Ecological Status of a Tropical Inland Water Using Macroinvertebrate Feeding Groups and Sediment Characteristics

Abstract

Changing environmental conditions have an important influence on the functional and structural organization of macroinvertebrates in water. The involvements of macroinvertebrates in Bio-monitoring have focused largely on their distribution pattern in water while neglecting the functional and feeding structure. This study aims to use the structure and habitat preferences of macroinvertebrates to provide reliable information on the ecological integrity of Atori Reservoir. Macroinvertebrates were sampled once every two months from selected sample stations in Atori Reservoir for a period covering both wet and dry seasons of an annual cycle. The collected macroinvertebrates were categorized into functional groups using feeding patterns, habitat preferences and mode of locomotion. The reservoir sediment was also analyzed for selected physico-chemical characteristics. Predators (feeding pattern) and Skaters (locomotion and habitat preference) were dominant in the collection. Many of the functional feeding groups were more abundant in the dry season. In fact, Collector-gatherers and shredders were recorded only in the dry season. There was no significant difference in the seasonal variation in the distribution of the macroinvertebrates in the reservoir. The physico-chemical parameters of the sediment did not vary significantly across the sample stations but paired samples T-test showed significant differences in the seasonal variations of physico-chemical parameters of the sediment in the reservoir The dominance of predators and skaters, which are known tolerant species have implications for the ecological integrity of the water. The dominance of tolerant species and the physico-chemical characteristics of the sediment suggested the presence of mild pollution in Atori Reservoir. Proactive conservative measures should be taken in order to prevent further degradation of the water quality as well as prevention of loss of biodiversity in the waterbody.