Characterization of physicochemical parameters and insect composition in a reservoir in Northern Akwa Ibom State, Nigeria

Abstract

This study was conducted in a reservoir located in Mbiabet Ikot Udo community, Northern Akwa Ibom State, Nigeria, to assess the physicochemical status, composition and abundance of aquatic insects. Samples were collected from June 2022 to January 2023 and all the parameters were evaluated using standard methods. The results revealed that temperature ranged from 22.7 to 30.6°C, TDS (153 – 238 mgL-1), EC (153 – 238μScm-1), TDS (97.9 –152.3mgL-1), pH (6.3 – 8.1), DO (2.22 – 5.14 mgL-1), TSS (1.62 – 6.34 mgL-1), NO-3 (1.53 – 5.68 mgL-1), PO-4 (2.18 – 4.16 mgL-1), Mg2+ (3.92 – 5.36 mgL-1), Ca2+ (5.39 – 8.13 mgL-1), Na+ (0.72 – 2.37 mgL-1), K+ (0.68 – 1.48 mgL-1), BOD (1.34 – 6.46mgL-1), Ni (0.001 – 0.08 mgL-1), Fe (0.1 – 0.3 mgL-1), Pb (0.003 – 0.008 mgL-1), Cu (0.01 – 1.3 mgL-1) and Cd (0.002 – 0.008). There were significant temporal variations in some of these parameters. However, all the parameters were within the acceptable limits, except for TSS, BOD, DO, Ni, Cu and Fe. A total of 185 species of aquatic insects, in five taxonomic orders and 10 families, were recorded. Odonata had the highest percentage (40.5%), followed by Hemiptera (25.0%), and Diptera had the lowest percentage (8.6%). The dominant family was Aeshnidae (18.9%) while the least percentage was from Pleidae (1.1%). The analysis revealed that parameters such as temperature, DO, pH, Ca2+, EC, TDS and Cu negatively influenced the abundance of aquatic insects coupled with seasonal influence.