03. Science and Technology (Natural Sciences) Committee
Permanent URI for this communityhttps://repository.unesco.gov.ph/handle/123456789/3
In creating a culture of peace and addressing sustainable development challenges, UNESCO aims to cultivate the generation and application of scientific knowledge among its Member States. At UNACOM, we facilitate access to UNESCO’s international programmes in the sciences, such as the Intergovernmental Oceanographic Commission (IOC), Man and the Biosphere (MAB) Programme, and International Geoscience and Geoparks Programme (IGGP), among others.
Through this sector, the Commission aims to contribute to the following SDGs: 11 - Sustainable Cities and Communities, 13 - Climate Action, 14 - Life Below Water, and 15 - Life On Land. With the overarching vision of the 2023-2028 Philippine Development Plan (PDP), UNACOM targets grassroots-inspired cultural heritage and biodiversity protection and conservation, as well as multi-stakeholder partnerships for SDGs promotion.
Through this sector, the Commission aims to contribute to the following SDGs: 11 - Sustainable Cities and Communities, 13 - Climate Action, 14 - Life Below Water, and 15 - Life On Land. With the overarching vision of the 2023-2028 Philippine Development Plan (PDP), UNACOM targets grassroots-inspired cultural heritage and biodiversity protection and conservation, as well as multi-stakeholder partnerships for SDGs promotion.
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- Contrasting reproductive strategies between stress-tolerant and competitive coral taxaBonilla, K. G.; Guest, J. R.; Baria-Rodriguez, M. V. (Springer, 2023-04-19)Reproductive traits such as fecundity (i.e., the number of gametes produced) and the size and age of coral colonies at reproductive onset can vary in predictable ways among life history strategies. However, most studies on the onset of reproductive maturity in corals only report the presence or absence of oocytes with little known about variation in fecundity across size and age classes. This study aimed to determine the colony size and fecundity at the onset of reproductive maturity across size classes of two scleractinian corals with contrasting life history strategies, Acropora millepora (competitive) and Favites colemani (stress-tolerant). Colonies at a site in northwestern Philippines were sampled to determine the smallest colony size class with mature oocytes and to estimate fecundity across size classes. Histological slides were also prepared to verify the presence of mature gametes. Colonies were able to produce mature oocytes when they had attained colony diameters of 4.7 cm for A. millepora and 1.5 cm for F. colemani. A. millepora had lower fecundity, but larger oocytes compared to F. colemani. Although small colonies can contribute to the larval pool, the proportion of mature colonies increased for larger size classes, suggesting that larger colonies make a disproportionately greater contribution to population reproductive output. These findings contribute to our understanding of coral population dynamics, particularly in parameterizing population and demographic models for different coral life histories.
- Spatial variation in the benthic community structure of a coral reef system in the central Philippines: Highlighting hard coral, octocoral, and sponge assemblagesLalas, Jue Alef A.; Manzano, Geminne G.; Desabelle, Lee Arraby B.; Baria-Rodriguez, Maria Vanessa (Elsevier, 2023-07)Coral reefs are complex habitats that contain very high biodiversity and provide different ecosystem services. In the Coral Triangle, however, various major benthic components are still understudied. This can limit our understanding of coral reef community dynamics, especially in the presence of a changing climate coupled with local disturbances (e.g., decreased water quality). This study describes the benthic community structure of an ecologically and economically important coral reef system in the central Philippines through characterizing the assemblages of three major components (hard corals, octocorals, and sponges) among sites and stations with varying environmental conditions (i.e., exposure to monsoons, water quality levels). Results reveal significant variations in the mean percentage covers of hard corals, octocorals, and sponges at the site and station levels (ANOVA, p < 0.05), with hard corals dominating in Site 1, which is more exposed to the southwest monsoon, and Site 3, which is an embayed and unexposed site with low water quality, while soft corals dominated in Site 2, which is more exposed to the northeast monsoon. Multivariate analyses also revealed significant variations in the benthic community structure at different spatial scales (ANOSIM, p < 0.05). Interestingly, even stations within a site had significant variations in community structure, with different taxa being dominant. This study highlights the importance of conducting more detailed analyses of understudied taxa (i.e., octocorals and sponges) during coral reef surveys to improve our understanding of coral reef community dynamics that is very important for management.
- 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.
- Metabolic responses of the scleractinian coral Porites cylindrica Dana to water motion. I. Oxygen flux studiesRex, Augustus; Montebon, F.; Yap, Helen T. (Elsevier, 1995-03)Nubbins of Porites cylindrica Dana collected from a shallow reef flat in the northwestern Philippines were studied for water motion effects. Specimens were maintained in field and laboratory high (HWM) and low (LWM) water motion setups. The average maintenance times were 93 and 77 days for the field and laboratory study, respectively, which were carried out in tandem. After each maintenance period, oxygen fluxes of the corals were measured with increasing stirring rates in a laboratory flow-through respirometry system under a constant light intensity. Photosynthesis-irradiance (P-I) curves were also determined for the laboratory maintained nubbins as well as for a set of control nubbins which were kept in the collection site for 71 days. In both HWM and LWM corals, maximum rates of net photosynthesis (NP) and respiration (R) were achieved upon increasing stirring rates or turbulence to a certain level, indicating that the boundary layer limiting oxygen diffusion had been reduced to a minimum. The LWM corals attained maximum photosynthetic rates at lower rates of water motion, suggesting greater photosynthetic efficiency at lower levels of turbulence than their HWM counterparts. Profiles of NP and R with increasing stirring rates were consistently depressed for the LWM corals. Significant differences between the HWM and LWM treatments were detected in the NP profiles of the field maintained corals and in the R profiles of the laboratory maintained nubbins. The small yet significant difference in the NP profiles of the field HWM and LWM corals was attributed to the subsaturating irradiance used in the laboratory measurements because P-I curves of the laboratory maintained corals showed a large and significant difference between water motion treatments (HWM > LWM) at higher irradiances. While exhibiting lower photosynthetic rates, LWM corals had proportionally lower respiration rates resulting in P:R values very close to those of the HWM corals. Results suggest that Porites cylindrica is able to maintain its metabolic efficiency despite changes in the water motion regime.
- Effects of the soft coral Xenia puertogalerae on the recruitment of scleractinian coralsAtrigenio, M. P.; Aliño, P. M. (Elsevier, 1996-10)The effects of Xenia puertogalerae on the recruitment of juvenile corals was studied at two levels, involving early and more advanced settlement stages. Inhibition by X. puertogalerae was evident. Terracotta tiles established near soft coral colonies had fewer recruits than those located away from the soft corals. This inhibitory effect may be selective as acroporids were able to settle and survive in the presence of Xenia. This selectivity in allowing recruitment implies an important role for X. puertogalerae in determining succession and community structure. It may affect community structure by favouring the establishment of tolerant species, but effectively deters settlement of other corals in the area.
- Live slow, die old: larval propagation of slow-growing, stress-tolerant corals for reef restorationGuest, James; Baria-Rodriguez, Maria Vanessa; Toh, Tai Chong; dela Cruz, Dexter; Vicentuan, Kareen; Gomez, Edgardo; Villanueva, Ronald; Steinberg, Peter; Edwards, Alasdair (Springer, 2023-11-06)Efforts to restore coral reefs usually involve transplanting asexually propagated fast-growing corals. However, this approach can lead to outplanted populations with low genotypic diversity, composed of taxa susceptible to stressors such as marine heatwaves. Sexual coral propagation leads to greater genotypic diversity, and using slow-growing, stress-tolerant taxa may provide a longer-term return on restoration efforts due to higher outplant survival. However, there have been no reports to date detailing the full cycle of rearing stress-tolerant, slow-growing corals from eggs until sexual maturity. Here, we sexually propagated and transplanted two massive slow-growing coral species to examine long-term success as part of reef restoration efforts. Coral spat were settled on artificial substrates and reared in nurseries for approximately two years, before being outplanted and monitored for survivorship and growth for a further four years. More than half of initially settled substrates supported a living coral following nursery rearing, and survivorship was also high following outplantation with yields declining by just 10 to 14% over four years. At 6-years post-fertilisation over 90% of outplanted corals were reproductively mature, demonstrating the feasibility of restoring populations of sexually mature massive corals in under a decade. Although use of slower growing, stress tolerant corals for reef restoration may provide a longer-term return on investment due to high post-transplantation survival rates, considerable time is required to achieve even modest gains in coral cover due to their relatively slow rates of growth. This highlights the need to use a mix of species with a range of life-history traits in reef restoration and to improve survivorship of susceptible fast-growing taxa that can generate rapid increases in coral cover.
- 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.
- Survival and growth of coral recruits in varying group sizesLigson, Charlon A.; Cabaitan, Patrick C.; Harrison, Peter L. (Elsevier, 2022-11)Coral larvae usually settle as solitary individuals but sometimes also in aggregations, especially when settlement sites are limited. Fusion of coral individuals can consist of different group sizes with varying numbers of adjacent coral spat. However, little is known about the performance of coral individuals in different group sizes, especially during the early post-settlement phase, where high mortality usually occurs. Here, we investigated the performance of Acropora verweyi juveniles in varying group sizes of fused coral spat. Specifically, we examined the survival and growth rate of coral individuals, with four group size levels: solitary spat, 2, 3–5, 6–9, and 10–28-spat group size, over 21 weeks post-settlement. The highest survival was detected in the 6–9 spat group size followed by the 3–5 and 10–28 group sizes, with lower survival in the 2-spat group size and solitary spat. Overall, 7.4% of the 338 coral individuals reared in ex-situ hatchery conditions survived up to the last monitoring at 21 weeks. At 15 weeks post-settlement, the mean surface areas of solitary and 2-spat group sizes were five- to eight-fold smaller than in larger fused coral individuals. However, there were no significant differences between the percent growth changes among the coral group sizes. The present study suggests that fused coral spat of larger group sizes can immediately gain size, but not necessarily have higher growth rates within the first 15 weeks post-settlement. Results also revealed that fusions of at least six A. verweyi spat had higher survival than small fused individuals and solitary spat, at least in the first few months after settlement. The advantage of such fusions, especially in larger group sizes, may offer an enhanced survival for coral spat during the critical period of early post-settlement. This outcome provides potential advantages for coral restoration using sexual production of larvae.
- Genus and size-specific susceptibility of soft corals to 2020 bleaching event in the PhilippinesBaran, Christine; Luciano, Rhea Mae A.; Segumalian, Christine; Valino, Darryl Anthony; Baria-Rodriguez, Maria Vanessa (Taylor & Francis, 2023-05-08)Soft corals are zooxanthellate sessile animals supporting various organisms in coral reefs. However, their populations are threatened by the impacts of ocean warming. Under thermal stress conditions, soft corals may experience mild to severe bleaching which may lead to death. Understanding soft coral bleaching responses highlights the importance in predicting how populations and diversity may be affected by changing climate scenarios. In this study, we examined the bleaching responses of the three dominant soft coral genera (Lobophytum, n = 1318; Sarcophyton, n = 116; Sinularia, n = 639 colonies) in the Bolinao-Anda Reef Complex (BARC), Pangasinan, north-western Philippines during the 2020 thermal stress event in terms of genus and colony size susceptibility, and zooxanthellae density. Degree heating week (DHW) data from 1986–2020 were obtained using remotely sensed data to determine thermal anomalies in the study sites. The maximum DHW (6.3) in 2020 occurred between July–August while bleaching surveys were done during October of the same year. The percentage of bleached portions in each colony was used to determine bleaching category: no bleaching (0%), moderately bleached (1–50%) and heavily bleached (>50%). Quantification of bleaching prevalence and susceptibility of colony sizes were determined by colony count and mean diameter measurements taken from quadrat photographs in October 2020. Haphazard tissue collection (∼3 cm) in each colony of three soft coral genera per bleaching category was done to quantify zooxanthellae density. Results showed that Lobophytum colonies had the lowest bleaching prevalence (41%), followed by Sinularia (66%) and Sarcophyton (78%). All colony size classes of the three genera were susceptible to bleaching. However, smaller colonies of Lobophytum (<15 cm), Sarcophyton (<5 cm) and Sinularia (<5 cm) showed less susceptibility than large colonies. Zooxanthellae density was significantly reduced in moderately and heavily bleached colonies. The results of this study highlight that bleaching susceptibility is genus specific, with Sarcophyton and Sinularia being more susceptible to bleaching than Lobophytum. Smaller colonies seemed to be less susceptible to bleaching than large-sized soft corals suggesting a differential thermal stress response. Spatial variations in bleaching prevalence were also found among reef sites with varying environmental conditions and thermal stress histories. This work provided initial observations on how bleaching affects soft corals. Further studies on soft coral community recovery are recommended to fully understand how these organisms perform after thermal stress events.
- Reef location and season, but not recruitment substrate contour and composition, affect coral recruitment patternsdela Cruz, Dexter W.; Harrison, Peter L. (Elsevier, 2024)Most studies have quantified coral recruitment using recruitment tiles temporarily deployed on reefs. However, the wide range of tile types used in different studies potentially influences recruitment patterns thereby hindering accurate comparisons among reef areas. We examined the effect of different tile types with different surface structure and composition on spatial (reef locations) and temporal (season) patterns of coral recruitment in the northwestern Philippines. Dead coral skeleton, terracotta, and fibre-cement tiles were deployed and retrieved quarterly over a 15-month period. In contrast to previous studies, patterns of standardized density and composition of recruits were consistent among tile types. Recruits varied spatially and were highest in Caniogan reef, followed by Cory reef and Lucero reef, suggesting that coral recruitment in the Bolinao-Anda Reef Complex (BARC) is influenced by reef location and existing coral cover. Highest recruitment was also found during the peak coral spawning season. The results of this study contrast with some previous reports which indicate that coral recruitment patterns are strongly influenced by recruitment substrate types. Our study suggests that once sufficient biological conditioning of the tile surfaces has occurred, the microbial and algal community present on the different tile surfaces are similarly conducive to larval settlement of some coral taxa. © 2024 The Authors