Journal Articles - UP - MSI
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- Acetic acid pretreatment in agar extraction of Philippine Gelidiella acerosa (Forsskaal) Feldmann et Hamel (Rhodophyta, Gelidiales)Roleda, M. Y.; Montaño, N. E.; Ganzon-Fortes, E. T.; Villanueva, R. D. (Walter de Gruyter GmbH, 1997)Application of different pre-extraction treatments and extraction methods were used to isolate agar from Gelidiella acerosa. Acetic acid pretreatment entailed soaking the sample in 0.5% acetic acid for 1 hour at 16-20 °C. Alkali pretreatment entailed treatment with l N NaOH at 90°C for 1 hour and eutralization in weak acid for another hour at 16-20 °C. Native agar was extracted directly from air dried samples. One hour extraction using steam pressure at 15-2PSI and boiling at 100 °C in a water bath were applied respectively. Comparative analysis showed that the acetic acid pretreated and autoclaved sample gave the highest agar yield (29.8 ± 2.41%) and gel strength (676 ± 4 g cm"2) among the extraction methods applied. Other physico-chemical properties of acid-modified agar were measured. Relative viscosity of a 1.0% solution at 65 °C ranged from 5-70 cps. A melting temperature of 90-98 °C is comparable to that of the agars from most Gelidiales, while a gelling temperature of 42-47 °C is relatively high which is suspected to be associated with a number of chemical variables masking or altering the basic structural unit of agar. Temperature hysteresis (difference between gelling and melting temperatures) at 48—50 °C was comparable to that of Difco Bacto agar tested at 50 °C.
- Low coral bleaching prevalence at the Bolinao-Anda Reef Complex, northwestern Philippines during the 2016 thermal stress eventQuimpo, Timothy Joseph R.; Requilme, Jeremiah Noelle C.; Gomez, Elizabeth J.; Sayco, Sherry Lyn G.; Tolentino, Mark Paulo S.; Cabaitan, Patrick C. (Elsevier BV, 2020-11)Here, we examined the coral bleaching responses during the 2016 thermal stress event and post-bleaching changes in coral communities in the heavily disturbed reefs of the Bolinao-Anda Reef Complex (BARC), northwestern Philippines. Less than 25% of colonies bleached, with 77% attributed to five genera (Dipsastrea, Porites, Fungia, Seriatopora, and Montipora). Coral bleaching prevalence was associated with site location, coral composition, and coral abundance, suggesting that small-scale variation (<20 km) in coral communities (taxa and density) influences spatial variation in coral bleaching prevalence. There was no noticeable change in coral composition and cover two years after the bleaching event as exposure to chronic disturbance likely selected for the dominance of stress tolerant coral taxa and communities. Results show that the 2016 thermal stress event caused coral bleaching but with low prevalence at the BARC, which suggests that disturbed reefs may provide spatial refuge to coral communities from thermal stress.We acknowledge M Ponce, F Castrence, R de Guzman, G de Guzman, R Adolfo, and R Uriarte for the field assistance; and boatmen and administration from the Bolinao Marine Laboratory of the UPMSI (University of the Philippines Marine Science Institute) for their valuable assistance in the logistics and field works. We are grateful to R Dizon for kindly reading and providing suggestions that improved the manuscript. This study was funded by the OVCRD (Office of the Vice Chancellor for Research and Development) Outright Research Grant (Project No. 161607 PNSE) and the Marine Science Institue In-house Research Grant of the University of the Philippines; and grants from the Philippine Council for Agriculture, Aquatic, and Natural Resources Research and Development of the Department of Science and Technology (QMSR-MRRD-MEC-295-1449 and QMSR-MRRD-MEC314-1542) of PC Cabaitan.
- Feasibility of early outplanting of sexually propagated Acropora verweyi for coral reef restoration demonstrated in the PhilippinesLigson, Charlon A.; Tabalanza, Tracy D.; Villanueva, Ronald D.; Cabaitan, Patrick C. (Wiley, 2019-11-20)Over the last 20 years, coral sexual propagation techniques for reef restoration have been steadily developed and improved. However, these techniques involve considerable time and costs to grow coral propagules. There is a need to examine the optimal size of juvenile corals for outplantation. Here, we outplanted sexually propagated small (3–5 mm diameter) and large (10–15 mm diameter) Acropora verweyi corals at 4 months after fertilization at two sites in northwestern Philippines, and compared their survival and radial growth rate after a year. A. verweyi coral juveniles (n = 240) exhibited an overall mean survival of 29.5% and growth rate of 11.12 ± 6.2 mm/year (mean ± SD). Large colonies had a significantly higher growth rate than smaller colonies. Although survivorship of large juveniles was significantly better than that of the smaller ones at one site, it did not differ significantly at the other. Each 4-month-old coral cost US$1.52 to produce, while the cost of each of the outplanted juveniles (n = 240) was about US$2.67, whereas the cost of each survivor about a year after outplantation was US$11.47. Results suggest that A. verweyi reared in ex situ nurseries for only 4 months can survive reasonably well when outplanted onto coral reefs.
- Predicting fish kills and toxic blooms in an intensive mariculture site in the Philippines using a machine learning modelYñiguez, Aletta T.; Ottong, Zheina J. (Elsevier BV, 2020-03)Harmful algal blooms (HABs) that produce toxins and those that lead to fish kills are global problems that appear to be increasing in frequency and expanding in area. One way to help mitigate their impacts on people's health and livelihoods is to develop early-warning systems. Models to predict and manage HABs typically make use of complex multi-model structures incorporating satellite imagery and frequent monitoring data with different levels of detail into hydrodynamic models. These relatively more sophisticated methods are not necessarily applicable in countries like the Philippines. Empirical statistical models can be simpler alternatives that have also been successful for HAB forecasting of toxic blooms. Here, we present the use of the random forest, a machine learning algorithm, to develop an early-warning system for the prediction of two different types of HABs: fish kill and toxic bloom occurrences in Bolinao-Anda, Philippines, using data that can be obtained from in situ sensors. This site features intensive and extensive mariculture activities, as well as a long history of HABs. Data on temperature, salinity, dissolved oxygen, pH and chlorophyll from 2015 to 2017 were analyzed together with shellfish ban and fish kill occurrences. The random forest algorithm performed well: the fish kill and toxic bloom models were 96.1% and 97.8% accurate in predicting fish kill and shellfish ban occurrences, respectively. For both models, the most important predictive variable was a decrease in dissolved oxygen. Fish kills were more likely during higher salinity and temperature levels, whereas the toxic blooms occurred more at relatively lower salinity and higher chlorophyll conditions. This demonstrates a step towards integrating information from data that can be obtained through real-time sensors into a an early-warning system for two different types of HABs. Further testing of these models through times and different areas are recommended.
- Changes in community structure and biomass of seagrass communities along gradients of siltation in SE AsiaTerrados, J.; Duarte, C. M.; Fortes, M. D.; Borum, J.; Agawin, N.; Bach, S.; Thampanya, U.; Kamp-Nielsen, L.; Kenworthy, W. J.; Geertz-Hansen, O.; Vermaat, J. (Elsevier BV, 1998-05)The patterns of change in species richness and biomass of Southeast Asian seagrass communities along siltation gradients were compared at different sites in The Philippines and Thailand. Seagrass species richness and community leaf biomass declined sharply when the silt and clay content of the sediment exceeded 15%. Syringodium isoetifolium and Cymodocea rotundata were present only in multispecific meadows, while Enhalus acoroides was the only species remaining in heavily silted sediments. The following ranking of species sensitivity to siltation is proposed (from the least to most sensitive): S. isoetifolium→C. rotundata→Thalassia hemprichii→Cymodocea serrulata→Halodule uninervis→Halophila ovalis→Enhalus acoroides. Positive correlations were found between species richness and both community leaf biomass and the leaf biomass of individual seagrass species. The increase in community biomass with increasing species richness was associated with a more even distribution of the leaf biomass among seagrass species. The relationships between percent silt and clay in the sediment and seagrass community leaf biomass and species richness provide useful dose–response relationships which can be used to set allowable or threshold siltation loads in SE Asian coastal waters, and indicate that species loss from seagrass meadows is an early warning of detrimental siltation loads.
- MPA-FishMApp – a citizen science app that simplifies monitoring of coral reef fish density and biomass in marine protected areasAbesamis, Rene; Balingit, Rodel; de Castro, Romulo; Aguila, Raphael Nelo; Cabiguin, Maryjune; Villagracia, Julius; Susmeña, Marynoll; Montemar, Mario Neil; Yocor, Antonio (National Fisheries Research and Development Institute, 2022-12)Monitoring changes in fish density and biomass inside marine protected areas (MPAs) through fish visual census (FVC) can determine if MPAs are achieving their goal of promoting fish population recovery. Simplified FVC methods have been developed for citizen scientists to enable them to monitor fish populations in MPAs. However, MPA monitoring programs led by local stakeholders remain rare and difficult to sustain due to technical barriers related to FVC data management. Here, we describe and evaluate a novel online app called MPA-FishMApp, which we developed to help stakeholders of MPAs that protect coral reefs in the Philippines efficiently store, analyze, and visualize FVC data. MPA-FishMApp is coupled to a simplified FVC method wherein the observer records only 21 reef fish species groups during surveys. The app provides a simple data entry interface, cloud storage, and algorithms to estimate fish density and biomass. Spatial and temporal trends in fish density and biomass can be instantaneously visualized in the app based on relative importance to fisheries. Field testing suggested that the MPA-FishMApp methodology (simplified FVC and app) is sensitive enough to detect qualitative patterns showing differences in density and biomass that may develop between MPAs and fished sites, especially in fishes that are highly important to fisheries. However, users must have sufficient training and experience in simplified FVC to produce reliable data. MPA-FishMApp may help reverse the lack of monitoring in MPAs across the Philippines and offers an accessible, transparent, and auditable venue for collaboration between citizen scientists and professional scientists.
- C30 — A simple, rapid, scientifically valid, and low-cost method for citizen-scientists to monitor coral reefsLicuanan, Wilfredo Y.; Mordeno, Princess Zyrlyn B.; Go, Marco V. (Elsevier, 2021-09)The extent and speed of recent changes in reef coral abundances due to ocean warming and human impacts require more widespread capability to map and measure these changes, especially in countries like the Philippines. We present “C30”, a simple, rapid, scientifically valid, and low-cost method for skin divers or freedivers to take random photo-quadrat images within predefined stations on the upper reef slope. C30 yields coral cover data similar to those collected using the more intensive C5 method and can be as powerful in detecting small differences in reef cover. Less time is also needed for training personnel and sampling. However, more photo-quadrat images, better cameras, and closer collaboration with local scientists are required if higher precision data and estimates of coral diversity are needed from C30. C30 is a valuable tool for participatory, community-based citizen science monitoring of coral reefs.We thank the Department of Science and TechnologyPhilippine Council for Agriculture, Aquatic and Natural Resources Research and Development (QMSR-MRRD-COR-0-1209 and PCAARRD-GIA 4478), and the Department of Environment and Natural Resources Coral Reef Visualization and Assessment, The Philippines Project for funding some of the fieldwork. The initial research on citizen-science monitoring was undertaken with funding from Oscar M. Lopez Center for Climate Change Adaptation and Disaster Risk Management Foundation, Inc., The Philippines (Grant number OMLC RG 2017-18). We also thank the DLSU Innovation and Technology Office for the patent application for the C30 monopod in the Intellectual Property Office of the Philippines. The comments and suggestions of the reviewers are acknowledged and are very much appreciated. WY Licuanan is the holder of the Br H Alfred Shields FSC Professorial Chair in Biology and Br Cresentius Richard Duerr FSC Professorial Chair in Biochemistry.
- Insights into the environmental conditions contributing to variability in the larval recruitment of the tropical sardine Sardinella lemuruPata, Patrick R.; Yñiguez, Aletta T.; Deauna, Josephine Dianne L.; De Guzman, Asuncion B.; Jimenez, Cesaria R.; Rosario, Roselle T. Borja-Del; Villanoy, Cesar L. (Elsevier, 2021-07)The small pelagic fishery in the southern Philippines is one of the largest contributors to fisheries production in the country, and is dominated by the Bali sardine Sardinella lemuru. This species is a year-round spawner that has its peak spawning period during the northeast monsoon (NEM) months of November to February. However, there is still limited information on the conditions that affect this species’ survival during its early life history stages. Here, we attempt to discern the importance of temperature, prey density and advection on sardine larvae. The larvae were represented as passive particles that were released in known spawning grounds to simulate dispersal. The conditions the larvae experienced, namely, temperature and estimated prey density based on satellite chlorophyll-a values were recorded at each time step until the estimated recruitment age of 60 days. The temporal and spatial averaged conditions of recruited sardines showed that sardines spawned during the NEM months experienced higher chlorophyll-a, lower (more optimal) sea surface temperature, albeit higher advective loss, than sardines spawned during other months. Comparisons between years showed that during higher reported catch years, sardine larvae experienced lower temperatures and higher retention nearshore. Our results emphasize that sardine stock management efforts need to recognize the contribution of the temporally variable sardine environment to patterns in sardine recruitment and consequently in catches.The authors would like to thank Dr. Wilfredo Campos, Luke Felix, Dr. Rio Naguit, Denmark Recamara, and the Research for Sardines Volunteer Program (RSVP) volunteers for sharing sardine fisheries data; Arjay Cayetano for helping start the model used; and Iris Salud Bollozos for useful insights on larval ecology. This study was fully funded by the Department of Science and Technology–Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (DOSTPCAARRD) under the program, “Development of robust tools for managing sardine fisheries in the Philippines: Zamboanga Upwelling Bohol Sea System Program.” The authors declare no conflict of interest.
- Ammonium and phosphate excretion in three common echinoderms from Philippine coral reefsDy, Danilo T.; Yap, Helen T. (Elsevier BV, 2000-08)The ammonium and phosphate excretion and oxygen consumption of three species of echinoderms (Tripneustes gratilla, Protoreaster nodosus and Ophiorachna incrassata) commonly encountered in Philippine coral reefs were investigated in relation to time of day (i.e. daytime between 10:00 and 12:00 h vs. nighttime between 22:00 and 24:00 h) and their recent feeding history (i.e. recently-collected vs. short-term starvation for 3±1 days). The experiment used whole organism incubations and followed a nested hierarchical design. Ammonium excretion rates were 1447±310 nmol g−1 DW h−1 (mean±S.E., n=24) for T. gratilla, 361±33 for O. incrassata and 492±38 for P. nodosus. Ammonium excretion differed significantly among species, time of incubation and recent feeding history. Interaction between species and recent feeding history was also significant. The organisms excreted more ammonium during daytime except for starved specimens of O. incrassata. In addition, animals that were starved in the laboratory for a few days had a tendency to excrete more ammonium than recently-collected specimens. Phosphate excretion rates were 25±13 nmol g−1 DW h−1 for T. gratilla, 10±2 for O. incrassata and 4±1 for P. nodosus. There were no significant differences in phosphate excretion among the three species of echinoderms, their recent feeding history and time of day. Oxygen consumption rates were 286±24 μg O2 g−1 DW h−1 for T. gratilla, 64±3 for O. incrassata and 54±3 for P. nodosus. Oxygen consumption differed significantly among species and recent feeding history but differed only slightly with time of incubation. There was a significant correlation between oxygen consumption and ammonium excretion (r=0.48, P=0.018), and between oxygen consumption and phosphate excretion (r=0.41, P=0.047) for T. gratilla. The nutrient excretion by tropical echinoderms is another pathway by which inorganic nutrients are regenerated in coral reef communities. However, the quantity of nutrients excreted is dependent on the species of echinoderms, their nutritional status and time of day.
- Seasonal variations in the yield, gelling properties, and chemical composition of agars from Gracilaria eucheumoides and Gelidiella acerosa (Rhodophyta) from the PhilippinesVillanueva, R. D.; Montaño, N. E.; Romero, J. B.; Aliganga, A. K. A.; Enriquez, E. P. (Walter de Gruyter GmbH, 1999-01-01)The yield, physical, and chemical properties of agars from two Philippine red seaweeds, Gracilaria eucheumoides and Gelidiella acerosa, were investigated on a bimonthly basis. The yield of agar from Gracilaria eucheumoides was at a maximum during the early rainy season (May, 29%) and at a minimum during the summer month of March (20%). In Gelidiella acerosa, a peak in agar yield was also recorded in May (21%), with generally higher yields recorded during the rainy than in the dry season. Agar gel strengths fluctuated from 225 to 430 g cm−2 and from 160 to 820 g cm−2 for Gracilaria eucheumoides and Gelidiella acerosa, respectively, and both agars exhibited strongest gels in July. Significant seasonal variations were observed in the gelling and melting temperatures of agar from Gracilaria eucheumoides, but not from Gelidiella acerosa. Sulphate content only varied slightly in agar samples from Gracilaria eucheumoides, while a higher sulphate content was found in Gelidiella acerosa agar during the dry season. Moreover, the sulphate content in G. acerosa agar fluctuated inversely with the 3,6-anhydrogalactose content. A FT-IR analysis showed a fairly constant spectrum for temporal Gracilaria eucheumoides agar while peaks attributed to S–O vibrations intensified in Gelidiella acerosa samples which were recorded to contain high sulphate residues and possess low gel strengths. Diagnosis of the FT-IR spectra in the 1000–400 cm−1 frequency range was also conducted in comparison with agarose and Gracilaria chilensis agar.