Habitat, morphology, population genetics and reproductive biology of hard clam (Bivalvia : Veneridae) from two locations in Sarawak

Biology and habitat characteristic of most common and abundance hard clam Meretrix spp. was investigated at two selected division of Sarawak namely Kuching and Betong from May 2013 to April 2014. Both areas comprised intertidal areas with sandy type sediment which able to support the growth of Meretrix spp. Environmental factor play important role to influence biology and physiology of Meretrix spp. for the present study. Habitat area for Meretrix spp. in the present study recorded the concentration of hydrogen ion (pH) range from 7.73–8.31, total dissolved solid 35.358–50.467 mg/L, salinity 22.5–31.8 psu, temperature 25.3–27.7 °C, turbidity 82.9–999 ntu, conductivity 3.473–4.683 S/cm, dissolved oxygen 3.74–5.58 mg/L, total rainfall 162.6–729.4 mm, ammonia 0.023–0.223 mg/L, nitrite 0.004–0.017 mg/L, nitrate 0.167–1.233 mg/L, phosphate 0.097–0.43 mg/L, total suspended solid 0.041–0.147 mg/L and chlorophyll a 0.419–0.147 μg/L. A total of 3 hard clam species identified based on morphological characteristic were Meretrix lyrata, M. meretrix and M. lusoria. Pallial sinus scar profile was the main morphological characteristic used for the differentiation of these 3 Meretrix spp. While, a total of 13 morphometric characteristics were used to differentiate the three species of Meretrix recorded from Sarawak. Significant differences (ANOVA, p