River health assessment using the fish-based index of biotic integrity and socio-ecological system assessment in selected river systems in Bataan, Philippines

Date

6-2025

Abstract

Riverine ecosystems in the Philippines are increasingly threatened by anthropogenic disturbances, leading to habitat degradation, declining fisheries, and compromised ecosystem health. This situation jeopardized both biodiversity and the livelihoods of dependent local communities. Without a systematic biomonitoring framework, management interventions may overlook key ecological threats and the socio- ecological linkages essential for effective riverine resource governance.

This study evaluated the ecological health of four major river systems in Bataan, Philippines through the development and application of a modified Fish-based Index of Biotic Integrity (FIBI) integrated with diversity index, water quality index, habitat variables, and landscape use metrics. Using ecological indicators such as fish species richness, growth dynamics, trophic composition, diversity indices, and morphometric variation, this research provided an inclusive assessment of riverine ecosystem integrity across upstream, midstream, and downstream gradients of the four studied river systems in two sampling seasons. A total of 2,095 fish individuals representing no less than 55 species were recorded, with spatial variation in FIBI scores linked to anthropogenic stressors and landscape use patterns. Upstream reaches consistently exhibited higher FIBI ratings and ecological integrity, while midstream segments were impaired due to elevated nutrient load, fecal coliform, and biological oxygen demand. Exotic cichlids dominated in midstream areas, whereas native species were more prevalent in forested and less-disturbed areas. Significant positive linear correlations were observed between FIBI, the water quality index, diversity index, habitat evaluation index, and landscape coverage (positive correlation for forest cover; negative correlation for built-up and agricultural land cover), validating the efficiency of FIBI in reflecting ecological gradients. Habitat characteristics such as substrate types, depth variation, and vegetation were identified as key drivers of fish assemblage structure. Socio-ecological system assessments indicated that local conservation awareness positively correlated with FIBI cores, emphasizing the importance of community engagement in conservation management. The study demonstrated the function of FIBI as a cost-effective biomonitoring tool that integrates biological and environmental parameters with implications on informing conservation priorities, guiding adaptive management strategies, and enhancing policy frameworks for improved riverine conservation and Fisheries sustainability.

Document Type

Dissertation

Degree

Doctor of Philosophy in Environmental Science

College

Graduate School (GS)

Adviser/Committee Chair

Maria Victoria O. Espaldon

Committee Member

Patricia Ann A. Jaranilla-Sanchez, Christine Marie E. Casal, Decibel Y. Faustino-Eslava, Hildie Maria E. Nacorda

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

En – AGROVOC descriptors

RIVERS; FRESHWATER ECOSYSTEMS; BIOTIC FACTORS; ECOLOGICAL FACTORS; SOCIOECOLOGICAL SYSTEMS; BIOMONITORING; NATIVE ORGANISMS; SPECIES DIVERSITY; WATER QUALITY; HABITAT SUITABILITY; LANDSCAPING

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