Abstract
This study looked at species adaptations to different substrate type, current velocity, dissolved oxygen and depth that allows for the specialized utilization of the microhabitats found and how this was responsible for similarities and differences in species diversity in pools and riffles. The riffle was seen as the more diverse mesohabitat. Of the 47 species found, the riffle had 37 of these organisms present. The most abundant species in riffles and pool together were Thiaridae, mytilidae, psphenidae, collembola , Diptera and the Spharidae. The the Shannon diversity index number of 3.162 and 2.903 was recorded for the riffle and pool respectively. The results from the evenness test also show that the pool has a lower level of evenness than the riffle. Evenness results were 0.837 and 0.883 for the pool and riffle accordingly. Within the five most abundant taxa within each mesohabitat, three species were found in both environments. The Psphenidae, Mytilidae and Collembola. The species found in these habitats therefore had special adaptations to allow for such .The main feature to which they must adapt was current velocity which was statistically significant in pool and riffle .
Introduction
Theoretically, regarding the structural and biological dynamics of a pool and riffle system in rivers, riffles and pools tend to support different densities and types of organisms. (Gordon et al., 2013). Although this is so, this applicability to man-made pool-riffle systems have not been extensively addressed. Species diversity can be defined as the richness and abundance of different types of organisms within a given habitat (Anderson et al. 2011). The diversity of species in lotic environment; any system that has a unidirectional flow, is reflective of biotic and abiotic factors. These play crucial roles in influencing the distribution and interaction between species