Distribution and Diversity of Macrophytes in Relation to Some Physico-Chemical Factors in the Ketar River, Ziway Catchment, Ethiopia

Abstract Distribution and diversity of macrophytes in relation to some physico-chemical factors in the Ketar River were studied from December, 2017 to November, 2018. Physico-chemical parameters and macrophytes were collected from three stations along the river for eight months. Onsite measurements and laboratory work of physico-chemical was analyzed as recommended by APHA [31]. Macrophytes were collected manually using belt transect method. Except for pH and surface water temperatures, all the physico-chemical parameters measured showed no significant difference spatially. During the study period, sixteen macrophyte species belonged to fourteen families were identified. Among the identified macrophyte, 11 of them were emergent, while 3 were rooted with floating leaves and 2 free-floating. Free-floating macrophytes were shared the highest abundance followed by emergent. This research observed that the site (site 3) that was exposed to minimal human impact was rich in diversity and abundance of macrophytes. All the sites were dominated by emergent macrophytes that attained the highest relative frequency followed by rooted emergent species. Azolla nilotica and Pistia stratiotes were shared the highest abundance and were the dominant macrophyte with the relative frequency of 7.24% and density of 40.91%, and 7.93% and 26.54%, respectively. Under a favorable environment, nutrient loading from nearby creates more favorable conditions for the infestation of the invasive species (A. nilotica and P. stratiotes) to flourish and out-compete the other species of macrophyte. Therefore, anthropogenic activities that enhance nutrient addition to the River should be regulated.