Health status of blood cockle's Tegillarca granosa (Arcidae: Bivalva) from three different farms along the Strait of Malacca

The annual production of Tegillarca granosa in Perak and Selangor is constantly decreasing since 1996, however a different production pattern was reported in Johor where it was fluctuated for the past years. Thus, this study was done to provide information on the health condition of T. granosa through morphological observation of the biological attributes and the anatomy of the gill’s tissue. Sampling work was done in dry seasons between May and July 2019 at Bagan Pasir Laut, Perak, Kuala Sungai Buloh, Selangor and Sungai Ayam, Johor. A group of 22-30 T. granosa were collected randomly from each site for biological attribute measurement and the mean were analyzed using Kruskal-Wallis. Six to seven cockles with shell length ranging 25.00 – 35.00 mm were selected for the gill’s histological observation. Fresh T. granosa samples were preserved in 10% formalin before dissection and then the gills were fixed in Bouin's solution, followed by histological standard procedures and haematoxylin and eosin staining. Results indicated a significant difference of biological attributes was detected between the sites with the lowest measurement found in samples from Bagan Pasir Laut. The highest body weight (14.08g) was found in samples from Kuala Sungai Buloh, followed by Sungai Ayam (10.81g) and then Bagan Pasir Laut (8.08g). The histology of the gill filaments of samples from Sungai Ayam are full of hemocytes, well-structured epithelium cells with cilia in comparison to samples from Bagan Pasir Laut, and Kuala Sungai Buloh. The most degenerated gill filaments were found in samples from Bagan Pasir Laut. Thus, suggesting the unhealthy condition of the gills, affects the shell sizes and body weight of T. granosa between the three established farms.