Morphometric Variation, Growth Patterns, and Interpopulation Comparisons of Thalamita crenata (Rüppell, 1830) in Surigao del Norte and Agusan del Norte, Philippines

Thalamita crenata is a commercially and ecologically important crab species, yet comprehensive biological data on its populations in the Philippines remain limited. This study aimed to provide an initial assessment of T. crenata populations in Surigao City, Surigao del Norte and Buenavista, Agusan del Norte, Philippines. A total of 104 individuals were sampled and measured at each site. The maturity of the collected individuals was inferred from the mean values of their morphometric indices and the presence of ovigerous females. Descriptive comparisons of morphometric values between the two sites suggested potential variations in growth conditions. Mann-Whitney U tests revealed significant differences in cheliped dactylus length (CDL) between the two populations, with individuals from Buenavista exhibiting larger chelipeds (males: U = 387.5, z = 4.38, p < 0.0001; females: U = 639, z = -6.11, p < 0.0001). Strong positive Pearson’s r correlations between carapace dimensions (width and length) and body weight were observed in both areas (Surigao City: r = 0.677-0.695; Buenavista: r = 0.923-0.834) highlighting the utility of carapace size measurements for monitoring growth patterns. These findings provide valuable baseline data for future assessments of mangrove health, fisheries production, and environmental suitability for T. crenata. Future investigations should examine environmental factors influencing growth variations and assess potential threats to these populations. Such efforts will be crucial for developing effective strategies for more proactive environmental management among related marine ecosystems.