Journal of the Marine Biological Association of India

Volume 60 Issue 1

Seasonal and positional variations in the rate of nacre coating in Indian pearl oyster Pinctada fucata (Gould, 1850)

R. Mary Rinju, M. K. Anil and E. Sherly Williams

Recently technology has been perfected for the production of quality image pearls (mabe pearls) in India which fetches a good price ranging from $20-50 per pearl. This study focused on variations in the rate of nacre coating during different seasons when implanted with image pearl nucleus in different positions of the pearl oyster shell. The implantation was done at three positions at P1, P2 and P3 in both shells and the experiments were repeated in three seasons namely pre monsoon, monsoon and post monsoon. Among the positions, the position P2 which is the wide marginal mantle region gave the maximum nacre coating rate. Hydrological parameters such as atmospheric and water temperature, salinity, pH, turbidity, ammonia, nitrite, nitrate, phosphate, silicate, dissolved oxygen, primary productivity and chlorophyll a were also recorded during the study. Rate of nacre coating was found to be maximum (6.79 ± 2.07 μ/ day) during post monsoon months corresponding to maximum productivity (Net Primary Production of 204.40 ± 45.86 mgC/m3/day and Gross Primary Production of 361.40 ± 96.92 mgC/m3/day) and chlorophyll concentration (2.79 ± 0.13 mg/m³). The rate of coating was minimum (2.19 ± 0.17 μ/day) during pre monsoon season. The influence of hydrological parameters and positions of the implanted nuclei on the nacre coating were statistically analysed and discussed in the present paper. 


Pinctada fucata, image pearls, mabe, nacre, seasonal variation, hydrology.

Date : 31-07-2018