Abduraji S. Tahil, Danilo T. Dy
The potential effects of reduced pH as a result of an increased CO 2 concentration on settlement and survival of Haliotis asinina larvae were investigated. The settlement frequency (%F) was significantly different with respect to pH levels. On day 5, 100% of the settlement plates contained postlarvae at ambient conditions (pH 7.98) and pH 7.76. Lower %F was obtained at pH 7.41 (12.5%-37.5%) and pH 7.57 (25%-62.5%). Hence, significantly higher number of larvae attached to plates at ambient conditions (16 postlarvae plate -1 ) and at pH 7.76 (10 postlarvae plate -1 ). On the other hand, the concentration of carbonate ion was lowest in the high-CO 2 or reduced pH treatment and the larval settlement was also lower. Fewer larvae settled on plates exposed to pH 7.41 (3 postlarvae plate -1 ) and pH 7.57 (5 postlarvae plate -1 ). Post settlement survival (10 and 15 days after exposure) was significantly lower at reduced pH levels compared to ambient conditions. Settlement rate was also affected by the reduction in % cover of crustose coralline algae (CCA) of the plates and delayed morphological development of larvae at reduced pH. This study confirmed that reduction in pH of seawater to the levels predicted by the end of this century will have negative effect on the settlement and survival of H. asinina larvae, and by extension, the future economy of the abalone industry of the Philippines. © 2015, Science and Technology Information Institute. All rights reserved.
Department of Biology, University of San Carlos, Talamban Campus, Cebu City, Philippines; Mindanao State University Tawi-Tawi, Sanga-Sanga, Bongao, Tawi-Tawi, Philippines
