00. Ocean Decade - Philippines
Permanent URI for this communityhttps://repository.unesco.gov.ph/handle/123456789/7
The UNACOM Online and Digital Enabling Library and Index is developed to support the alignment of research, investments, and community initiatives toward contributing to a well-functioning, productive, resilient, sustainable, and inspiring ocean. The goal is to enable the government, partner agencies, and UNESCO to develop more robust Science-Informed Policies and facilitate a stronger Science-Policy Interface through the gathered data, information, and knowledge related to the Ocean Decade in the Philippines.
Particularly, it aims to:
Particularly, it aims to:
- Gather and index all publications, reports, policies, laws, legislations, articles, and other documents of the Philippine National Committee on Marine Sciences (NCMS) related to the Ocean Decade.
- Disseminate and promote these publications, reports, policies, and other documents on the initiatives and actions to address the Ocean Decade challenges.
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- A synthesis and review of historical eruptions at Taal Volcano, Southern Luzon, PhilippinesDelos Reyes, Perla J.; Bornas, Ma. Antonia V.; Dominey-Howes, Dale; Pidlaoan, Abigail C.; Magill, Christina R.; Solidum, Renato Jr. U. (Elsevier BV, 2018-02)The Philippines is an area of persistent volcanism, being located in one of the most tectonically active regions in the world. Taal Volcano in Southern Luzon is the second most frequently erupting volcano of the 24 active volcanoes in the Philippines. A comprehensive and critical review of published and unpublished references describing the 33 known historical eruptions of Taal may provide answers to knowledge gaps on past eruptive behavior, processes, and products that could be utilized for hazard and risk assessment of future eruptions. Data on the prehistoric eruptions and evolution of Taal Caldera and subsequent deposits are limited. Only four caldera-forming events were identified based on four mapped ignimbrite deposits. From oldest to youngest, these are the silicic Alitagtag (ALI) and Caloocan (CAL) Pumice Flow deposits, the dacitic Sambong Ignimbrite (SAM), and the basaltic-andesitic Taal Scoria Flow, renamed Scoria Pyroclastic Flow (SFL). Except for SFL with 14C dating yielding 5380 ± 70 to 6830 ± 80 ky, there are no age constraints or estimates of extent for the three older deposits. A comprehensive review of the historical eruptions of Taal Volcano is the central element of this paper and includes all eruptions from AD1572 (the first known historic event) to AD1977. Eruption styles and the interplay between processes and products for each eruption are reinterpreted based on the narrative descriptions from all available accounts. A change of classification of eruption styles and eruptive products is undertaken for some events. At least nine reported eruptions were deemed uncertain including the AD1605-AD1611 event (more likely seismic swarms), the AD1634, AD1635, and AD1645 (may simply be solfataric or hydrothermal activity) events, and the AD1790, AD1825, AD1842, AD1873 and AD1903 events that were listed in recent published and unpublished documents but do not provide any details to describe and confirm the eruptions except for listing a default VEI of 2. Pyroclastic density currents brought devastating impacts to the communities around Taal during the AD1749, AD1754, AD1911 and AD1965 eruptions and remain the biggest threat in the case of renewed volcanic activity. Significant implications for aviation are implied by the narrative of tephra fall dispersal towards Manila, the central gateway of international aviation operation in the Philippines, during the AD1754 eruptions. The dispersal of tephra in the event of an explosive eruption at Taal towards Metro Manila would have catastrophic effects to transport, utilities and business activity, potentially generating enormous economic losses. Hazards from earthquake events associated with future volcanic activity may also have localized impacts. Occurrences of liquefaction phenomena as a consequence of severe ground shaking are interpreted during the AD1749, AD1754, and AD1911 eruptions. More work needs to be done to develop a comprehensive understanding of the hazards and risks associated with an explosive eruption at Taal Volcano, especially related to the older Quaternary caldera-forming eruptions that produced large-volume pyroclastic deposits that are extensively distributed and exposed. We acknowledge that there may be additional prehistoric eruptions where the eruptive products have not been preserved, recognized or reported. Events that cannot be verified or do not have sufficient details to confirm the eruption, have been downgraded to “uncertain”. Eruptions that are confirmed with identified dispersal and emplacement of tephra fall and other eruptive deposits, as interpreted from narrated records, could provide crucial information that may be utilized in hazard assessment.
- Estimation of the vertical phytoplankton distribution in the Philippine Sea: Influence of turbulence following passage of typhoonsCordero-Bailey, Kristina S.A.; Almo, Aldwin T.; David, Laura T.; Yñiguez, Aletta T. (Elsevier, 2022-11)The subsurface chlorophyll-a maximum (SCM) is a phenomenon that contributes significantly to the total primary production of the open ocean but it is not observable from remote sensing, thus primary production based on satellite information is highly underestimated. In a highly dynamic region such as the Philippine Sea, turbulence caused by tropical storms may exert significant impact on the SCM feature. In this study, we attempt to estimate the vertical phytoplankton profile in the Philippine Sea from remote sensing images by applying a generic quantitative approach. Generalized Additive Models (GAM) followed by Generalized Linear Models (GLMs) were used create predictive equations between response variables (Chl-a profile parameters) and predictor variables (RS parameters). GAM was able to predict integrated Chl-a biomass using photosynthetic active radiation (PAR), wind speed and wind stress, the depth of the Chl-a peak using surface Chl-a, wind speed and wind stress, and the baseline Chl-a concentration using sea surface temperature, sea surface salinity and PAR. GLM found wind stress and wind speed as significant predictors for integrated Chl-a biomass, while surface Chl-a, wind speed and wind stress were significant predictors for depth of the Chl-a peak. When the predictive equations were applied to 2020 monthly satellite images, they were seen to adequately estimate the offshore spatial distribution of the two Chl-a parameters. Increased turbulence due to high wind speed and wind stress during passage of tropical storms was seen to result in shallowing of the SCM and subsequent increase in Chl-a within the water column. These equations could be refined if long-term observational data was available. The capacity to estimate vertical distribution of primary productivity in the Philippines provides a means to better understand fisheries productivity and biogeochemical cycling in the region.
- Characteristics of marine heatwaves in the PhilippinesEdullantes, Brisneve; Concolis, Brenna Mei M.; Quilestino-Olario, Raven; Atup, Dale Patrick D.; Cortes, Aiza; Yñiguez, Aletta T. (Elsevier, 2023-09)Marine Heatwaves (MHWs) are prolonged, discrete, and anomalously warm events, which have recently gained global attention due to their far-reaching effects and reported impacts. Although intensive studies have been carried out at global and regional scales, these events remained understudied in the Philippines – a country with high marine biodiversity. The Philippines is highly vulnerable to the impacts of these extreme events as it lies in the western boundary of the Pacific that is considered as a hotspot for MHWs. The present study used multi-year climatic sea surface temperature (SST) record to detect MHWs in the Philippines. The detected events were then characterized using the standardized metrics. Linear trend analysis was conducted to determine the magnitude and direction of the change of the MHW metrics over time. Decadal trend revealed that MHWs in the Philippines significantly increased from seven MHWs in the 1980s to 37 MHWs in the last decade. Moreover, increased duration was remarkable in 2020 with 276 MHW days. MHW frequency and duration were increasing at a rate almost twice as its neighboring waters. Intensities did not significantly increase with time, but the highest SST anomaly is associated with El Niño Southern Oscillation. Furthermore, the eastern and western region of the Philippines is vulnerable to MHWs, but hotspots are mostly confined in the West Philippine Sea and western tropical Pacific. An in-depth investigation of the drivers of MHWs is recommended to understand the physical mechanisms of the development of these extreme thermal events in the Philippine seas. The findings have significant implications for coastal marine resource management, highlighting the need for adaptive management strategies and increased monitoring and research efforts to mitigate the impacts of MHWs on marine ecosystems and local economies in the Philippines.
- Multiple severe storms revealed by coral boulders at Pasuquin, northwestern Luzon, PhilippinesGong, Shou-Yeh; Liu, Sze-Chieh; Siringan, Fernando P.; Gallentes, Adonis; Lin, Han-Wei; Shen, Chuan-Chou (Elsevier, 2022-11-15)Over 30 meter-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 there. The dimensions of boulders larger than 3 m were calculated from 3D models constructed by photogrammetry. Their volumes range from 10 to 53 m3. Assuming 2.1 g/cm3 for wet density, weights of boulders would range from 21 to 110 metric tons. Boulders of such size and weight can't be moved by normal waves, and thus must have been dislodged by extreme wave events (EWEs). Small and well-preserved corals found on the surface of seven boulders were collected for 230Th dating to reconstruct the timing of displacement. The ages of corals are 1781.6 ± 1.9, 1903.4 ± 2.7, 1945.8 ± 1.2, 1956.9 ± 1.2, 1956.75 ± 0.99, 1978.1 ± 1.5 and 2002.78 ± 0.88 CE, respectively. These ages are considered to constrain the timing of boulder displacement from the reef edge. We propose that typhoon-induced EWEs were responsible for the displacement of these boulders at Pasuquin.
- Ground deformation analysis caused by post-2013 earthquake in Bohol, PhilippinesBauzon, Ma. Divina Angela I.; Reyes, Rosalie B.; Blanco, Ariel C.; Siringan, Fernando P. (Springer Science and Business Media LLC, 2022-08-16)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 processing techniques. From October 2014 to April 2018, the DSAS linear regression shoreline rates were − 4.36 m/yr in Loon and − 1.69 m/yr in Maribojoc, indicative of a landward movement of 91.4% and 88.8% of shoreline transects in Loon and Maribojoc, respectively. PSInSAR revealed varying rates of VLM in the study area from October 2014 to December 2018 such that Loon and Maribojoc exhibit a subsidence rate of − 2 to − 8 mm/yr. The correlation between the shoreline retreat and the land subsidence in the study area is 87%, indicating a possible elastic rebound after the earthquake. The portion of Tagbilaran City on its northern side exhibits land subsidence of − 2 to − 6 mm/yr while its southern side exhibits land uplift of 0–2 mm/yr. The relative sea level fall from TGSL measurements indicates an uplift in the location of the tide gauge in Tagbilaran City.
- Co-occurrence of a marine heatwave and a reported tomato jellyfish (Crambione mastigophora Maas, 1903) bloom in March 2020 at El Nido, Palawan, PhilippinesQuilestino-Olario, Raven; Concolis, Brenna Mei M.; Atup, Dale Patrick D.; Cortes, Aiza; Yñiguez, Aletta T.; Edullantes, Brisneve (The Plankton Society of Japan/The Japanese Association of Benthology, 2023-05-31)Globally, observations on marine species during marine heatwaves (MHWs) help outline the scope of the MHW’s possible biological effects. In line with this effort, this paper presents a 2020 MHW that coincided with a reported ‘tomato jellyfish’ (Crambione mastigophora Maas, 1903) bloom on 23 March 2020 in the Corong-Corong Bay of Palawan, Philippines. Detecting a moderate MHW from 21 March to 04 April 2020, the analysis of sea surface temperatures revealed that most areas surrounding the bloom site attained their peak positive anomalies on the same day as the reported bloom. Certain physical mechanisms present in the first quarter of 2020 may have played a role in the occurrence of both events: the presence of cyclonic eddies and parallel monsoonal winds alongshore can induce upwelling which promotes biological productivity in surface waters, while the observed weakening of winds have been associated with anomalous warming of the sea surface. Further studies are still highly recommended to determine the exact causes of the jellyfish bloom and what conditions make it more likely to happen during MHWs. However, if the C. mastigophora is hypothetically able to continually bloom amidst warming temperatures, the increasing trend of MHW frequency and intensity in the West Philippine Sea (where the reported bloom site is situated) may consequently yield more future co-occurrences. This paper aims to hopefully contribute to the existing knowledge of possible biological impacts associated with extreme marine events, especially in the Philippine context where both jellyfish blooms and MHWs are understudied.The authors would like to express sincere gratitude to the anonymous reviewers whose comments and suggestions helped improve and clarify this manuscript. The authors would also like to thank Mr. Alimar Amor for his permission on the still photos in Figs 1c and 1d from his recorded jellyfish bloom video on 23 March 2020. This paper is also made through the funding of DOST̶ Philippine Council for Industry, Energy, and Emerging Technology Research and Development under the Survey of Heatwaves in the Philippine Seas project (DOST Project No. 9615).
- Natural and anthropogenic climate variability sgnals in a 237-year-long coral record from the PhilippinesInoue, Mayuri; Fukushima, A.; Chihara, M.; Genda, A.; Ikehara, Minoru; Okai, T.; Kawahata, Hodaka; Siringan, F. P.; Suzuki, Atsushi (American Geophysical Union, 2023-11-29)Both proxy and model studies conducted to understand anthropogenic warming have revealed historical variations in sea-surface temperature (SST) since the industrial revolution. However, because of discrepancies between observations and models in the late nineteenth century, the timing and degree of anthropogenic warming remain unclear. In this study, we reconstructed a 237-year-long record of SST and salinity using a coral core collected from Bicol, southern Luzon, Philippines, which is located at the northern edge of the western Pacific warm pool. The SST record showed volcanic cooling after several volcanic eruptions, including the 1815 Tambora eruption, but the pattern of change differed. Decadal SST variations at Bicol are connected to Pacific Decadal Variability (PDV). Therefore, it is suggested that the PDV conditions at the time of the eruption may have influenced marine conditions, such as the degree and duration of cooling and/or salinity, after the eruptions. Although there were discrepancies in SST variations among the modeled, observed, and proxy SST data from the late nineteenth to early twentieth centuries, SST data from the late twentieth century showed globally coherent anthropogenic warming, especially after 1976. In particular, summer SST in the northwestern Pacific has become more sensitive to anthropogenic forcing since 1976.