V3I3P65

Assessment of Riverbank Environmental Integrity Using Dragonfly Assemblage Patterns

Kweezy Niven D. Orillosa¹, Rhogie Chanelle A. De Los Reyes¹, Glory S. Gamis¹, Trisha Mae S. Dela Cruz¹, Kisha Kyle Y. Pasaylo¹, Dainah O. Querong¹, Lloyd E. Gardoce¹, Franky Añora¹, Niño Noel M. Monte¹, Anthony Baja¹, Sulpecio A. Pelarija¹, Nathaniel A. Ecoben¹, and Rence M. Alcala¹, Don D. Atienza¹, and Rodelio B. Pasion, PhD^1*

Abstract

The localized environmental status of riverbank areas in Butuan City and Las Nieves was assessed using dragonfly assemblage patterns as biological indicators. The study employed a quantitative methodology involving four sampling rounds, physicochemical measurements of soil and water, and the computation of the Dragonfly Biotic Index (DBI). Analysis of eight identified species revealed non-uniform environmental integrity. Notably, all species were classified as Least Concern (LC) under the IUCN Red List, indicating a dominance of resilient taxa. Water analysis across San Mateo Old (SMO), Dankias, and Lingayao showed safe TDS (145–195 ppm) and a constant SG of 1.000. However, areas exhibited Highly Alkaline conditions (pH 8.87–9.47) and temperatures between 29.5°C 30.7°C. Dankias showed a critical ORP of -5 mV, signaling low oxygen, while Lingayao remained healthy at 208 mV. Soil analysis confirmed a “Heavy, Very Fine Texture” across areas. Soil pH ranged from moderately acidic (6.57) in SMO to neutral (6.95) in Lingayao. Nitrogen and Potassium were adequate in SMO, slightly deficient in Dankias, and deficient in Lingayao. Phosphorus was adequate in SMO and Dankias but slightly deficient in Lingayao. The DBI classified Lingayao as Disturbed but Recovering (DBI: 1.25), while Dankias and SMO were Highly Disturbed (DBI: 1.00), with Dankias showing very low diversity (H′=0.6207). The study recommends immediate habitat rehabilitation and ongoing monitoring by agencies such as the DENR to stabilize these ecosystems.

Keywords:

Bioindicator, Dragonfly Biotic Index, IUCN Red List, Physicochemical Parameters, Riverbank Integrity, Tungao, Butuan City, Philippines