Diversity and Functions of Benthic Macroinvertebrates in Relation to Water and Riparian Conditions in Riverine Channels of Eden and Dibibi, Quirino, Philippines

Benthic macroinvertebrates diversity provides information on the quality of freshwater ecosystems. The dynamics of freshwater body and surrounding riparian zones in Eden and Dibibi, including the ecology of macroinvertebrates, were described in this paper. Various macroinvertebrate indices were used to calculate organic pollution levels. A total of 165 specimens were collected, representing five families, four orders/suborders, and three morphotypes. H’Eden and H’Dibibi have very low alpha diversities (H’Eden=1.43 and H’Dibibi=1.41). For both channels, dominance is distributed to about three taxa (1/DEden=2.90; 1/DDibibi=2.73). Hydropsychidae and Perlidae were the most abundant, indicating a plentiful supply of oxygenated water and perennial water flow. The Hilsenhoff Family Biotic Index (FBI) scale gives Hydropsychidae a TV of 4, indicating that it is somewhat tolerant to polluted water. Highly susceptible families include Perlidae TV=1; Tipulidae TV=3. Perlidae, Tipulidae, and Oligochaeta are also indicators of potential organic pollution. All physicochemical parameters are within “normal”. The Ephemeroptera-Plecoptera-Trichoptera (EPT) taxa and %EPT indices produced indicate that the sampled waters are “moderate” to “very good” condition. Due to the abundance of Hydropsychidae, Hilsenhoff FBI rated the sampled waters of Eden as “Excellent”; Dibibi was slightly lower in quality. Furthermore, the indices indicate the presence of pollution-causing elements, which can be linked to human presence and land uses. The geomorphology of the two river sections’ riparian and lotic zones, including those of upriver, provide resilience against anthropogenic stresses. This is supported by measurements and observations of physicochemical parameters. As a result, management decisions must take into account the enforcement of environmental functions that deter degradation and ensure river ecosystem’s stability.

Keywords: Macroinvertebrates, Hilsenhoff FBI, EPT, Quirino