Distribution, habitat characteristics, and conservation status of Noah’s clam Tridacna noae (Röding, 1798) in the reefs of Palawan, Philippines
##plugins.themes.bootstrap3.article.sidebar##
Published
Jul 28, 2025
##plugins.themes.bootstrap3.article.main##
Niño Jess Mar F. Mecha
Abstract
This study aimed to provide an updated distribution range of Tridacna noae (Röding, 1798) in Palawan with notes on its habitat characteristics and conservation status. Data on the distribution and habitat characteristics were obtained from reef assessments from 2010-2023 and 10 Key Informants (KIs) and plotted using QGIS v3.28 software to illustrate its distribution in a map. A total of 12 reef sites within 8 municipalities in Palawan showed the presence of T. noae. Majority of these reefs were found in open-access coastal areas facing the West Philippine Sea. The clams were partially buried or settled on the top of dead or live coral in a depth of 1-5 meters from reef flat to reef slope surrounded by macroalgae. Tridacna noae remained unlisted in international, national, and local lists of protected species although it was confirmed in 2014 as a distinct species of giant clam, hence; the inclusion of T. noae in the lists of protected species in the Philippines is needed. Knowing the distribution, habitat characteristics, and conservation status of a certain threatened species such as the giant clam is an important step in managing and conserving wild population.
How to Cite
Mecha NJMF. 2025. Distribution, habitat characteristics, and conservation status of Noah’s clam Tridacna noae (Röding, 1798) in the reefs of Palawan, Philippines. The Palawan Scientist. 17(2):43–51. https://doi.org/10.69721/TPS.J.2025.17.2.05.
Downloads
Download data is not yet available.
##plugins.themes.bootstrap3.article.details##
Keywords
QGIS, remote sensing, teardrops giant clams,, hreatened species
References
Abesamis MR, Ang JL, Robles RC and Licuanan WY. 2023. Recovery of coral cover on inshore fringing reefs following mass coral bleaching in the Philippines. Coral Reefs, 42(1):99-104. https://doi.org/10.1007/s00338-022-02322-y
Ardines R, Mecha NJM and Dolorosa R. 2020. Commonly gleaned macro-benthic invertebrates in a small offshore island of Cawili, Cagayancillo, Palawan, Philippines. The Palawan Scientist, 12: 102–125. https://doi.org/10.69721/TPS.J.2019.11.1.09
ADB (Asian Development Bank). 2014. Regional state of the Coral Triangle—Coral Triangle marine resources: Their status, economies, and management. Mandaluyong City, Philippines: Asian Development Bank, 94pp.
Borsa P, Fauvelot C, Tiavouane J, Grulois D, Rio M, Naguit A, Andrefouet S and Wabnitz C. 2014. Distribution of Noah’s giant clam, Tridacna noae. Marine Biodiversity, 45: 339–344. https://doi.org/10.1007/s12526-014-0265-9
Borsa P, Fauvelot C, Andréfouët S, Chai TT, Kubo H and Liu LL. 2015. On the validity of Noah’s giant clam Tridacna noae (Röding, 1798) and its synonymy with Ningaloo giant clam Tridacna ningaloo Penny & Willan, 2014. Raffles Bulletin of Zoology, 63: 484–489.
Climaco RB, Aludia GM, Mecha NJMF, Cornel ARB, Acebuque ANAM, Rodriguez JF, Miguel JA, Menardo ID and Dolorosa RG. 2022. Status of coral reefs, butterflyfishes, and benthic macro-invertebrates in Araceli and Dumaran, Palawan, Philippines. The Palawan Scientist, 14(2): 54-64. https://doi.org/10.69721/TPS.J.2022.14.2.07
CITES (Conservation of International Trade of Endangered Species). 2024. Checklist of CITES Species. https://checklist.cites.org. Accessed on 20 January 2024.
Conales SF, Bundal NA and Dolorosa RG. 2015. High density of Tridacna crocea in exposed massive corals proximate the ranger station of Tubbataha Reefs Natural Park, Cagayancillo, Palawan, Philippines. The Palawan Scientist, 7: 36-39. https://doi.org/10.69721/TPS.J.2015.7.1.04
DA (Department of Agriculture). 2001. Conservation of rare, threatened and endangered fishery species. Philippines. Fisheries Administrative Order NO. 208, Series of 200. https://www.bfar.da.gov.ph/wp-content/uploads/2021/04/FAO-No.-208-s.-2001.pdf. Accessed on 24 January 2023.
Daño JC, Villanueva EG and Dolorosa RG. 2020. High density of Tridacna crocea in Rita Island, Puerto Princesa City, Palawan, Philippines. The Palawan Scientist, 12: 159-163. https://doi.org/10.69721/TPS.J.2020.12.1.11
Dolorosa RG, Climaco RB, Miguel JA, Aludia GM and Mecha NJ. 2023. Impact of super typhoon Odette on the reefs of northeastern Palawan, Philippines. Journal of Fisheries and Environment, 47(1):37-52.
Dolorosa RG, Mecha NJ, Bano JD, Ecube KM, Villanueva EG, Cabaitan PC. 2024. Declining population of giant clams (Cardiidae: Tridacninae) in Palawan, Philippines. Ocean and Coastal Research, 72: e24010. https://doi.org/10.1590/2675-2824072.22130
Dolorosa RG, Picardal RM, Conales SF. 2015. Bivalves and gastropods of Tubbataha Reefs Natural Park, Philippines. Check List, 11(1): 1506. http://dx.doi.org/10.15560/11.1.1506
Dumas P, Tiavouane J, Senia J, Willam A, Dick L and Fauvelot C 2014. Evidence of early chemotaxis contributing to active habitat selection by the sessile giant clam Tridacna maxima. Journal of Experimental Marine Biology and Ecology, 452: 63–69. https://doi.org/10.1016/j.jembe.2013.12.002
Ecube KMA, Villanueva EG, Dolorosa RG and Cabaitan PC. 2019. Notes on the first record of Tridacna noae (Röding, 1798) (Cardiidae: Tridacninae) in Palawan, Philippines. The Palawan Scientist, 11: 112-115. https://doi.org/10.69721/TPS.J.2019.11.1.09
Ellis SC. 1997. Spawning and early larval rearing of giant clams (Bivalvia: Tridacnidae) No. 130. Waimanalo, Hawaii: Center for Tropical and Subtropical Aquaculture, California, USA. 52pp.
Fartherree J. 2023. Giant Clams in the Reef Aquarium: Biology, Identification, and Care, Second Edition. Liquid Medium Publications, Tampa, Florida, USA. 196pp.
Fauvelot C, Zuccon D, Borsa P, Grulois D, Magalon H, Riquet F, Andréfouët S, Berumen ML, Sinclair-Taylor TH, Gélin P, Behivoke F, ter Poorten JJ, Strong EE and Bouchet P. 2020. Phylogeographical patterns and a cryptic species provide new insights into Western Indian Ocean giant clams phylogenetic relationships and colonization history. Journal of Biogeography, 47: 1086-1105. https://doi.org/10.1111/jbi.13797
Haworth BT, Cadigal GM, Zabala Jr. EC, Gonzales BJ, Jalover-Par CLS, Dolorosa RG, Gonzales-Plasus MM, Jontila JBS, Cabrestante Jr. MP, Bruce E and Baker E. 2024. Palawan (UNESCO Biosphere Reserve), Philippines: State of the Marine Environment 2024. Palawan Council for Sustainable Development Staff, Puerto Princesa City, Philippines. 130pp.
IUCN (International Union for Conservation of Nature). 2024. The IUCN Red List of Threatened Species. Version 2023-1. https://www.iucnredlist.org/. Accessed on 20 January 2024.
Johnson MS, Prince J, Brearley A, Rosser NL and Black R. 2016. Is Tridacna maxima (Bivalvia: Tridacnidae) at Ningaloo Reef, Western Australia? Molluscan Research, 36(4): 264-270. https://doi.org/10.1080/13235818.2016.1181141
Lee LK, Neo ML, Hii KS, Gu H, Chen CA, Lim PT and Leaw CP. 2024. Vanishing giants: An assessment on the population status of giant clams across Malaysia. Regional Studies in Marine Science, 74: 103546. https://doi.org/10.1016/j.rsma.2024.103546
Lizano AM and Santos MD. 2014. Updates on the status of giant clams Tridacna spp. and Hippopus hippopus in the Philippines using mitochondrial CO1 and 16S rRNA genes. Philippine Science Letters, 7: 187–200.
Marra-Biggs P, Fatherree J, Green A and Toonen R. 2022. Range Expansion and First Observation of Tridacna noae in American Sāmoa. Ecology and Evolution, 12: e9635. https://doi.org/10.1002/ece3.9635
Mecha NJMF. 2024. First record of Noah’s clam Tridacna noae (Röding, 1798) in Culion: An addition to the distribution range in Palawan, Philippines. The Palawan Scientist, 16(1): 81-84. https://doi.org/10.69721/TPS.J.2024.16.1.09
Mecha NJMF and Dolorosa RG. 2020. Searching the virtually extinct Tridacna gigas (Linnaeus, 1758) in the Reefs of Palawan, Philippines. The Philippine Journal of Fisheries 27(1): 1–18. https://doi.org/10.31398/tpjf/27.1.2019-0005
MFI (Malampaya Foundation Incorporated). 2020. First of the country's hatchery-grown Philippines’ true Tridacna gigas clams makes its home in north Palawan waters. https://www.malampayafoundation.org/news/first-of-the-countrys-hatchery-grown-philippines-true-tridacna-gigas-clams-makes-its-home-in-north-palawan-waters.Accessed on 24 January 2023.
Militz TA, Kinch J and Southgate PC. 2015. Population Demographics of Tridacna noae (Röding, 1798) in New Ireland, Papua New Guinea. Journal of Shellfish Research, 34(2): 329–335. https://doi.org/10.2983/035.034.0215
Morejohn K, Ainley L, Williamson J, Nevatte R, Liggins L, Cumbo VR and Gillings M. 2023. Genetic confirmation of Tridacna noae (Röding 1798) in the Cook Islands. Coral Reefs, 42(6): 1343–1350. https://doi.org/10.1007/s00338-023-02432-1
Neo ML. 2023. A Field Guide to Giant Clams of the Indo-Pacific. World Scientific Publishing Co. Pte. Ltd. Singapore. 201pp.
Neo ML, Eckman W, Vicentuan K, Teo SM and Todd PA. 2015. The ecological significance of giant clams in coral reef ecosystems. Biological Conservation, 181: 111–123. https://doi.org/10.1016/j.biocon.2014.11.004
Neo ML, Liu LL, Huang D and Soong K. 2018. Thriving populations with low genetic diversity in giant clam species, Tridacna maxima and Tridacna noae, at Dongsha Atoll, South China Sea. Regional Studies in Marine Science, 24: 278-287. https://doi.org/10.1016/j.rsma.2018.09.001
Neo ML and Low JKY. 2017. First observations of Tridacna noae (Röding, 1798) (Bivalvia: Heterodonta: Cardiidae) in Christmas Island (Indian Ocean). Marine Biodiversity, 48: 2183-2185. https://doi.org/10.1007/s12526-017-0678-3
PCSD (Palawan Council for Sustainable Development). 2017. PCSD Resolution No. 15-52. Approving the 2014 Updated List of Terrestrial and Marine Wildlife in Palawan and their Categories Pursuant to Republic Act 9147, Otherwise known as the Wildlife Resources Conservation and Protection Act of 2001. https://pcsd.gov.ph/pcsd-resolution-no-15-521/ Access on 20 January 2024.
Rosewater J. 1965. The family Tridacnidae in the Indo-Pacific. Indo-Pacific Mollusca, 1: 347–396.
Sandalo RM and Baltazar T. 1997. The Palawan biosphere reserve (Philippines). UNESCO (South Cooperation Program), Paris (France). Working Paper No. 19. 32pp.
Su Y, Hung JH, Kubo H, Liu LL. 2014. Tridacna noae (Röding, 1798) – A valid giant clam species separated from T. maxima (Röding, 1798) by morphological and genetic data. Raffles Bulletin of Zoology, 62: 124–135.
Triandiza T, Zamani NP, Madduppa H and Hernawan UE. 2019. Distribution and abundance of the giant clams (Cardiidae: Bivalvia) on Kei Islands, Maluku, Indonesia. Biodiversitas, 20(3): 884–892. https://doi.org/10.13057/biodiv/d200337
UNESCO (United Nations Educational, Scientific and Cultural Organization). 2021. Palawan (Philippines). World Network of Island and Coastal Biosphere Reserves.http://www.islandbiosphere.org/Contingut.aspx?IdPub=789. Accessed on 20 January 2024.
Vogel ML and Hoeksema BW. 2024. The role of aquaculture in the international trade of giant clams (Tridacninae) for the aquarium industry (2001–2019). Aquaculture, 583: 740563. https://doi.org/10.1016/j.aquaculture.2024.740563
Wabnitz CCC, Taylor ML, Green E and Razak T. 2003. From Ocean to Aquarium: The Global Trade in Marine Ornamental Species. UNEP-WCMC, Cambridge, UK. 64pp.
Ardines R, Mecha NJM and Dolorosa R. 2020. Commonly gleaned macro-benthic invertebrates in a small offshore island of Cawili, Cagayancillo, Palawan, Philippines. The Palawan Scientist, 12: 102–125. https://doi.org/10.69721/TPS.J.2019.11.1.09
ADB (Asian Development Bank). 2014. Regional state of the Coral Triangle—Coral Triangle marine resources: Their status, economies, and management. Mandaluyong City, Philippines: Asian Development Bank, 94pp.
Borsa P, Fauvelot C, Tiavouane J, Grulois D, Rio M, Naguit A, Andrefouet S and Wabnitz C. 2014. Distribution of Noah’s giant clam, Tridacna noae. Marine Biodiversity, 45: 339–344. https://doi.org/10.1007/s12526-014-0265-9
Borsa P, Fauvelot C, Andréfouët S, Chai TT, Kubo H and Liu LL. 2015. On the validity of Noah’s giant clam Tridacna noae (Röding, 1798) and its synonymy with Ningaloo giant clam Tridacna ningaloo Penny & Willan, 2014. Raffles Bulletin of Zoology, 63: 484–489.
Climaco RB, Aludia GM, Mecha NJMF, Cornel ARB, Acebuque ANAM, Rodriguez JF, Miguel JA, Menardo ID and Dolorosa RG. 2022. Status of coral reefs, butterflyfishes, and benthic macro-invertebrates in Araceli and Dumaran, Palawan, Philippines. The Palawan Scientist, 14(2): 54-64. https://doi.org/10.69721/TPS.J.2022.14.2.07
CITES (Conservation of International Trade of Endangered Species). 2024. Checklist of CITES Species. https://checklist.cites.org. Accessed on 20 January 2024.
Conales SF, Bundal NA and Dolorosa RG. 2015. High density of Tridacna crocea in exposed massive corals proximate the ranger station of Tubbataha Reefs Natural Park, Cagayancillo, Palawan, Philippines. The Palawan Scientist, 7: 36-39. https://doi.org/10.69721/TPS.J.2015.7.1.04
DA (Department of Agriculture). 2001. Conservation of rare, threatened and endangered fishery species. Philippines. Fisheries Administrative Order NO. 208, Series of 200. https://www.bfar.da.gov.ph/wp-content/uploads/2021/04/FAO-No.-208-s.-2001.pdf. Accessed on 24 January 2023.
Daño JC, Villanueva EG and Dolorosa RG. 2020. High density of Tridacna crocea in Rita Island, Puerto Princesa City, Palawan, Philippines. The Palawan Scientist, 12: 159-163. https://doi.org/10.69721/TPS.J.2020.12.1.11
Dolorosa RG, Climaco RB, Miguel JA, Aludia GM and Mecha NJ. 2023. Impact of super typhoon Odette on the reefs of northeastern Palawan, Philippines. Journal of Fisheries and Environment, 47(1):37-52.
Dolorosa RG, Mecha NJ, Bano JD, Ecube KM, Villanueva EG, Cabaitan PC. 2024. Declining population of giant clams (Cardiidae: Tridacninae) in Palawan, Philippines. Ocean and Coastal Research, 72: e24010. https://doi.org/10.1590/2675-2824072.22130
Dolorosa RG, Picardal RM, Conales SF. 2015. Bivalves and gastropods of Tubbataha Reefs Natural Park, Philippines. Check List, 11(1): 1506. http://dx.doi.org/10.15560/11.1.1506
Dumas P, Tiavouane J, Senia J, Willam A, Dick L and Fauvelot C 2014. Evidence of early chemotaxis contributing to active habitat selection by the sessile giant clam Tridacna maxima. Journal of Experimental Marine Biology and Ecology, 452: 63–69. https://doi.org/10.1016/j.jembe.2013.12.002
Ecube KMA, Villanueva EG, Dolorosa RG and Cabaitan PC. 2019. Notes on the first record of Tridacna noae (Röding, 1798) (Cardiidae: Tridacninae) in Palawan, Philippines. The Palawan Scientist, 11: 112-115. https://doi.org/10.69721/TPS.J.2019.11.1.09
Ellis SC. 1997. Spawning and early larval rearing of giant clams (Bivalvia: Tridacnidae) No. 130. Waimanalo, Hawaii: Center for Tropical and Subtropical Aquaculture, California, USA. 52pp.
Fartherree J. 2023. Giant Clams in the Reef Aquarium: Biology, Identification, and Care, Second Edition. Liquid Medium Publications, Tampa, Florida, USA. 196pp.
Fauvelot C, Zuccon D, Borsa P, Grulois D, Magalon H, Riquet F, Andréfouët S, Berumen ML, Sinclair-Taylor TH, Gélin P, Behivoke F, ter Poorten JJ, Strong EE and Bouchet P. 2020. Phylogeographical patterns and a cryptic species provide new insights into Western Indian Ocean giant clams phylogenetic relationships and colonization history. Journal of Biogeography, 47: 1086-1105. https://doi.org/10.1111/jbi.13797
Haworth BT, Cadigal GM, Zabala Jr. EC, Gonzales BJ, Jalover-Par CLS, Dolorosa RG, Gonzales-Plasus MM, Jontila JBS, Cabrestante Jr. MP, Bruce E and Baker E. 2024. Palawan (UNESCO Biosphere Reserve), Philippines: State of the Marine Environment 2024. Palawan Council for Sustainable Development Staff, Puerto Princesa City, Philippines. 130pp.
IUCN (International Union for Conservation of Nature). 2024. The IUCN Red List of Threatened Species. Version 2023-1. https://www.iucnredlist.org/. Accessed on 20 January 2024.
Johnson MS, Prince J, Brearley A, Rosser NL and Black R. 2016. Is Tridacna maxima (Bivalvia: Tridacnidae) at Ningaloo Reef, Western Australia? Molluscan Research, 36(4): 264-270. https://doi.org/10.1080/13235818.2016.1181141
Lee LK, Neo ML, Hii KS, Gu H, Chen CA, Lim PT and Leaw CP. 2024. Vanishing giants: An assessment on the population status of giant clams across Malaysia. Regional Studies in Marine Science, 74: 103546. https://doi.org/10.1016/j.rsma.2024.103546
Lizano AM and Santos MD. 2014. Updates on the status of giant clams Tridacna spp. and Hippopus hippopus in the Philippines using mitochondrial CO1 and 16S rRNA genes. Philippine Science Letters, 7: 187–200.
Marra-Biggs P, Fatherree J, Green A and Toonen R. 2022. Range Expansion and First Observation of Tridacna noae in American Sāmoa. Ecology and Evolution, 12: e9635. https://doi.org/10.1002/ece3.9635
Mecha NJMF. 2024. First record of Noah’s clam Tridacna noae (Röding, 1798) in Culion: An addition to the distribution range in Palawan, Philippines. The Palawan Scientist, 16(1): 81-84. https://doi.org/10.69721/TPS.J.2024.16.1.09
Mecha NJMF and Dolorosa RG. 2020. Searching the virtually extinct Tridacna gigas (Linnaeus, 1758) in the Reefs of Palawan, Philippines. The Philippine Journal of Fisheries 27(1): 1–18. https://doi.org/10.31398/tpjf/27.1.2019-0005
MFI (Malampaya Foundation Incorporated). 2020. First of the country's hatchery-grown Philippines’ true Tridacna gigas clams makes its home in north Palawan waters. https://www.malampayafoundation.org/news/first-of-the-countrys-hatchery-grown-philippines-true-tridacna-gigas-clams-makes-its-home-in-north-palawan-waters.Accessed on 24 January 2023.
Militz TA, Kinch J and Southgate PC. 2015. Population Demographics of Tridacna noae (Röding, 1798) in New Ireland, Papua New Guinea. Journal of Shellfish Research, 34(2): 329–335. https://doi.org/10.2983/035.034.0215
Morejohn K, Ainley L, Williamson J, Nevatte R, Liggins L, Cumbo VR and Gillings M. 2023. Genetic confirmation of Tridacna noae (Röding 1798) in the Cook Islands. Coral Reefs, 42(6): 1343–1350. https://doi.org/10.1007/s00338-023-02432-1
Neo ML. 2023. A Field Guide to Giant Clams of the Indo-Pacific. World Scientific Publishing Co. Pte. Ltd. Singapore. 201pp.
Neo ML, Eckman W, Vicentuan K, Teo SM and Todd PA. 2015. The ecological significance of giant clams in coral reef ecosystems. Biological Conservation, 181: 111–123. https://doi.org/10.1016/j.biocon.2014.11.004
Neo ML, Liu LL, Huang D and Soong K. 2018. Thriving populations with low genetic diversity in giant clam species, Tridacna maxima and Tridacna noae, at Dongsha Atoll, South China Sea. Regional Studies in Marine Science, 24: 278-287. https://doi.org/10.1016/j.rsma.2018.09.001
Neo ML and Low JKY. 2017. First observations of Tridacna noae (Röding, 1798) (Bivalvia: Heterodonta: Cardiidae) in Christmas Island (Indian Ocean). Marine Biodiversity, 48: 2183-2185. https://doi.org/10.1007/s12526-017-0678-3
PCSD (Palawan Council for Sustainable Development). 2017. PCSD Resolution No. 15-52. Approving the 2014 Updated List of Terrestrial and Marine Wildlife in Palawan and their Categories Pursuant to Republic Act 9147, Otherwise known as the Wildlife Resources Conservation and Protection Act of 2001. https://pcsd.gov.ph/pcsd-resolution-no-15-521/ Access on 20 January 2024.
Rosewater J. 1965. The family Tridacnidae in the Indo-Pacific. Indo-Pacific Mollusca, 1: 347–396.
Sandalo RM and Baltazar T. 1997. The Palawan biosphere reserve (Philippines). UNESCO (South Cooperation Program), Paris (France). Working Paper No. 19. 32pp.
Su Y, Hung JH, Kubo H, Liu LL. 2014. Tridacna noae (Röding, 1798) – A valid giant clam species separated from T. maxima (Röding, 1798) by morphological and genetic data. Raffles Bulletin of Zoology, 62: 124–135.
Triandiza T, Zamani NP, Madduppa H and Hernawan UE. 2019. Distribution and abundance of the giant clams (Cardiidae: Bivalvia) on Kei Islands, Maluku, Indonesia. Biodiversitas, 20(3): 884–892. https://doi.org/10.13057/biodiv/d200337
UNESCO (United Nations Educational, Scientific and Cultural Organization). 2021. Palawan (Philippines). World Network of Island and Coastal Biosphere Reserves.http://www.islandbiosphere.org/Contingut.aspx?IdPub=789. Accessed on 20 January 2024.
Vogel ML and Hoeksema BW. 2024. The role of aquaculture in the international trade of giant clams (Tridacninae) for the aquarium industry (2001–2019). Aquaculture, 583: 740563. https://doi.org/10.1016/j.aquaculture.2024.740563
Wabnitz CCC, Taylor ML, Green E and Razak T. 2003. From Ocean to Aquarium: The Global Trade in Marine Ornamental Species. UNEP-WCMC, Cambridge, UK. 64pp.
Section
Original Article
License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.