Biodistribution Profile of Freshwater Mollusks Across Tributary Gradients as Indicators of Ecological Stability

The study focused on collecting, identifying, and establishing a mollusk species profile within three tributary stations in Butuan City using a descriptive research design employing a transect line sampling method from August to September 2025.Physicochemical analysis revealed alkaline pH (8.426-8.648),TDS (154.0-222.4mg/L), and S.G. (1.00) across stations within standard, but critically low ORP values (70.8-136.6 mV) indicated environmental stress.A total of 7,991 individuals representing 9 families were collected, with Station 1 (Manila de Bugabus) contributing 82.94%, Station 2 (San Mateo) 6.52%, and Station 3 (M.J. Santos) 10.53%.Dominant gastropod species included Melanoides maculata (33.85%), two Pomacea species (16.41% and 18.79%), and Corbicula fluminea (84.32% of bivalves).Most mollusks exhibited random distribution in muddy substrates, with IUCN status ranging from Least Concern (LC) to Not Evaluated (NE).All stations showed very low diversity (H' 0.535-1.920)and low species richness (DMg 0.445-1.279).Evenness varied from less balanced at Station 2 and Station 1 (J 0.409-0.427)to semi-balanced at Station 3 (J 0.758).Three stations vary in dominance: Station 2 (D 0.2729) low, Station 1 (D 0.6287) moderate, and Station 3 (D 0.8232) high in dominance.The study highlights the influence of localized anthropogenic occurrence within tributaries, contributing to alarmingly low ORP, combined with poor diversity indices indicates ecosystem instability, necessitating immediate monitoring and targeted conservation strategies.