A decade of Philippine freshwater goby research (2010–2022): a systematic review and meta‑analysis of ichthyofaunal surveys

Abstract

Freshwater goby (Family Gobiidae) is one of the diverse and widespread fish species in rivers and lakes, with economic values ranging from ornamental and subsistence provisions. Several ichthyofaunal surveys have been conducted in the Philippines; however, no systematic review and meta-analysis was performed to analyze freshwater goby species richness over fish species richness. Following the PRISMA Protocol, twenty–three (23) studies were assessed and statistically analyzed using JASP Version 0.18.3. Each paper was reviewed to identify study sites, goby genera, diversity indices (Shannon, Pielou’s evenness, and Simpson), and physicochemical parameters, with correlations analyzed across fish species, goby species richness, and diversity indices. Results revealed that most freshwater goby studies take place in Luzon, and the genus Glossogobius is the prevalent goby species at most study sites. The diversity index for introduced fish species ranged from low to medium, as indicated by the enriched biodiversity index score from Guerrero (2014). In terms of physicochemical parameters, all values generally met the standards set by DAO 2016-08. However, the forest plot revealed that the effect size was entirely on the positive side of zero, with a combined effect size of 0.46, suggesting a moderate impact. The funnel plot indicated an asymmetrical pattern among studies, suggesting potential publication bias. Analysis suggests that goby diversity in the Philippines is high in terms of species richness, with a moderate effect size when compared to overall fish species richness based on the collated studies. Taking into account the high publication bias observed, we recommend including more studies from Southeast Asian countries. Researchers are encouraged to prioritize biodiversity studies in the Visayas and Mindanao regions to mitigate study bias. A comparative analysis of native and introduced fish species richness would also be beneficial in determining their potential impact on the overall effect size of species richness.