The DisappearingFish Community in Butuanon River, Cebu, Philippines: The Ignored Impact of Pollution

Aims and Objectives: This study generally assessed the impact of the Butuanon river water quality in terms of the abundance and richness of freshwater fish community. Specifically, this study compares 2009 and 2019 fish abundance and richnessofButuanon river in Cebu, Philippines. Methodology:Test fishing from random stations along the entire length of the Butuanon river were conducted on April 2009-July 2009 and on June 2018-February 2019. All sample specimens were stored in 10% formalin and brought to the laboratory for further processing. Likewise, in-situ and ex-situ measurements of water quality parameters were taken, particularly water temperature,pH, dissolved oxygen (DO), and total suspended solids (TSS). Results:All of the fish species documented in Butuanon river are hardy species which can tolerate wide ranges of aquatic environmental conditions. In 2009, seven (7) species of freshwater fish were documented while there were only four (4) in 2019. Comparing the 2009 and 2019 data,a 42.9% reduction of species richness of fish in Butuanon river is alarming. Similarly, there was a significant (p-value< 0.05) decline in DO readings between 2009 (32.67 mg/L ± 1.95) and 2019(4.5 mg/L ± 0.27) while there was a dramatic increase in the TSS readings between 2009 (0.67 mg/L ± 0.02) and 2019 (123.3 mg/L ± 9.12). Likewise, temperature and pH measurements significantly (p-value < 0.05)vary between 2009 and 2019 readings. Conclusion:The significant reduction in the richness and/or the disappearance of some freshwater fish in Butuanon river was seen as a reprehensible effect of uncontrolled deterioration of the river ecosystem condition as exhibited by the lowering DO and increasing TSS. Immediate interventions to save the Butuanon river should be taken with utmost serious considerations.