Zooplankton communities as an indicator of ecosystem productivity in Lake Tinishu Abaya, Rift Valley, Ethiopia

Abstract

The ultimate objective of this study was, to explore community structure and biomass of zooplankton in relation to key environmental drivers to bear out the productivity of Lake Tinishu Abaya. Zooplankton samples collection was carried out for a year from January to December 2016 from two sampling sites (open and shore) using 30 µm mesh size net within the euphotic depth. Biomass of zooplankton was anticipated using length-weight regressions adjusted for the representative microcrustacean and biovolume of Rotifera from linear dimensions applied to simple geometric formula appropriate to body shape. In parallel, in-situ and laboratory measurements of the various physicochemical factors were performed using the standardized method. The results of the present study are given strongly generalized that Rotifera had the highest number of species (11 species) followed by Cladocera (5 species) and Copepods (2 species). Diversity parameter, the Shannon diversity index was higher for Rotifera (2.45) than cladocerans (2.395) and copepods (2.384). The mean total biomass of copepods, cladocerans, and Rotifera were 174.4, 46.76 and 13.67 µg/L at open site and 101.8, 51.35 and 10.9 µg/L at shore site, respectively. Physicochemical factors responsible for the observed variations in the biological features of the lake generalized that the lake water was fresh, well oxygenated, slightly warm, alkaline, very turbid, and with relatively high inorganic nutrients. The presence of fairly high diversity, abundance, and biomass of zooplankton in the study shows that the ecosystem of Lake Tinishu Abaya is chemically, physically and biologically productive which supports most of the aquatic life.

Fisheries in Lake Tinishu Abaya (Ethiopia) could be managed using dietary nature of Nile tilapia (Oreochromis niloticus L. 1757)

“…The lake is relatively small, covering 1,253 hectares of land (Kassahun et al, 2011). The depth of the lake was ranged from 2.9 m to a maximum of 3.7 m. As the depths of the lake indicate, Lake Tinishu Abaya is shallow and productive (Enawgaw & Lemma, 2018). The eastern shore of the lake's landscape defines the shape of the lake -oval shape (Fig.…”

Ecological productivity of Lake Tinishu Abaya in relation to photosynthetic productivity and biomass of phytoplankton, Rift Valley, Ethiopia

“…In addition, zooplankton and insects constituted minor portion of the diet of O. niloticus in Lake Tinishu Abaya. 11 According to Yirga 12 the major phytoplankton taxa which was identified in Lake Tinishu Abaya includes Bacillarophyta (15 species), Chlorophyta (11 species), Cyanobacteria (7 species), Euglenophyta (2 species), Dinophyta (1 specie), and Cryptophyta (1 species). The zooplankton communities which were found in Lake Tinishu Abaya were the large-sized crustaceans (copepods and cladocerans) and the smaller rotifers.…”