Fernando Siringan

University of the Philippines System | UPD · Marine Science Institute

Being archipelagic, sea level rise is a cause of climate emergency in the Philippines. Since the country’s coastlines are typically narrow, rising sea level can make the coastal plains even narrower, and thus pose a threat to more than 60 percent of the population living in the coastal zone. Even without the full impact of sea level rise, many coas...

The morphology of coral reefs provides an effective benchmark of past sea levels because of their limited vertical range of formation and good geologic preservation. In this study, we analyze the seafloor morphology around two atolls in the Philippines: Tubbataha Reef, in Palawan, and Apo Reef, in Occidental Mindoro. High-resolution multibeam bathy...

The association between clay minerals and organic carbon is pivotal for understanding transport, burial, and preservation processes of sedimentary organic carbon. However, fine-scale microscopic studies are still limited in assessing the effect of diverse clay mineral structures and properties on organic carbon sequestration. In this study, we empl...

In this study, we determine which extreme wave events were responsible for the island formation in Lumaniag Village (Philippines). Various methods were employed: field measurements; geochemical analyses; interviews; and exploration of archives about past tsunamis and intense storms.

Little is known about Benham Bank, a guyot with a highly diverse coral reef ecosystem expanse. The Benham Bank is one of several seamounts in the Philippine Rise, a ~ 48-Myr ocean island basalt complex. Recently acquired high-resolution continuous seismic profiles and existing multi-beam bathymetry reveal its internal architecture, overall morpholo...

Climate change is perhaps the greatest threat to coral reefs worldwide. However, there is spatial variation in the extent and severity of this disturbance, with offshore and well-managed reefs presumed to be less vulnerable to anthropogenic disturbance. Here, fish and benthic communities at the offshore and well-managed reefs of Apo Reef Natural Pa...

The surface trace of the East Zambales Fault (EZF) and its associated faults in the Lingayen Gulf have been previously mapped but no other characteristics were reported. This study utilized seismic reflection, multi-beam bathymetry, and side scan sonar to characterize the offshore EZF in terms of magnitudes of vertical displacement. Sequence strati...

Atoll reefs are associated with subsiding regions. In the West Philippine Sea, the Kalayaan Island Group is an emergent feature of the region's atoll reefs. In this study, we established the long-term rate of subsidence in the Pag-asa Atoll Reefs by indicators of sea level positions on the seafloor and in Pag-asa Island. For submerged indicators of...

Sea level in the Philippine Sea is influenced by climate and oceanographic variables such as the El Niño Southern Oscillation (ENSO), North Equatorial Current bifurcation latitude (NBL), and sea surface temperature (SST). Tide gauges in the eastern Philippines, namely, San Vicente, Baler, Jose Panganiban, Guiuan, and Tandag were established in 2008...

The Philippines being an archipelagic country has the fifth longest coastline in the world. Its shores are defined by varying geologic form and composition that defines how sea water could impact its configuration. Being in a tectonically active setting, the country is also affected by ground motion. Specifically, the vertical land motion (VLM) has...

Climate change is perhaps the greatest threat to coral reefs worldwide. However, there is spatial variation in the extent and severity of this disturbance, with offshore and well-managed reefs presumed to minimize the consequences. In this study, fish and benthic communities at the offshore and well-managed reefs of Apo Reef Natural Park, Philippin...

Over 30 m-sized coral boulders are scattered 45–140 m away from the edge and above high tide on a Holocene reef flat at Pasuquin, northwestern Luzon, Philippines. The boulders are overturned or tilted as indicated by the framework fossil corals in them, but have the same lithology as those along the reef edge and thus were likely broken off from th...

After the 2013 Mw 7.2 earthquake that occurred in Bohol, the shoreline specifically in Loon and Maribojoc was observed to shift seaward due to ground uplift. This study analyzes the post-earthquake shoreline movement, specifically a 12 km coastal strip in Loon and Maribojoc, and ground deformation of the West Bohol area through Sentinel-1 image pro...

Massive coral species are essential archives of past sea surface temperature (SST) records as they incorporate biological and geochemical tracers that reflect temperature variations of their living marine environment. Existing methods of reconstructing past SST data involve analyzing elemental or isotopic ratios (e.g., Sr/Ca, coralline δ18O) that a...

The 1994 Mw 7.1 Mindoro Earthquake and the 2017 Mw 5.9 Batangas Earthquake Sequence both occurred in offshore southern Batangas and devastated southern Luzon and Mindoro. These earthquakes exhibited NW-striking right-lateral slip in an area presumably defined by a WNW-striking left-lateral fault, therefore implying the existence of previously unmap...

Tropical cyclones have devastating impacts on the environment, economies, and societies and may intensify in the coming decades due to climate change. Stable water isotopes serve as tracers of the hydrological cycle, as isotope fractionation processes leave distinct precipitation isotopic signatures. Here we present a record of daily precipitation...

One of the consequences of climate change is sea level rise (SLR). Near the coast SLR varies at different locations due to the contributions from regional/local climatic and non-climatic factors. Vertical land motion (VLM) can affect the accuracy of sea level observations from tide gauges (TG) that may exacerbate coastal area inundation/flooding. T...

Despite the growing knowledge on the significance of submarine groundwater discharge (SGD), mapping its occurrence is a continuing challenge. This study explores the capability and applicability of low-cost, off-the-shelf, recreational-grade echosounders (RGES) to image different types and locate point sources of bubbly coastal SGD. Standard and sy...

Changes in shoreline positions provide a historical record for identifying causal mechanisms and adaptive responses of coastlines to a wide spectrum of sea-level change that arises either from natural or anthropogenic disturbances. This paper presents a case study of coastal change during a period of the steady rise in sea level that is coupled wit...

Typhoon Durian in November 2006 was most notable for a series of devastating lahars that buried communities at the base of Mayon volcano in Bicol, Philippines. Typhoon Durian delivered extreme rainfall that remobilized volcanic debris that caused more than ~1200 deaths and extensive property damage. Although not as deadly as the lahar, Typhoon Duri...

Tropical rivers deliver ∼60% of particulate organic carbon to the world ocean. However, compositions and loadings of sedimentary organic matter (OM) from tropical small mountainous rivers are largely unknown. Here, we provide an initial constrain on sources of sedimentary OM from 28 fluvial systems across Luzon in the Philippines by measuring total...

The offshore extension of the East Zambales Fault (EZF) and associated faults in the Lingayen Gulf have been previously mapped, however, their characteristics are still unknown. This results in significant uncertainty in earthquake hazard and risk assessment of the region. This study utilized seismic reflection, multi-beam bathymetry, and side scan...

The datasets here contain the 3D X-ray computed tomography (3DXCT) gray values and age models of coral cores Baler 2 and 3, taken from Baler, Aurora, Philippines. 3DXCT was used to analyze 5 mm-thick slabs of the coral cores. From the resulting 3DXCT images, gray values were determined per pixel from top to bottom of the slabs. The gray value profi...

In a previous study in 2016, we presented how 129 I in coral cores from the east (Baler) and west (Parola) sides of the Philippines recorded the impacts of human nuclear activities, including nuclear weapons testing, nuclear fuel reprocessing, and nuclear accidents. However, the 2016 Baler dataset only had a two-year time resolution and a crude age...

Understanding shoreline change due to engineering modifications and how it compares with the long-term trends is vital for future development plans. In this study, we focused on the Jaro Floodway, which was constructed in 2012 to mitigate the yearly floods experienced by Iloilo City. Shoreline positions were extracted from geometrically corrected h...

The construction of the Jaro Floodway in 2012 resulted to a rapid progradation of the shoreline in 8 years. This study examined the long-and short-term changes in area covered by mangroves at the river mouth area of this flood canal by utilizing historical maps (1947 and 1988), and Landsat images. A total of 44 Landsat images were used that covered...

The contribution of tropical storms to a carbonate gravel bar formation is presented for Lumaniag village, northwestern Philippines, based on field measurements, high-precision U-Th dating of Porites sp. coral boulders (longest axis > 1 m), historical records of tsunamigenic earthquakes and typhoons, and anecdotal accounts. Results of U-Th dating s...

The juvenile stage is a critical part of a scleractinian's life history as it is when they are highly vulnerable to various post-settlement mortality processes, which influence the structure of adult scleractinian assemblages. Although numerous studies have been done to understand dynamics of juvenile assemblages at shallow water reefs (SWRs), simi...

Plain Language Summary Groundwater flow from land to sea could have important coastal impacts but it is usually unrecognized. Delicate reefs may be particularly sensitive to groundwater inputs. Yet few studies have made connections between groundwater and reefs. We investigated submarine groundwater in a volcanic coastal area that hosts the world's...

The trajectory of the Kuroshio, the western boundary current in the north Pacific, influences regional climate. It intrudes into the South China Sea (SCS) through the Luzon Strait, resulting in the exchange of water, nutrients, heat, and salt between the Pacific and SCS. It has been reported that the trajectory of the Kuroshio has varied with decad...

Here, we report new estimates of local marine radiocarbon reservoir ages from northwestern Luzon Island in the Philippines, on the east side of the South China Sea. Data for two periods, through the 1940’s and the mid-Holocene, were derived from modern and fossil corals. Our results from Luzon Island show variable ΔR values, from −39 ± 25 to 337 ±...

The Pacific Decadal Oscillation (PDO) is a complex aggregate of different atmospheric and oceanographic forcings spanning the extratropical and tropical Pacific. The PDO has widespread climatic and societal impacts, thus understanding the processes contributing to PDO variability is critical. Distinguishing PDO‐related variability is particularly c...

Mesophotic coral ecosystems (MCEs) have received increasing attention in recent years in recognition of their unique biodiversity and also their potential importance as refuges from disturbance events. However, knowledge of the composition of MCEs and how they vary in space is lacking in many regions, particularly the Coral Triangle biodiversity ho...

The Verde Island Passage, lying in the “Coral Triangle” and situated between the main Philippine island of Luzon and the island of Mindoro, has been reported as the “center of the center” of shorefish diversity, yet there are no documented successful cases of marine protection. On the northern coast of Mindoro, here focusing on the municipality of...

Side scan sonar (SSS) can provide an almost photo-realistic acoustic image of the seafloor, making them an effective tool in mapping and characterizing the seafloor. In this study, seabed features identified from the images acquired by the Cmax and Humminbird SSS in the shallow water (<200 m) environments of Batangas, Mindoro, Palawan, Pangasinan,...

Submarine groundwater discharge (SGD) in reefs can be controlled regionally by geologic structures. Since such structures are poorly characterized, their general importance to SGD is likely underappreciated. This study helps fill this gap by analyzing the effects and implications of faults and associated fractures on offshore hydrogeologic processe...

Recreational-grade side scan sonars (RGSSS) have become available in recent years. They provide high-resolution imagery similar to more expensive models but has limited depth coverage. RGSSS have been used in mapping of benthic communities in rivers and shallow reefs, however, their ability to identify potential upper mesophotic coral ecosystems ha...

The South China Sea (SCS) is a biodiversity hotspot, however, most biodiversity surveys inthe region are confined to shallow water reefs. Here, we studied the benthic habitat andfish assemblages in the upper mesophotic coral ecosystems (MCEs; 30–40 m) and SWRs(8–22 m) at three geographic locations (Luzon Strait; Palawan; and the Kalayaan Group ofIs...

The Philippines is situated within the Coral Triangle marine biodiversity hotspot and supports highly diverse coral reef communities. However, Philippine reefs are exposed to many natural and anthropogenic disturbances. Consequently, mesophotic coral ecosystems (MCEs) have drawn increasing interest because of their potential significance as refugia...

The Luzon Strait (LS) hosts the largest transport of water between the Western Pacific Ocean (WPO) and the South China Sea (SCS). The transport through the strait, dominated by the westward propagation of the Kuroshio Intrusion, influences the climate and circulation of the SCS. While numerical models have investigated the interannual variability o...

The variability in reef‐fish species assemblages was examined at three geographic locations in the Philippines (Apo, Abra and Patn), each showing varying levels of disturbances (low to high) at two depths, shallow‐water reef (SWR; 8–20 m) and the upper mesophotic coral ecosystem (MCE; 30–35 m). Fish species assemblages varied among locations and be...

Mount Bulusan, the Philippines’ fourth most active volcano, erupted in February 21, 2011, sending volcanic ash and pyroclastic materials to its surrounding rivers. The waters drained into the estuary of harmful algal blooms plagued Sorsogon Bay. We aim to determine the impact of the 2011 volcanic eruption and the preceding volcanic ash emissions to...

Understanding the processes that affect coral size distributions is important because size distributions dictate the quality of functions corals provide, such as habitat provision, coastal protection, and primary production. In corals, colony partial mortality is an important demographic process affecting size distributions. Because coral partial m...

The use of micro hydropower as a source of renewable energy can help augment electricity demand in communities. However, it is necessary to know how the community near the water source perceives the technology and its possible impacts on the community. This study seeks to determine the social acceptability of establishing a micro hydropower project...

Although a major potential contributor to water and nutrient budgets, lacustrine groundwater discharge (LGD) is often neglected in most lake studies. Through electrical resistivity profiling surveys, the authors examined the possible occurrence of LGD in southern Laguna de Bay, the largest freshwater lake in the Philippines. Discrete and dispersed...

Wave set-up steepened and accentuated the storm surge during Typhoon Haiyan in November 2013 resulting in bore-like flooding with surge heights of 7 m and flow velocities reaching 5 m s− 1 on the open-sea coastal plain near Hernani. This study investigates two distinct sediment assemblages left behind by the coastal flooding associated with this su...

The Philippines is located within an area of high reef biodiversity. However, it is vulnerable to the overexploitation of marine resources, which has reduced the abundance of many species, particularly large reef fish and marine turtles in the shallow reef areas (< 30 m). There is a need to assess the populations of these marine animals in the meso...

Coral reefs in shallow and clear waters are easily seen in satellite images. However, coral reefs and coral communities may extend to depths beyond 30 meters. Mapping these features beyond the reach of satellite images are essential in management. Side scan sonars (SSS) which cost less than 1000 USD, can provide acoustic images of the seafloor to d...

Iodine-129 in coral cores provide historical records of human nuclear activities, establish or confirm coral age models, and trace environmental processes. During the time of this writing, the only published method (Biddulph et al., 2006) for measuring 129I/127(stable)I in corals requires 10-30g of sample, which can be too large for common practice...

The Indo-Pacific coral Diploastrea heliopora reveals regional multi-decadal to centennial scale climate variability using coral carbonate δ18O (δ18Oc) as a combined proxy for sea surface temperature (SST) and sea surface salinity (SSS). However, to assess the coral's full potential in resolving climatic events, an independent SST proxy would be mor...

To investigate the spatial variation in bivalve food sources along a pollution gradient and assess bivalve contribution to biogeochemical cycles in tropical coastal ecosystems, the δ¹³C and δ¹⁵N values of bivalves and their potential food sources were studied in northwestern Philippines. In a semi-enclosed embayment affected by river discharge and...

Iodine-129 is a long-lived fission product that is majorly released in human nuclear activities (HNA) such as nuclear bomb testing, nuclear fuel reprocessing, and nuclear accidents. It is a good environmental tracer and former measurements of (129)I in corals from the southern hemisphere show the increasing trend of (129)I concentrations in the mar...

The Philippine archipelago lies in the path of seasonal tropical cyclones, and much of the coast is prone to periodic inundation due to storm surges. One example is typhoon Durian, a category 3 storm that made landfall on the 30th November 2006, in Bicol province, on the east central Philippine coast. Satellite imagery from May 2007 reveal that Dur...

Pampanga Bay receives 50% of the total annual freshwater budget of Manila Bay and has the largest river sediment input. The supply of high loads of sediments has significant implications on the aquatic productivity, coastal evolution and contaminant dispersal in the bay. Sediment dispersal patterns were determined using Landsat Thematic Mapper (TM)...

Study region: Calamba and Los Baños in Laguna Province, Philippines lie between the northern part of Mt. Makiling and north shore of Laguna de Bay. Study focus: One significant activity in Laguna province is the development of the water resorts which includes hot springs resorts and spas. Presence of hot springs is due to the geothermal activities...

Proxy records of temperature from the Atlantic clearly show that the Younger Dryas was an abrupt climate change event during the last deglaciation, but records of hydroclimate are underutilized in defining the event. Here we combine a new hydroclimate record from Palawan, Philippines, in the tropical Pacific, with previously published records to hi...

Carbonate shorelines are relatively less prone to coastal erosion than siliciclastic shorelines more protected than siliciclastic shorelines because of the presence of reef flats that protect the beach from wave actions. Also, Tthese reef flats also serve as primary source of beach sediments that could sustain sediment input thereby resulting to re...

To characterize water quality in terms of dissolved elements and to investigate both the origin of the water and the source and behavior of groundwater contaminants in Metro Manila, 33 water (groundwater and surface water) samples were analyzed for ion and element concentrations, H and O isotope ratios (δD-H2O and δ18O-H2O), SO42- isotope ratios (...

We investigated the high-resolution heavy metal pollution history of Manila Bay using heavy metal concentrations and Pb isotope ratios together with 210Pb dating to find out the effects of environmental regulations after the 1990s. Our results suggested that the rate of decline in heavy metal pollution increased dramatically from the end of the 199...

The status of nitrate (NO3−), nitrite (NO2−) and ammonium (NH4+) contamination in the water systems, and the mechanisms controlling their sources, pathways, and distributions were investigated for the Southeast Asian cities of Metro Manila, Bangkok, and Jakarta. GIS-based monitoring and dual isotope approach (nitrate δ15N and δ18O) suggested that h...

Uncontrolled groundwater extraction has been proposed as the main cause of accelerated subsidence inthe delta region north of Manila Bay. However, natural autocompaction of deltaic sediment and otheranthropogenic factors also enhance subsidence, amplifying global sea-level rise and aggravating landloss, flooding, and tidal inundation. Here, we repo...