Northwestern Luzon Research Articles

Prevalence, diversity and co-occurrence of the white spot syndrome virus, monodon baculovirus and Penaeus stylirostris densovirus in wild populations of Penaeus monodon in the Philippines

The farming of the black tiger shrimp Penaeus monodon in the Philippines relies on wild broodstock. PCR was thus used to determine the prevalence of white spot syndrome virus (WSSV), monodon baculovirus (MBV) and Penaeus stylirostris densovirus (PstDV) in a total of 178 shrimp from 6 geographically disparate locations where broodstock are captured for use in hatcheries. PCR amplicons were also sequenced to identify phylogenetic relationships of the virus haplotypes detected. Shrimp from southeastern Luzon (Camarines Norte) had the highest prevalence of each of the 3 viruses and were frequently co-infected with 2 or more viruses. No viruses were detected in shrimp from northwestern Luzon (Pangasinan). MBV was most prevalent and PstDV strains displayed the most genetic diversity. WSSV was detected at 3 sites, and a VP28 gene sequence examined was invariant and consistent with strains found in many countries, including Thailand, China, Japan, Korea, Indonesia, Iran, Brazil and Mexico. WSSV open reading frame 94 gene sequence analysis identified location-specific repeat types. MBV sequences were dissimilar to haplotypes detected in India. PstDV sequences were diverse and included 2 lineages detected either in Australia or in the United States, Ecuador, Taiwan, China and Vietnam. The PCR data confirmed that WSSV, MBV and PstDV are endemic in P. monodon in the Philippines but that populations at some locations might remain free of infection.

Determining the suitability of gold bulking villages articulated to the Lepanto gold district of Northwestern Luzon with the aid of WorldView2 satellite imagery

This paper presents a suitability model of bulking villages in the Lepanto gold district using the weighted overlay technique. An as an alternative to more environment-deterministic modelling in GIS, an attempt is made to use a hybrid of both environmental variables with social variables. The resulting raster model was then overlain on image enhanced WorldView2 scenes to remote sense high probability sites for bulking villages. Two known sites were also tested if their locations conformed to the gold bulking model. Danac site was more conducive to accommodate transshipment of bulkier loads while the Apaya site was more conducive to spotting ship arrivals on the coast. The variation is arguably connected to the latitude of agency of the upland gold miners vis a vis the lowland coastal polities.

Mesozoic radiolarian faunas from the northwest Ilocos Region, Luzon, Philippines and their tectonic significance

AbstractNorthwestern Ilocos Norte in Luzon, Philippines, exposes cherts, peridotite and a variety of metamorphic rocks including chlorite schist, quartzo‐feldspathic schist, muscovite schist and actinolite schist. These rocks are incorporated within a tectonic mélange, the Dos Hermanos Mélange, which is thrust onto the turbidite succession of the Eocene Bangui Formation and capped by the Upper Miocene Pasuquin Limestone. The radiolarian assemblages constrain the stratigraphic range of the cherts to the uppermost Jurassic to Lower Cretaceous. Stratigraphically important species include Eucyrtidiellum pyramis (Aita), Hiscocapsa acuta (Hull), Protunuma japonicus (Matsuoka & Yao), Archeodictyomitra montisserei (Squinabol), Hiscocapsa asseni (Tan), Cryptamphorella conara (Foreman) and Pseudodictyomitra carpatica (Lozyniak). The radiolarian biostratigraphic data provide evidence for the existence of a Mesozoic basinal source from which the cherts and associated rocks were derived. Crucial to determining the origin of these rocks is their distribution and resemblance with known mélange outcrops in Central Philippines. The mélange in the northwestern Ilocos region bears similarities in terms of age and composition with those noted in the western part of the Central Philippines, particularly in the islands of Romblon, Mindoro and Panay. The existence of tectonic mélanges in the Central Philippines has been attributed to the Early to Middle Miocene arc–continent collision. This event involved the Philippine Mobile Belt and the Palawan Microcontinental Block, a terrane that drifted from the southeastern margin of mainland Asia following the opening of the South China Sea. Such arc–continent collision event could also well explain the existence of a tectonic mélange in northwestern Luzon.

Raised Coral Reefs at Bolinao, Northwestern Luzon Island of the Philippines

Raised Coral Reefs at Bolinao, Northwestern Luzon Island of the Philippines

WorldView2 satellite imagery in remote sensing a past gold trading trail in Luzon: Testing ethnohistory-based and GIS-based models

This article examines the application of image enhancement techniques on high resolution and multi-spectral WorldView 2 satellite images in aid of remote sensing a past gold trading trail in Northwestern Luzon that was used from the PreSpanish Contact Period 10th to 16th c and the Spanish Contact Period (17th to 19th c). In delineating the corridor for the research, several ethnohistorical accounts were followed as interlocutors. The article posits that segments of the Aringay-Tonglo-Balatok gold trail are still visible on the landscape while other segments may have been converted to contemporary farm-to-market roads. Identification of the segments was made possible by application of image enhancement techniques on WorldView2 satellite imagery including resolution merge using Brovey transform, unsupervised classification using a fusion of built-up index and vegetation index. Satellite band combination for mining operations (yellow-NIR1-red edge), modified false color Infrared (NIR1-green-blue), and soils and constructions (red-blue-yellow) have also been of immense utility.

Philippine mossy forest stick insects: first record of the genus Otraleus Günther, 1935 in the country, with four new species, and the new genus Capuyanus gen. nov. (Phasmida, Diapheromeridae, Necrosciinae)

The genus Otraleus Günther, 1935 is recorded from the Philippines for the first time. Four new species, Otraleus bellemansae sp. nov., O. applai sp. nov., O. christianae sp. nov. and O. elizabethae sp. nov., are described from the highlands of Northwestern Luzon. The characters allowing separation from O. hypsimelathrus Günther, 1935 and O. labanrataensis Soew-Choen, 2016, are given. A new genus closely related to Otraleus, Capuyanus gen. nov., is described with a single species, C. magwilangi sp. nov., as type-species. An identification key and distribution maps are provided for all species.

Coral-based Holocene sea level of Paraoir, western Luzon, Philippines

Shallow-water corals are crucial natural archives for reconstructing deglacial sea-level changes. However, significant discrepancies exist between sea-level records from different places. Here we present recently acquired 230Th-dated coral ages between 10,256±50yr BP and 6654±29yr BP (before 1950 AD) from Paraoir, western Luzon, Philippines to document deglacial sea-level rise of the western Pacific. The results indicate that the Paraoir reef started growing 10.3kyr BP from about 29m below present sea level, and reached 8m below the PSL at 7.2kyr BP. The Paraoir sea-level records are consistent with those of northwestern Luzon and the western Australia coast; both of which are coral-based records in continental or island arc settings. But sea levels of Luzon are significantly higher than those of Tahiti, a basaltic island on oceanic crust. We propose that the differences in sea level between the Philippine and Tahiti result from spatial variations of glacial isostatic adjustment of the two sites.

Where We Stand: A Synthesis of Status Reports of Mangroves in Northwestern Luzon

Northwestern Luzon has over 8,600 km of the Philippine shoreline, and is composed of 8 cities, 73 municipalities and 909 barangays. It is part of the northern section of the West Philippine Sea biogeographic region and is home to over 14.5 million individuals (14,240,907), around 10% of whom live in coastal areas (Table 26). Table 26. Provinces in northwestern Luzon showing the total (and % coastal population) per province

E. State of the Mangroves in Pangasinan

Pangasinan is one of the largest provinces in Region I and in the country. It is located in northwestern Luzon, bounded in the north by La Union province, in the east by Nueva Ecija province, in the south by Tarlac province, and in the west by Zambales province. Pangasinan covers a total land area of 536,818 ha with four cities, 44 municipalities and 1,364 barangays. Its 285.66 km coastline extends from San Fabian in the east to Infanta in the west, and is the longest in the region covering 2 cities, 12 municipalities and 123 coastal barangays. Most of the cities and municipalities lie along the historic Lingayen Gulf and Dasol Bay along the West Philippine Sea with an area of approximately 428,400 ha. !e Gulf, along with 9,000 ha of communal bodies of water, is a major shing ground of the coastal communities. Pangasinan is the third most populous province in the country and in Region I with a population of 2,906,085 people as of 2013. About 29% of the population resides in the coastal areas comprising around 135,000 families who are highly dependent on shing as their main source of livelihood and income.

Geochemical and mineralogical characterizations of altered bentonite interacted with alkaline fluids, northwestern Luzon, Philippines

Geochemical and mineralogical characterizations of altered bentonite interacted with alkaline fluids, northwestern Luzon, Philippines

Modeling the long-term variability of phytoplankton functional groups and primary productivity in the South China Sea

Primary productivity (PP) and phytoplankton structure play an important role in regulating oceanic carbon cycle. The unique seasonal circulation and upwelling pattern of the South China Sea (SCS) provide an ideal natural laboratory to study the response of nutrients and phytoplankton dynamics to climate variation. In this study, we used a three-dimensional (3D) physical–biogeochemical coupled model to simulate nutrients, phytoplankton biomass, PP, and functional groups in the SCS from 1958 to 2009. The modeled results showed that the annual mean carbon composition of small phytoplankton, diatoms, and coccolithophores was 33.7, 52.7, and 13.6 %, respectively. Diatoms showed a higher seasonal variability than small phytoplankton and coccolithophores. Diatoms were abundant during winter in most areas of the SCS except for the offshore of southeastern Vietnam, where diatom blooms occurred in both summer and winter. Higher values of small phytoplankton and coccolithophores occurred mostly in summer. Our modeled results indicated that the seasonal variability of PP was driven by the East Asian Monsoon. The northeast winter monsoon results in more nutrients in the offshore area of the northwestern Luzon Island and the Sunda Shelf, while the southwest summer monsoon drives coastal upwelling to bring sufficient nutrients to the offshore area of southeastern Vietnam. The modeled PP was correlated with El Nino/Southern Oscillation (ENSO) at the interannual scale. The positive phase of ENSO (El Nino conditions) corresponded to lower PP and the negative phase of ENSO (La Nina conditions) corresponded to higher PP.

Geohazards, Tropical Cyclones and Disaster Risk Management in the Philippines: Adaptation in a Changing Climate Regime

Climate change, involving both natural climate variability and anthropogenic global warming, has been a major worldwide concern, particularly with the publication of the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change. Considering the archipelagic nature of the Philippines and its being a very minor emitter of greenhouse gases, adaptation to climate change has been the Government’s national policy. The importance of expediting these climate change-related adaptation measures was highlighted by a string of geo-meteorological-related disasters, specifically triggered landslides and floods consequent to Typhoon Parma that hit the country in 2009. We present the geologic conditions that rendered the affected areas, especially in northwestern Luzon, extremely vulnerable to the existent hazards, the meteorological conditions that set off the disaster and the different initiatives that the government and local communities have taken to further prepare the people for possible future disasters. Recognition of the pertinent issues and the extant challenges points to the urgent need for mainstreaming both geo-meteorological-related disaster risk management and climate change adaptation measures in the light of changing climate conditions.

An abrupt backreef infilling in a Holocene reef, Paraoir, Northwestern Luzon, Philippines

We describe a sudden backreef infilling at the west coast of Luzon, Philippines, which occurred after 324 ± 12 yr ago (year BP, before 1950 AD). Results of 30 230Th-dated fossil corals from the surface and 5 cores, 17–29.1 m in length, recovered from a Holocene reef at Paraoir show that the reef flat developed in two stages. The reef margin is dated at 10,256 ± 50 (2σ) yr BP at 23.9 m below mean sea level (MSL) and about 6,654 ± 29 yr BP at 3.7 m below MSL with ages increasing with depth. The reef flat was formed with sediments of 818–324 yr BP old, which do not follow an age–depth correlation. The evidence suggests that a backreef moat remained empty throughout the buildup of the reef for about 6 kyr and was filled abruptly with a 26-m-thick succession of rubble and bioclastics by an extreme wave event (EWE) after 324 ± 12 yr BP. Field evidence, historical records, and tsunami simulation suggest the EWE sedimentation was likely caused by a single severe tropical cyclone, although the possibility of tsunami is not ruled out. The Paraoir reef flat was built up in a mode different from previously reported cases of Holocene reefs.

Decadal variability of chlorophyll a in the South China Sea: a possible mechanism

Four climatologies on a monthly scale (January, April, May and November) of chlorophyll a within the South China Sea (SCS) were calculated using a Coastal Zone Color Scanner (CZCS) (1979-1983) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) (1998-2002). We analyzed decadal variability of chlorophyll a by comparing the products of the two observation periods. The relationships of variability in chlorophyll a with sea surface wind speed (SSW), sea surface temperature (SST), wind stress (WS), and mixed layer depth (MLD) were determined. The results indicate that there is obvious chlorophyll a decadal variability in the SCS. The decadal chlorophyll a presents distinct seasonal variability in characteristics, which may be as a result of various different dynamic processes. The negative chlorophyll a concentration anomaly in January was associated with the warming of SST and a shallower MLD. Generally, there were higher chlorophyll a concentrations in spring during the SeaWiFS period compared with the CZCS period. However, the chlorophyll a concentration exhibits some regional differences during this season, leading to an explanation being diffi cult. The deepened MLD may have contributed to the positive chlorophyll a concentration anomalies from the northwestern Luzon Island to the northeastern region of Vietnam during April and May. The increases of chlorophyll a concentration in northwestern Borneo during May may be because the stronger SSW and higher WS produce a deeper mixed layer and convective mixing, leading to high levels of nutrient concentrations. The higher chlorophyll a off southeastern Vietnam may be associated with the advective transport of the colder water extending from the Karimata Strait to southeastern Vietnam.

ASSESSMENT OF COASTAL VULNERABILITY TO SEA LEVEL RISE OF BOLINAO, PANGASINAN USING REMOTE SENSING AND GEOGRAPHIC INFORMATION SYSTEMS

Abstract. A number of studies assessing the vulnerability of Southeast Asia to climate change have classified the Philippines as one of the vulnerable countries in the region. Bolinao, Pangasinan is a municipality located in northwestern Luzon, situated in the western part of the Lingayen Gulf and is bounded on the north and west by the South China Sea (West Philippine Sea). Recent studies have verified the varying trends in sea level across the South China Sea, which is considered as one of the largest, semi-enclosed marginal seas in the northwest Pacific Ocean. Three barangays (villages) were included in the study: (1) Luciente 1.0, (2) Concordia and (3) Germinal. The Socioeconomic Vulnerability Index (SVI) was computed based on population, age, gender, employment, source of income and household size, which were gathered through a qualitative survey in the selected barangays. The Coastal Vulnerability Index (CVI) described the physical vulnerability of these coastal communities based on recorded sea level anomalies and significant wave heights of multiple satellite altimetry missions, coastal topography derived from the 25-m SRTM digital elevation model (DEM), bathymetry from WorldView-2 and additional elevation data from terrestrial laser scanning surveys. The research utilized merged satellite altimetry data downloaded from the Radar Altimetry Database System (RADS), which covered the period from 1991–2010. The SVI and CVI were calculated and evaluated in ArcGIS. The SVI and CVI were integrated to determine the Total Vulnerability Index (TVI), which characterized the vulnerability of the three barangays in five classes, from very low to very high vulnerability.

Sea-level rise and coral-reef development of Northwestern Luzon since 9.9 ka

Coral reef growth and relative sea-level record for the early mid-Holocene are established from three boreholes drilled on a raised Holocene reef at Currimao, northwestern Luzon, Philippines. Age control is provided by 230Th dates of 13 corals mostly in living position. The cores cover a depth interval from 3.8 m above to 26.7 m below present mean sea level (MSL) and consist of four lithofacies including (1) reef facies, (2) bioclastic facies, (3) clayey facies and (4) tuffaceous facies. The ages of dated corals vary from 6588 ± 27 ya at 1.4 m below MSL to 9855 ± 42 ya at 22 m below MSL. Results of this study indicate that the reef started growing about 9.9 ka when the minimum sea level, relative to the western Luzon coast, was about 27 m below MSL after tectonic correction. During 9.2–8.2 ka, reef accretion rate was as high as 10–13 m/ky. Coral reef developed to near paleo-sea level at about 6862 ± 28 ya and emerged due to tectonic uplift. The sea-level curve of Currimao is generally similar to that of the Western Australia coast but at least 8–11 m higher than that of Tahiti from 10 to 8.5 ka.

Influence of tropical cyclones on seasonal ocean circulation in the South China Sea

The seasonal variability of South China Sea (SCS) ocean circulation influenced by tropical cyclones (TCs) is studied by using satellite QuikSCAT wind data, Sverdrup theory, and a reduced gravity model. TCs can induce a positive (negative) wind stress curl in the northwestern (southeastern) SCS in summer and a positive wind stress curl for the whole SCS in winter. With these wind stress curls induced by TCs, the cyclonic gyre in the northern SCS and the anticyclonic gyre in the southern SCS are intensified in summer. In winter, the cyclonic gyre in the northern SCS is intensified and the gyre in the southern SCS is weakened except in November and December when both gyres are enhanced. The model results show that the dipole structure off central Vietnam in summer is intensified and the eddy off northwestern Luzon Island in winter is weakened by TCs. The present paper shows that TCs can affect both large‐scale and mesoscale SCS ocean circulation, suggesting that studies including the effect of TCs are necessary to help improve our understanding of SCS ocean circulation dynamics.

First discovery of fossil Nautilus pompilius Linnaeus, 1758 (Nautilidae, Cephalopoda) from Pangasinan, northwestern Philippines

A chambered nautilus shell from the early Pleistocene deep-water sediments in the Bolinao area of Pangasinan province, northwestern Luzon, Philippines is described. Although the shell is fragmentary, the shell features indicate that the specimen is referable with reservation to the extant Nautilus pompilius Linnaeus, 1758. This finding represents the first and oldest fossil record of N. pompilius and complements the Plio-Pleistocene gap of the nautiloid fossil records. Taphonomic implications for Cenozoic nautiloids were briefly discussed.

Foraminiferal responses to upwelling variations in the South China Sea over the last 220 000 years

Late Quaternary benthic and planktonic foraminiferal and isotopic data were obtained from two sediment cores in the present upwelling areas of the South China Sea: Core 17928 off northwestern Luzon and Core 17954 off eastern Vietnam. Quantitative analyses of foraminifera in the two cores revealed the foraminiferal responses to paleoceanographic changes over the last 220 000 years. High productivity species such as Neogloboquadrina dutertrei, Bulimina acculeata, Uvigerina peregrina, Melonis barleeanus and Chilostomella oviodea displayed high abundance during interglacial periods in Core 17954 and during glacial periods in Core 17928. Correspondingly, variations in benthic foraminifera accumulation rates, the ratio of infaunal to epifaunal benthic foraminifera and the presence of the benthic foraminifers Cibicidoides, Miloilids and Oridorsalis umbonatus, all indicate that bottom water was oxygen-rich and oligotrophic during glacial periods off Vietnam (Core 17954) but such bottom conditions occurred during interglacial periods off Luzon (Core 17928). Sea-surface temperature results from planktonic foraminifera transfer function and variations in the abundance of planktonic foraminifera, typical tropical species Globigerina sacculifer, tropical–subtropical species Globorotalia menardii, Globigerinoides ruber, and Pulleniatina obliquiloculata, transition species Globorotalia inflata and Arctic species Neogloboquadrina pachyderma, indicate an increase in cool waters during marine isotope stage (MIS) 5, except for MIS 5.5, and glacial intervals in the cores 17954 and 17928, respectively. The ratios of mixed-layer/thermocline dwelling species and depth of thermocline (DOT) estimates using transfer function suggest that the DOT was shallower during the interglacial than the glacial periods off Vietnam (Core 17954), but the DOT was shallower during the glacial periods off Luzon (Core 17928). Our results show that in the glacial periods lower sea surface temperature, shoaled thermocline, and high productivity increased off northwestern Luzon (Core 17928), and that, on the contrary, similar event occurred in the interglacial off Vietnam (Core 17954). These differences in the upper water column structure and productivity in the two areas were induced by coastal upwelling, which in turn is driven by monsoons. The intensity of upwellings is also closely related to the evolution of the eastern Asian monsoon. Therefore, we conclude that differences in the upwelling intensity in the two sites indicate strengthening of winter and summer monsoon during the glacial and interglacial periods, respectively.

Current Status of the Golden Apple Snail in the Ifugao Rice Terraces, Philippines

ABSTRACT The golden apple snail (GAS) was introduced in the Philippines between 1982 and 1984 to supplement sources of food protein of low-income Filipino farmers. However, in 1986, it began to damage heavily rice farms in northwestern Luzon. Its rapid multiplication and wide distribution threaten rice production and food security in the country. This study led by scientists and researchers of the DA-PhilRice focused on farmers' KAP (knowledge, attitudes and practices) survey and snail sampling. The current status and management of GAS in the IRT (Ifugao Rice Terraces) was determined with emphasis on ecological, and socioeconomic aspects. Farm interviews were conducted using a pretested questionnaire translated into Iloko (the local dialect), using a list of key issues but not limited by it. In-depth interviews gathered greater insights on farmers' perceptions of the GAS problem. These were aimed at developing seasonal and historical profiles, and interaction matrices describing GAS development in the IRT. Secondary data from the MAO, CECAP, ITC, DA and key informants in the barangays were gathered to validate the interview data. Randomly selected and interviewed were 127 farmers from the 26 barangays in the Ifugao municipalities of Banaue, Hungduan, and Mayoyao. Women outnumbered men. Majorities of the farmers had average literacy and were aged 31–70 years old. They had substantially long rice farming experiences aside from non-farm activities such as woodcarving. Farmers ranked GAS as their main pest after earthworms and rats. GAS had invaded the IRT because of human intervention and lack of adequate basic knowledge of the pest. Farmers' perceived a yield loss of 41–50% caused by GAS. Farmers in the IRT use many indigenous technologies, but their potential and integration will have to be validated. GAS was the only snail pest species found in the IRT irrespective of elevation. GAS females always outnumbered males, but operculum size varied with shell size, and could not be related to sex. The most common color encountered in the GAS samplings was golden brown. Specific technologies to manage GAS are needed in the IRT taking into account the indigenous technology and farmers' knowledge, rather than making blanket recommendations which lowland farmers now use for GAS management. This is possible through the farmer-scientist participatory research, extension and training approach. The existing National IPM program of the Department of Agriculture could further strengthen this approach to promote other uses of GAS through the farmers' field school.