Phytophilous Macroinvertebrates of Floating Nymphaea lotus and Pistia stratiotes in River Orogodo, Niger Delta, Nigeria

Abstract

Phytophilous macroinvertebrates associated with two dominant floating aquatic macrophytes, water lilly (Nymphaea lotus) and water lettuce (Pistia stratiotes) in River Orogodo, Niger Delta were sampled between February and July 2006. The location of both plant species exhibited similar water quality characteristics during the study except for BOD5, pH and nitrate that were significantly different (P<0.05) among the locations of the aquatic plants studied. Twenty-seven (27) species of macroinvertebrates attached to the plants were recognized. Clearly, the dipterans particularly chironomid larvae and water mites (Hydracarina) were the preponderant species contributing over 25% each of the total phytophilous invertebrate density while the annelids were the least, contributing only 0.46% to the total density. The association of macroinvertebrates with these aquatic macrophytes is largely due to the fact that they depend on the macrophytes for shelter, food and also as refuge from predators. No odonate or plecopteran nymph was collected from Nymphaea lotus during the period of the study. It is hypothesized that this plant discharges certain compounds that prevented these nymphs from colonizing it. Furthermore, the general morphology of Pistia stratiotes ensured better colonization by phytophilous macroinvertebrates

Keywords: Nymphaea lotus, Pistia stratiotes, phytophilous macroinvertebrates, River Orogodo, Niger Delta.

Tropical Freshwater Biology Vol. 16 (1) 2007: pp. 75-87