Based on the 2007 Census conducted by the Central Statistical Agency of Ethiopia (CSA), this Zone has a total population of 2,723,850, an increase of 48.79% over the 1994 census, of whom 1,383,198 are men and 1,340,652 women; with an area of 17,935.40 square kilometers, East Hararghe has a population density of 151.87. While 216,943 or 8.27% are urban inhabitants, a further 30,215 or 1.11% are pastoralists. A total of 580,735 households were counted in this Zone, which results in an average of 4.69 persons to a household, and 560,223 housing units. The two largest ethnic groups reported were the Oromo (96.43%) and the Amhara (2.26%); all other ethnic groups made up 1.31% of the population. Oromiffa was spoken as a first language by 94.6%, Somali was spoken by 2.92% and Amharic by 2.06%; the remaining 0.42% spoke all other primary languages reported. The majority of the inhabitants were Muslim, with 96.51% of the population having reported they practiced that belief, while 3.12% of the population professed Ethiopian Orthodox Christianity
Sampling method and data collection
Three sampling sites were selected for collection of phytoplankton and physicochemical parameters of each wetland. These sampling sites were shore (1), middle (2), and (3) anthropogenic area of the wetlands. Integrated water samples for physicochemical analyses and phytoplankton were collected twice, i.e. first from the end of August to September, 2015 and the second in January to mid February, 2016 to represent samples in the wet and dry seasons respectively.
Physico chemical parameter
To study the physico-chemical parameters of the wetlands Water samples were collected and analyzed for total phosphorus (TP) and total nitrogen (TN). A 125 mL acid-washed (HCl), polyethylene bottles were used to collect sample from surface water and stored in refrigerator before analysis. Form deep water sample were also collected from the Lower Break with an alpha bottle at approximately 1.5 to 2.8 m and transferred to a polyethylene bottle. Samples were analyzed for TP and TN using standard methods in Haramaya university analytical chemistry lab.
Some of the physicochemical parameters were determined by using onsite examinations and subsequently a few of them were measured under laboratory conditions. Parameters like temperature , conductivity (Knick Portamess® 911 conductivity meter), pH (Knick Portamess® 911 pH meter) and oxygen saturation (Knick Portamess® 911 oxygen probe), were measured onsite at each sampling site.
Phytoplankton samples were collected in the same locations within the selected sites of the physic chemical. Plankton net with a mouth aperture of 200 mm and mesh size of 50 ?m was used to collect phytoplankton (algae). All samples were preserved in ten seventy percent alcohol and kept in a cool room in dark for further analysis (as per Eaton etal. 1995; Newell 1977, Smith 1996; Steedman 1976). The phytoplankton samples examined with a microscope and identification to genus or species level on the basis of various taxonomic literature available on phytoplankton (Whitford and Schumacher 1973; Jeji-Bai et al. 1977).