National Committee on Marine Sciences (NCMS)
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- 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.
- Increased coral larval supply enhances recruitment for coral and fish habitat restorationHarrison, Peter L.; dela Cruz, Dexter W.; Cameron, Kerry A.; Cabaitan, Patrick C. (Frontiers Media SA, 2021-12-01)Loss of foundation reef-corals is eroding the viability of reef communities and ecosystem function in many regions globally. Coral populations are naturally resilient but when breeding corals decline, larval supply becomes limiting and natural recruitment is insufficient for maintaining or restoring depleted populations. Passive management approaches are important but in some regions they are proving inadequate for protecting reefs, therefore active additional intervention and effective coral restoration techniques are needed. Coral spawning events produce trillions of embryos that can be used for mass larval rearing and settlement on degraded but recoverable reef areas. We supplied 4.6 million Acropora tenuis larvae contained in fine mesh enclosures in situ on three degraded reef plots in the northwestern Philippines during a five day settlement period to initiate restoration. Initial mean larval settlement was very high (210.2 ± 86.4 spat per tile) on natural coral skeleton settlement tiles in the larval-enhanced plots, whereas no larvae settled on tiles in control plots. High mortality occurred during early post-settlement life stages as expected, however, juvenile coral survivorship stabilised once colonies had grown into visible-sized recruits on the reef by 10 months. Most recruits survived and grew rapidly, resulting in significantly increased rates of coral recruitment and density in larval-enhanced plots. After two years growth, mean colony size reached 11.1 ± 0.61 cm mean diameter, and colonies larger than 13 cm mean diameter were gravid and spawned, the fastest growth to reproductive size recorded for broadcast spawning corals. After three years, mean colony size reached 17 ± 1.7 cm mean diameter, with a mean density of 5.7 ± 1.25 colonies per m–2, and most colonies were sexually reproductive. Coral cover increased significantly in larval plots compared with control plots, primarily from A. tenuis recruitment and growth. Total production cost for each of the 220 colonies within the restored breeding population after three years was United States $17.80 per colony. A small but significant increase in fish abundance occurred in larval plots in 2018, with higher abundance of pomacentrids and corallivore chaetodontids coinciding with growth of A. tenuis colonies. In addition, innovative techniques for capturing coral spawn slicks and larval culture in pools in situ were successfully developed that can be scaled-up for mass production of larvae on reefs in future. These results confirm that enhancing larval supply significantly increases settlement and coral recruitment on reefs, enabling rapid re-establishment of breeding coral populations and enhancing fish abundance, even on degraded reef areas.We thank the Australian Centre for International Agricultural Research (ACIAR) for funding this research: grant ACIAR/FIS/2014/063 to PH, PC and J. Bennett. Thanks to ACIAR staff Chris Barlow, Ann Fleming, and Mai Alagcan for their ongoing support. Sincere thanks to the Galsim Family for use of Tanduyong Island as a field research base during the coral restoration fieldwork. We also thank staff and students at the Bolinao Marine Laboratory, Marine Science Institute, University of the Philippines, Diliman for their assistance with reef work: Elizabeth Gomez, Charlon Ligson, Rickdane Gomez and Fernando Castrence (including fish surveys), Marcos Ponce, Joey Cabasan, Sheldon Boco, Gabriel de Guzman, Albert Ponce, and Allan Abuan. We also thank Grant Cameron for field support and helping design, build and refine the prototype floating spawn catcher frames in 2016 and 2017.
- Juvenile scleractinian assemblage and its association with adults and benthos at shallow and upper mesophotic depths in fringing and atoll reefs in the PhilippinesAlbelda, Ritzelle L.; Cabaitan, Patrick C.; Sinniger, Frederic P.; Dumalagan, Edwin Jr; Quimpo, Timothy Joseph R.; Olavides, Ronald Dionnie D.; Munar, Jeffrey C.; Villanoy, Cesar L.; Siringan, Fernando (Elsevier B.V, 2020-10-15)The juvenile stage is a critical part of a scleractinian’s life history as it is when they are highly vulnerable to various post-settlement mortality processes, which influence the structure of adult scleractinian assemblages. Although numerous studies have been done to understand dynamics of juvenile assemblages at shallow water reefs (SWRs), similar studies on deeper and less explored reefs, such as mesophotic coral ecosystems (MCEs) remain limited. Using diver-based photo-quadrat method, we aimed to examine how juvenile scleractinian assemblages vary from SWRs (shallow: 3 to 10 m and middle: 10 to 20 m) to upper MCEs (deep: 30 to 40 m) in the fringing and atoll reefs in the Apo Reef Natural Park, Philippines. We also aimed to understand the potential association of juvenile scleractinian densities with adult scleractinian densities and benthic cover. A total of 12 families were recorded for both juveniles and adults with Poritidae being the most abundant, followed by Pocilloporidae and Acroporidae (and Merulinidae for juveniles only). Juvenile densities (ranging from 14 to 36 individuals/m2) varied among depth zone and reef type interactions and had a bimodal distribution, with the middle zone having the lowest density compared to the shallow and deep zones. Juvenile densities were correlated to benthic cover, particularly to high algal cover in the middle zone and availability of bare hard substrate in the shallow zone. Adult densities were also correlated with juvenile densities, but not commonly in the middle zone, emphasizing that it is only one of the many variables that contribute to juvenile assemblages. This study is the first to document juvenile scleractinian assemblages, how they vary from SWRs to MCEs in the Philippines and the Coral Triangle, and demonstrates the importance of benthos and adult brood stock in shaping juvenile scleractinian assemblages across depth zones.
- Variation in epibiont communities among restocked giant clam species (Cardiidae: Tridacninae) and across different habitat typesde Guzman, Ian Joseph A.; Cabaitan, Patrick C.; Hoeksema, Bert W.; Sayco, Sherry Lyn G.; Conaco, Cecilia (Springer, 2023-07-07)Giant clam shells provide a solid substrate for various species of epibionts. Yet, it is not well known how epibiont communities vary among populations of different giant clam species and in giant clams restocked in different habitat types. Here, we examined differences in the epibiont communities of three species of giant clams with different shell morphology (Tridacna gigas, Tridacna derasa, and Hippopus hippopus), and characterized the epibiont communities on T. gigas from three different habitat types (sandy reef flat, seagrass bed, and coral reef). Tridacna gigas had higher species richness, abundance, and cover of epibionts compared to the other two species. Tridacna gigas in coral reef habitat also displayed higher species richness and cover of sessile epibionts, while the same species in the sandy reef flat had higher species richness and abundance of mobile epibionts. Epibiont communities were more variable across habitat types than among different giant clam species restocked in a similar area. Differences in abundance of Trochus sp., Pyramidella sp., and crustose coralline algae contributed to the variability in epibiont communities among the giant clam species and across habitats. A few taxa were observed only on specific giant clam species and sites. For instance, Diadema sp. and Echinometra sp. were found only on T. gigas, and Diadema sp. was present only in the sandy reef flat. Both the complexity of the giant clam shells and habitat type contribute to differences in associated epibiont communities. This further emphasizes the ecological importance of giant clams as habitats for other invertebrates.The authors acknowledge Jun Castrence and the staff of Bolinao Marine Laboratory for assistance with field work. We also acknowledge the assistance of Edwin Dumalagan with coral and algae identification, Timothy Quimpo for his assistance and advice on statistical analysis, and Elizabeth Gomez for her assistance in generating the map of study sites. Lastly, we would like to thank members of the Coral Reef Ecology Laboratory (CoRE) for their helpful comments and suggestions on the study. 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 and CC (QMSR-MRRD-MEC-314-1542) and a Department of Science and Technology ASTHRDP Scholarship and University of the Philippines Marine Science Institute Thesis Writing Grant 2020 to ID. We thank the reviewers for the suggestions that helped improve our paper.
- Fish and benthic communities in an offshore and well-managed coral reef after bleaching disturbance in the PhilippinesQuimpo, Timothy Joseph R.; Requilme, Jeremiah Noelle; Gomez, Elizabeth; Sayco, Sherry Lyn; Dumalagan, Edwin E.; Siringan, Fernando P.; Conaco, Cecilia; Cabaitan, Patrick C. (Springer, 2023-08-29)Climate change is perhaps the greatest threat to coral reefs worldwide. However, there is spatial variation in the extent and severity of this disturbance, with offshore and well-managed reefs presumed to be less vulnerable to anthropogenic disturbance. Here, fish and benthic communities at the offshore and well-managed reefs of Apo Reef Natural Park, Philippines, were examined during a bleaching disturbance in 2016 and reassessed 2 (2018) and 3 years (2019) after using scuba surveys. Results showed that benthic communities varied more strongly with year attributed to changes in the benthic cover of coral. These changes were influenced by site, with some sites experiencing coral loss of 41–48%, while other sites exhibited minimal changes. Site differences in coral loss may be associated with coral cover, with sites that had high coral cover prior to bleaching incurring larger loss of coral cover. Fish communities varied more with sites and was associated with differences in the predominant benthos. The stability of fish communities with year despite coral loss may be attributed to the minimal loss of coral cover at some sites. For sites that experienced high losses of coral cover, the presence of alternative and deeper habitats may have provided shelter and food for more mobile fishes maintaining taxonomic composition within sites. This study shows that bleaching disturbance circumvents effective management, but impacts are variable even at small (≤ 3 km) spatial scales. Benthic community composition and presence of alternative habitats potentially alleviate the negative impacts of bleaching on reef fish diversity and abundance.We are grateful to the laboratory assistants F Castrence, R de Guzman, B Gabuay, R Valenzuela and K Adolfo for their assistance in the fieldwork. We thank the comments and criticisms of two anonymous reviewers that greatly improved the content of this manuscript.
- Microbial community structure and settlement induction capacity of marine biofilms developed under varied reef conditionsPadayhag, Blaire M.; Nada, Michael Angelou L.; Baquiran, Jake Ivan P.; Sison-Mangus, Marilou P.; San Diego-McGlone, Maria Lourdes; Cabaitan, Patrick C.; Conaco, Cecilia (Elsevier, 2023-08)Coral larval settlement relies on biogenic cues such as those elicited by microbial biofilm communities, a crucial element of coral recruitment. Eutrophication can modify these biofilm-associated communities, but studies on how this affects coral larval settlement are limited. In this study, we developed biofilm communities on glass slides at four sites with increasing distance from a mariculture zone. Biofilms farthest from the mariculture area were more effective at inducing the settlement of Acropora tenuis larvae. These biofilms were characterized by a greater proportion of crustose coralline algae (CCA) and gammaproteobacterial taxa compared to biofilms from sites closer to the mariculture zone, which had a greater proportion of cyanobacteria and no CCA. These findings suggest that nutrient enrichment due to mariculture activities alters the composition of biofilm-associated microbiome at nearby reef sites and indirectly causes poor coral larval settlement.