Water Quality Assessment of Binosawan River and Mistika Creek in Rapu Rapu Island, Albay, Bicol Using Zebrafish (Danio rerid) Early Life Stage Test

Abstract

This study aimed to assess the water quality of Binosawan River and Mistika Creek in Rapu Rapu Island, Albay using zebrafish (Danio rerio) early life stage test (ELST). Zebrafish embryos (two hours post-fertilization) were exposed for 96 hours to water samples taken from Binosawan River and Mistika Creek (as treatments), and Navotas River (as positive control). Physicochemical and heavy metal analyses were undertaken for the treatments. Based on their low mortality, high hatching success, and slow heart rate, results of the zebrafish early life stage test showed that zebrafish embryos exposed to water samples from the treatments differed significantly from those exposed to varying concentrations of water samples taken from Navotas River. It was observed for all water samples that time of exposure was significant based on hatching success and heart rate. Temperature and pH values of the water samples from Binosawan River and Mistika Creek were all within the tolerance range for survival of zebrafish while alkalinity and hardness values were low. Cadmium, chromium, copper, and zinc concentrations of the water samples from Binosawan River and Mistika Creek were all within the standard limits for freshwater ecosystems. Considering heavy rainfall and turbulent waters during the time of sampling, results tend to show that water quality for Binosawan River and Mistika Creek were generally found to be within acceptable limits. Findings under these conditions could not be conclusive. It is suggested that other methods (e.g. sediment quality analysis) be undertaken.