Fluctuating asymmetry in the body shapes of goby fish Glossogobius giuris from Agusan River, Butuan City, Agusan del Norte, Philippines

This study was led in determining the health of area in Agusan River, Butuan City, Agusan Del Norte by looking into the level of fluctuating asymmetry (FA) in populations of Glossogobius giuris. Numerous studies have shown that obtaining the FA can be used to evaluate the water quality including the health of the ecosystem. In this study, G. giuris was used due to its abundance in the area. Thinplate spline (TPS) series was used for landmark analyses of each sample and were subjected to Symmetry and Asymmetry in Geometric Data (SAGE) software. Results of the Procrustes ANOVA showed that individual symmetry of L-R sides presented were not significant. However, variations in both sides of the sexes were identified to be highly significant (p < 0.0001). The results of Principal Component (PC) scores present a high percentage FA of female (71.33%) and male (93.3611%), respectively. In females, all landmark points were affected in PC 1 (47.06%) and PC2 (17.32). In males, PC 1 (60.8437%) and PC 2 (18.913%) have all landmark points affected except for PC 2, where posterior end of the nuchal spine, ventral end of lower jaw articulation, posterior end of maxilla, anterior and posterior midline of orbit, dorsal end of operculum and dorsal base of pectoral fin were not affected. This study validates the use of FA in assessing the status of the ecological health of Agusan River.