Reproduction status of the angelwing clam, Pholas orientalis (Gmelin, 1791), obtained from Selangor, Malaysia

Abstract

To understand the habitat status of Pholas orientalis offshore of Selangor, which is an important fishing ground in Malaysia, P. orientalis was obtained from the region in August and November 2014. The shell sizes and weights of the specimens were measured, and tissue sections of various organs were prepared, stained with hematoxylin and eosin solution, and observed under a light microscope. The results obtained for the gonads, digestive tube, and midgut gland were summarised, and the results showed that many individuals of both sexes had already reached the mature stage in August, and the maturation was almost synchronised in both sexes. In November, more than 40% of both sexes entered the spawning stage, suggesting that the spawning peak in the region occurred during the rainy season. From observations of the presence or absence of food in the digestive tube and epithelium condition estimation of the midgut gland, food presence in the clams was confirmed in more than 80% of individuals in both months, and the epithelium condition was also good. In addition, from the Global Eutrophication Watch internet homepage, chlorophyll-a concentration data on the fishing ground area were shown as the stable phytoplankton occurrence area. Therefore, these data suggest that suitable food availability is an important factor for the habitation of this species.

Keywords

• angelwing clam
• histological observation
• sexual maturation
• chlorophyll-a
• peninsular malaysia