Declining population of giant clams (Cardiidae: Tridacninae) in Palawan, Philippines
DOI:
https://doi.org/10.1590/Keywords:
Abundance, Density, , Population Trend, Species RichnessAbstract
For more than two decades, the Philippine government has protected the giant clams (Bivalvia: Cardiidae:
Tridacninae) from exploitation and trade. However, there still is lack of information on the impact of these protective
measures in conserving the species richness and density, especially in Palawan, the country’s last stronghold
of these reef-associated bivalves. Hence, to assess the species richness and density of giant clams in Palawan,
we conducted 57 photo-transect surveys in six sites covering 12,325 m2
. Out of these transect, 15 measured 5
× 25 m and the rest measured 5 × 50 m. For historical trends in the population of giant clams in Palawan, we
used six published papers obtained from online platforms, 13 reports, and five undergraduate theses archived
in local libraries. Information derived from recent field surveys indicated high variations in species richness (2 to
5 species) and densities (0.1 to > 3.6 ind.100 m-2). Historical data starting from 1984, including recent fieldwork,
indicated very low densities and a declining trend. The current status suggests that giant clam populations’
viability and the reefs’ health are threatened. Effective mechanisms are needed to safeguard and enhance the
remaining giant clam populations.
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