The First Record of Noah’s Giant Clam Tridacna noae (Röding, 1798) (Cardiidae: Tridacninae) with Notes on Population and Associated Giant Clam Species in Romblon, Philippines

This study reports the first confirmed record of Tridacna noae (Röding, 1798) in Carmen Bay, Romblon, Philippines, expanding the known distribution of the species within the region. Field surveys were conducted from January to March 2021 using modified belt transect methods across four sites, comprising both protected (sites 1 and 2) and non-protected areas (sites 3 and 4). A total of 171 giant clams, representing three species, were identified: Tridacna crocea (n = 140), T. maxima (n = 31), and T. noae (n = 10). Tridacna crocea was the most abundant species, while T. noae exhibited the lowest abundance. Both T. maxima and T. noae were restricted exclusively to marine protected areas. Population densities were markedly higher in protected sites (580 and 527 individuals per hectare) compared to non-protected areas (20 and 13 individuals per hectare), highlighting the critical role of marine protected areas in conserving tridacnid populations. The limited distribution and low population density of T. noae and T. maxima within the study area suggest that they are potentially vulnerable to anthropogenic pressures and habitat degradation. These findings provide essential baseline data on the occurrence, abundance, and spatial distribution of T. noae, underscoring the need for enhanced conservation strategies to safeguard giant clam biodiversity in the Philippines.