National Committee on Marine Sciences (NCMS)
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- Spatial and short-term temporal patterns of octocoral assemblages in the West Philippine SeaLalas, Jue Alef A.; Lim, Romina Therese S.; Cabasan, Joey P.; Segumalian, Christine S.; Luciano, Rhea Mae A.; Valino, Darryl Anthony M.; Jacinto, Melchor R.; Arceo, Hazel O.; Baria-Rodriguez, Maria Vanessa (Frontiers Media SA, 2022-01-06)Octocorals are relatively understudied than other coral reef organisms despite their ecological and economic values. The Philippines is known to have high marine biodiversity, but information on octocorals is lacking. This study investigated spatial and temporal variations in the assemblage of octocorals in selected reef sites in the West Philippine Sea (WPS)- the Kalayaan Island Group (i.e., Pag-asa, Sabina, Lawak, and Northeast Investigator) and Ulugan in 2017 and 2019. Results showed high octocoral taxonomic richness (at least 10 families) in the study sites. Mean percent octocoral cover in WPS was 5.35% SE ± 0.55, with Sabina having the highest octocoral cover in both years. Significant differences in octocoral cover were observed among sites in both years, but among-station differences were only observed in 2017. Octocoral assemblage also differed among sites in both years (ANOSIM: R > 0.5, p < 0.05), wherein different octocoral taxa dominated in different sites. In particular, variations were driven by high cover of holaxonians, nephtheids, and coelogorgiids in Sabina, and clavulariids, tubiporiids, and xeniids in Northeast Investigator in 2017. In 2019, significant variations were driven by high cover of helioporiids in Pag-asa, while Sabina had higher abundance of holaxonians, nephtheids, alcyoniids, and xeniids. Short-term temporal variation on octocoral cover in monitoring stations in Pag-asa was not observed (Kruskal-Wallis, p > 0.05), although the overall mean octocoral cover increased from 1.23% ± SE 0.47 in 2017 to 2.09% SE ± 0.37 in 2019. Further, there was no significant change in the octocoral assemblage in Pag-asa between years (ANOSIM, R = 0.11, p = 0.07). This study highlights high octocoral taxonomic richness in the WPS relative to other sites in the Indo-Pacific Region and provides baseline information on the octocoral assemblages, which can be useful for future ecological studies and marine biodiversity conservation efforts.We would like to thank the Department of Agriculture-Bureau of Fisheries and Aquatic Resources (DA-BFAR), Philippine Coast Guard (PCG), the Municipality of Kalayaan, and the Philippine Navy for their assistance and support during the research expeditions in the West Philippine Sea. We also thank Lovely Joy Heyres for assisting in the field collection and image analysis, and Kevin Yatco and Socorro Rodrigo for assisting in the satellite product processing. We also thank the valuable insights and suggestions given by the editor and reviewers of this journal that helped improve this manuscript.
- Survival and sexual maturity of sexually propagated Acropora verweyi corals 4 years after outplantationLigson, Charlon A.; Cabaitan, Patrick C. (Wiley, 2021-04-19)Most coral reef restoration efforts are carried out over 1–2 years, and few have assessed long-term (over 3 years) outcomes. Although studies of outplantation of sexually propagated corals have reported promising initial results, few studies have followed outplanted corals to maturity. Here, we monitored sexually propagated Acropora verweyi corals for 4 years post-outplantation to determine their survival and sexual maturity. These corals were outplanted when 4 months old in two size classes (small = 0.3–0.5 cm; large = 1.0–1.5 cm) at two sites in the northwestern Philippines. Four years after outplantation, the 240 colonies of A. verweyi exhibited 17.9% survival, with mean diameters ranging from 7.48–26.8 cm. Most of the surviving outplants were gravid (81.4% of the 43 colonies) with mean diameters of at least 11.8 cm. Higher survivorship was detected in the initial large size class outplants than in the small ones at the natal site, but not at the other site. However, 4 years after outplantation, there was no significant difference in terms of geometric mean diameter between the initial size classes or between the sites. Results show that 4-month-old outplants of sexually propagated corals can survive until sexual maturity and are already capable of contributing gametes for the potential recovery of degraded coral communities at age 4 years.The authors are grateful to Ronald de Guzman, Francis Kenith Adolfo,and Renato Adolfo for the field and hatchery assistance.This study was supported by a grant from the Philippine Council for Agriculture, Aquatic, and Natural Resources Research and Development of the Department of Science and Technology to PCC. The authors are also grateful to Prof. Peter Harrison for providing CAL a research assistantship opportunity and for additional logistical support through an Philippine Council for Agriculture, Aquatic, and Natural Resources Research and Development.
- Zooxanthellae diversity and coral-symbiont associations in the Philippine archipelago: specificity and adaptability across thermal gradientsTorres, Andrew F.; Valino, Darryl Anthony M.; Ravago-Gotanco, Rachel (Frontiers Media SA, 2021-10-20)Prolonged thermal stress and high levels of solar irradiance can disrupt the coral-algal symbiosis and cause bleaching and lowered overall fitness that lead to the likely death of the cnidarian host. Adaptive bleaching and acclimatization of corals, which posits bleaching as an opportunity for the coral host to switch its currently susceptible endosymbionts to more stress-tolerant taxa, offers hope for survival of reefs amid rapidly warming oceans. In this study, we explored the diversity and distribution of coral-zooxanthellae associations in the context of geospatial patterns of sea surface temperature (SST) and thermal anomalies across the Philippine archipelago. Thermal clusters based on annual sea surface temperature means and each site’s frequency of exposure to heat stress were described using three-decade (1985–2018) remotely sensed data. Haphazard sampling of 628 coral fragments was conducted in 14 reef sites over 3 years (2015–2018). Using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) fingerprinting and sequencing of the zooxanthellae ITS2 region, we characterized endosymbiont diversity within four reef-building coral families across archipelagic thermal regimes. Consistency in dominant Symbiodiniaceae taxon was observed in Acropora spp., Porites spp., and Heliopora coerulea. In contrast, the family Pocilloporidae (Pocillopora spp., Seriatopora spp., and Stylophora pistillata) exhibited biogeographic variability in zooxanthellae composition, concordant with inferred occurrences of sustained thermal stress. Multivariate analyses identify two broad Pocilloporidae clusters that correspond with mean SST ranges and frequency of exposure to bleaching-level thermal stress which are largely supported by ANOSIM. Differences in zooxanthellae assemblages may reflect host-specific responses to ecological or environmental gradients across biogeographic regions. Such patterns of variability provide insight and support for the adaptability and potential resilience of coral communities in geographically and oceanographically complex regions, especially amidst the increasing severity of global and local-scale stressors.This paper is dedicated to the late Ronald D. Villanueva whose contribution to the project during its inception has been invaluable. The authors thank Patrick R. Pata and the reviewers LE and RC-T for their helpful comments and suggestions, and acknowledge Hazel O. Arceo, Cesar L. Villanoy, and Maria Lourdes San Diego-McGlone for their support of this study. Eileen Peñaflor and Mariana Soppa shared key knowledge in processing satellite products. Mikhael Tañedo, Romer Albino, Emmeline Jamodiong, David Siquioco, Lovely Heyres, Rhea Luciano, Joey Cabasan, Frederico Sabban, Geminne Manzano, Clairecynth Yu, Joyce Velos, Joseph Garcia, Robert Casauay, Maryjune Cabiguin, Macy A onuevo-Arcega, Ariel Loja, Jerome Genilan, Amabelle Go, Jamie Dichaves, Elaine Saniel, and Miledel Quibilan assisted with field collections. Supporting hard coral data were provided by the DOST-PCAARRD NACRE Program and the DENR-BMB WPS and SECURE Philippine Rise Projects. This is MSI contribution number 486.
- Reproductive biology and early life history of the solitary coral Heliofungia actiniformis from Singapore and the PhilippinesSayco, Sherry Lyn G; Prasetia, Rian; Todd, Peter A.; Loya, Yossi; Valencia, Brian; Calle, Lala Grace; Cabaitan, Patrick C. (Springer, 2024-01-13)Reproduction and early life history are central to understanding the biology and ecology of organisms, however such information is limited for solitary corals. Here, we compared the reproductive traits of the solitary coral Heliofungia actiniformis from different latitudinal locations (Singapore, 1°N and the Philippines, 16°N) and examined their early life development, settlement competency, and juvenile growth and survival. A total of 32 corals from Pulau Hantu reefs in Singapore and 102 corals from Bolinao and Anda reefs in the Philippines were studied between 2019 and 2022. Heliofungia actiniformis broadcasts spawned gametes during several nights, generally between 22:00 and 01:00, before and after full moon, from February to May in Singapore and from March to June in the Philippines. Spawning within a month occurred for up to 16 nights in Singapore and 10 nights in the Philippines. Sex change in two individuals between years was observed in the Philippines. The average egg size was smaller in Singapore than that in the Philippines. We determined that eggs were fertilized within 2 h after sperm addition, and developed into swimming larvae within 64 h, which began to settle after 24 h. Larval survival after three mo of culture was 1.72 ± 1.0% and juvenile diameter ranged from 0.33 to 1.30 mm. Asexual buds were first observed in 15 mo old juveniles that were at least 8 mm in diameter. 24 mo old juveniles were observed to detach from their stalk and the empty stalk regenerated polyps. Our results highlight the latitudinal variability in the reproductive traits of solitary corals, serve as a baseline for their early life history, and advance our understanding of their population dynamics.
- 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.We are grateful to Christine Baran, Jue Alef Lalas, Jerry Arboleda, Gabriel de Guzman, the students and research assistants of Community and Ecology and Interactions of Marine Bionts and Benthic Ecosystems Laboratories for their valuable assistance during field and laboratory works, Darryl Valino for the site map, and Liam Lachs for the assistance on the statistical analyses. This research was supported by the University of the Philippines Marine Science Institute’s In-house project, Department of Science and Technology – ASTHRDP Thesis Grant, and University of the Philippines – Office of the Vice President for Academic Affairs’ Balik Ph.D. project (OVPAA-BPhD-2018-02).
- 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.
- 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.
- 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.
- 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.We acknowledge the Bolinao Marine Laboratory of the University of the Philippines for logistics and fieldwork assistance. Thanks to Kevin Yatco and Socorro Rodrigo for providing technical assistance in obtaining remotely sensed temperature data. Thank to Kevin Yatco and Socorro Rodrigo, and Kevin Labrador for providing technical assistance in obtaining remotely sensed temperature data and assistance in statistical analysis, respectively.