Species composition and abundance of benthic species along Cagayan river: Conservation purposes

Abstract

This study generally aimed to provide an update on the benthic community along the Cagayan River. Specifically, this study sought to determine the species composition, economic value, conservation status, and relative abundance of microbenthic invertebrates in the waters of Cagayan River, specifically in Lal-lo (Site 1) and Alcala (Site 2).  Sampling stations were established at each site and a modified transect-quadrat approach was used in the collection of samples. Samples were identified using online published resources and relative abundance was also computed. The results of the study identified seven Mollusk species, with four species under the class Bivalvia and three under Gastropoda. Corbicula sp., Delillia sp., and Batissa violacea were found to be of high economic value, serving as important sources of income for local communities. However, Delillia sp., endemic to the Cagayan River particularly at Lal-lo, is becoming increasingly rare. In terms of conservation status, most species were categorized as “Not Evaluated” on the IUCN Red List, except for one economically important bivalve species, which was classified as “threatened.”  In terms of the relative abundance of benthic Mollusk species in the Cagayan River at Lal-lo and Alcala. Corbicula sp. dominated both sites, representing 63.67% of the total catch at Lal-lo (N=14,673) and 72.18% at Alcala (N=205). Delillia sp. was the second most abundant species at Lal-lo, accounting for 35.74% of the catch, while Melanoides tuberculata was the second most abundant at Alcala with 27.82%. The least abundant species was Batissa violacea, with only 60 individuals recorded (0.26%), highlighting its decline and classification as a threatened species. The abundance of benthic species varied significantly across stations, with Fabrica in Lal-lo being the most abundant collection site (N=7,704). Moreover, Corbicula sp. demonstrated resilience to environmental disturbances, maintaining its economic importance as a consistent source of livelihood for local communities. Thus, the findings of this research study highlight the need for further research on genetic barcoding to provide accurate identification of the samples and conservation efforts to protect these valuable Mollusk species and ensure their sustainable use.