacific subtropical and tropical thermoclines. This connection was reduced in May 2011 as the NEC bifurcation shifted into a more northerly position and western North Pacific subtropical thermocline dominated Lamon Bay stratification.

Multiscale influences on extreme winter rainfall in the Philippines

During 2007–2008, the Philippines experienced the greatest rainfall in 40 winters. We use a combination of observations (including 48 meteorological stations distributed throughout the islands, Tropical Rainfall Measuring Mission satellite-sensed precipitation, and shipboard measurements) along with a high-resolution two-way coupled ocean/atmosphere model (3 km Coupled Ocean-Atmosphere Mesoscale Prediction System (COAMPS)®) to examine this anomalous season. As expected from climatology, rainfall was greatest on the eastern side of the archipelago, with seasonal totals exceeding 4000 mm in some locations. A moderate to strong La Nina increased the rainfall across the region. But discrete precipitation events delivered the bulk of the rain to the area and coincided with intense Madden-Julian oscillation activity over the archipelago and a late February cold surge. General patterns and magnitudes of rainfall produced by the two-way coupled model agreed with observations from land and from space. During the discrete events, the 3 km COAMPS also produced high amounts of precipitation in the mountainous parts of central Philippines. Direct observations were limited in this region. However, the government reported river flooding and evacuations in Mindoro during February 2008 as a result of significant rainfall. In addition, shipboard measurements from late January 2008 (collected by the Philippines Straits Dynamics Experiment) reveal a fresh lens of water to the west of the island of Mindoro, consistent with high freshwater discharge (river runoff) into the coastal area.

Nutrient inputs from submarine groundwater discharge on the Santiago reef flat, Bolinao, Northwestern Philippines.

Submarine groundwater discharge (SGD) on the reef flat of Bolinao, Pangasinan (Philippines) was mapped using electrical resistivity, 222Rn, and nutrient concentration measurements. Nitrate levels as high as 126 μM, or 1-2 orders of magnitude higher than ambient concentrations, were measured in some areas of the reef flat. Nutrient fluxes were higher during the wet season (May-October) than the dry season (November-April). Dissolved inorganic nitrogen (DIN=NO3+NO2+NH4) and soluble reactive phosphorus (SRP) fluxes during the wet season were 4.4 and 0.2 mmoles m(-2) d(-1), respectively. With the increase population size and anthropogenic activities in Bolinao, an enhancement of SGD-derived nitrogen levels is likely. This could lead to eutrophic conditions in the otherwise oligotrophic waters surrounding the Santiago reef flat.

Nutrient mediated stress on the marine communities of a coastal lagoon (Puerto Galera, Philippines)

Abstract Puerto Galera Bay is a coastal lagoon with a variety of marine habitats and high species diversity. It is an area in the Phillippines where the growing influence of human activities is affecting the quality of its marine resources. This study examined the distribution and behaviour of nutrients and the physical hydrography of Puerto Galera Bay and determined how its physico-chemical nature affected the condition of biotic components in the bay. The relative importance of the nitrogen and phosphorus signals were used as indicators to implicate the influence of sewage and run-off into the bay. A nutrient pool accumulated in the bay as a result of low flushing rates. The interaction of hydrodynamic forcing with the biota have implications on the phytoplankton production and coral communities in the area.

Fishing mortality rates of giant clams (Family Tridacnidae) from the Sulu Archipelago and Southern Palawan, Philippines

Average size frequency distributions of Tridacna squamosa, T. gigas, Hippopus hippopus and H. porcellanus harvested from the Sulu Archipelago and Southern Palawan areas from 1978–1985 were derived from export records and a warehouse inventory of giant clam shells. Average species mortality rates (Z) were estimated and were used to approximate average fishing mortality rates (F) over the period 1978–1985. Crude estimates of exploitation rates (F/Z) indicate that populations of these species are already overexploited. These findings have serious implications in view of the fact that the Sulu Archipelago and Southern Palawan are thought to be the last strongholds of giant clams in Philippine waters.