Combined Effects of Temperature and Salinity on Hatching and Larval Survival of Commercially Important Tropical Sea urchin, Tripneustes gratilla (Linnaeus, 1758)
Md. Shamim Parvez
Earth Solution Ltd., House # 33, Road # 4, Dhanmondi, Dhaka-1209, Bangladesh.
M. Aminur Rahman *
Department of Fisheries and Marine Bioscience, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore-7408, Bangladesh and World Fisheries University Pilot Programme, Pukyong National University (PKNU), 365 Sinseon-ro, Nam-gu, Busan-48547, South Korea.
Md. Jahidul Hasan
Department of Fisheries, Fish Inspection and Quality Control, Matshaya Bhaban, Boyara, Khulna-9200, Bangladesh.
Md. Habibur Rahman
Department of Fisheries and Marine Bioscience, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore-7408, Bangladesh.
Nawshin Farjana
Department of Fisheries and Marine Bioscience, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore-7408, Bangladesh.
Md. Habibur Rahman Molla
Department of Biology, Faculty of Science, King Abdulaziz University, Jeddah-21589, Kingdom of Saudi Arabia.
Sang-Go Lee
World Fisheries University Pilot Programme, Pukyong National University (PKNU), 365 Sinseon-ro, Nam-gu, Busan-48547, South Korea.
*Author to whom correspondence should be addressed.
Abstract
The combined effects of temperature and salinity on percent hatching, normal larval rate at hatching, and survival of fasting larvae after hatching (survival activity index; SAI) of the commercial species of collector sea urchin, Tripneustes gratilla were investigated in a captive laboratory condition. The study was conducted by setting different levels of temperatures (24°C to 36°C) and salinities (38‰ to 23‰). Within the range of temperature from 24 to 36°C and at 32‰ salinity, hatching and normal larval rates, and SAI values were highest at 24 and 27°C. The highest hatching and normal larval rates were found at 35 and 38‰ within the salinity range of 23-38‰; however, SAI value was the highest at 26‰. The results of the experiments in each level of temperature (24, 27 and 30°C) with each salinity (32, 35 and 38‰) indicated interactive effects of temperature and salinity, and within the experimental protocols of 24°C at 38‰ gave an optimal combination for highest hatching and survival of T. gratilla. The findings obtained from the present research would not only be immensely helpful towards the understanding of the suitable temperature-salinity interactions but also facilitate the development of captive breeding, larval raising and mass seed production of this high-valued sea urchin for commercial aquaculture.
Keywords: T. gratilla, temperature, salinity, hatching rate, normal larval rate, survival activity index.