Searching the Virtually Extinct Tridacna gigas (Linnaeus, 1758) in the Reefs of Palawan, Philippines

Tridacna gigas (Cardiidae: Tridacninae) is the largest extant reef-associated bivalves that occur abundantly in the Indo-West Pacific Region. However, unregulated exploitation had caused localized extinction in many parts of its distribution range. In Palawan, the species was considered virtually extinct in the 1980s, and since then, no study has been done to monitor their status in the wild. In the absence of updated studies about T. gigas, we gathered information through field reports, key informants, and field visits. Within five months of data gathering, we recorded 97 empty shells (14 in pairs and 83 single shells) with 65.86 cm (range: 42-112 cm) average shell length, which were estimated to be from 5 to >76 years old. Most (78.36%) of the empty shells were used for decoration and landscaping. On the other hand, 29 live individuals with 73.69 cm (range: 42-109 cm) average shell length were estimated to be 5 to >76 years old. Tubbataha Reefs Natural Park and some island resorts harbored the highest number of live T. gigas. The presence of live T. gigas in these areas reflects years of effective management and the resorts’ essential contribution to resource conservation. These remaining live individuals could be used in breeding and restocking programs to restore their lost populations.

KEPADATAN MEGABENTOS PADA EKOSISTEM TERUMBU KARANG DI PERAIRAN DESA PERLANG BANGKA TENGAH, BANGKA BELITUNG

This study aims to analyze the density of megabenthos in coral reef ecosystems in the waters of Perlang Village. This research was conducted in November 2019 in the waters of Perlang Village with the megabentos data collection method using the Bentos Belt Transect (BBT) method based on COREMAP CTI LIPI (2017) with 5 data collection stations. The results found 603 individuals consisting of 9 species from 4 megabenthos families in coral reef ecosystems. Species found at the study site are Diadema setosum, Diadema antillarium (Familli Deadematidae), Drupella cornus, Drupella rugosa (Family Murcidae), Trochus sp, Trochus conus, Tectus pyramis (Family Trochidae), Tridacna gigas, and Tridacna maxima (Family Tridacnidae) . The highest attendance percentage of all stations was obtained by Diadema setosum of 47.93% (289 people). Percentage of live coral cover from 5 observation stations ranged from 57.44% - 91.78%. Observation pensions that received the highest percentage of cover values ​​were at pension 2 with 91.78% in the very good category.

Managing Giant Clams in the South China Sea

Tridacna gigas, the world’s largest living bivalve, could once be found on shallow coral reefs across the Indo-Pacific Region where its presence can be traced back to around 10 million years. However, following several local extinctions throughout its geographic range, its SCS population appears to have also been the subject of unprecedented overharvesting. This article discusses the obligations of littoral States of the SCS to protect and preserve this threatened resource and its habitat, to cooperate and consult with each other to that effect and act with due diligence. Given these obligations and the risk of irreversible harm and species’ extinction in the SCS, it proposes that littoral States should proceed to list the SCS population of T. gigas in the CITES Appendix I, impose an immediate ban on further harvesting pending (re-)assessment of the population, and adopt a management plan to ensure its survival and sustainable use.

Diversity and abundance of giant clams in Anambas Islands, Indonesia

Giant clam is one of the most common types of bivalves found in coral ecosystem. Geographically, these clams have limited distribution in the Indo-Pacific tropics, from the Red Sea to the Pacific Islands of Tuamotu. Ecologically, the clam acts as bio-filtration and natural bio-deposition. The presence of clams becomes a marker that the waters are still good and the absence of harmful pollutants. The population of this clam in Indonesian waters continues to decline. Anambas archipelago are known for its rich diversity of marine life. Since the establishment of this area became NACA as an ATP in 2014, marine tourism activities grew rapidly. Therefore it is necessary to do this research which aims to know the diversity of species and abundance of clams in the waters of Anambas Islands. Field survey was conducted in August 2015 by using Belt Transect method. The research results found 6 species with D1 value is 0.593. The overall abundance is 0.144 indv.m-2. Tridacna crocea has the highest abundance and relative abundance of the highest species of the other species of 60.54%. Meanwhile, the smallest relative abundance is Tridacna gigas which is only 2.36%.