A study of the spatial and temporal diversity and abundance of planktonic flora and fauna of Opa reservoir.,Ile-Ife,Southwest,Nigeria
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Date
2016
Authors
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Journal ISSN
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Publisher
zoology,Obafemi Awolowo University
Abstract
The study investigated the spatial and temporal distribution, composition and abundance of plankton in Opa reservoir, Obafemi Awolowo University, Ile-Ife, Southwest Nigeria over a period of an annual cycle (November 2012 to October 2013). This was with a view to providing a more recent catalogue of plankton flora and fauna and an update on the trophic status of the reservoir.
Quantitative net plankton were collected monthly from both the surface and bottom levels at the three sampling stations established at the dam site, mid-lake and riverine part of the reservoir. The preserved samples were examined and enumerated in the laboratory using light compound microscope at low power magnification (×100) and the scaled pictures of the organisms taken. Relevant and appropriate identification keys were used for the identification of the recorded planktonic species. The data obtained were subjected to descriptive and inferential statistics using SPSS version 21. The trophic state of the reservoir was also determined using Ejsmont-karabin’s Trophic State Index.
A total of eighty-two (82) species of phytoplankton and fifty-four (54) species of zooplankton were recorded from the reservoir. The highest number of phytoplankton species was recorded for Bacillariophyta (31 species, 37.80%) followed by 15 species (18.29%) of Cyanophyta and 12 species (14.63%) of Chlorophyta. A total of sixteen phytoplankton species showed significant seasonal variation during this study period while only seven had significant spatial variation (p ≤ 0.05). Notable bio-indicator phytoplankton species recorded were Anabaena circinalis, Anabaena flos-aquae, Microcystis sp., Aphanocapsa litoralis, and Microcystis aeruginosa. Other pollution indicator phytoplankton species recorded were Synedra ulna, Oscillatoria agardhii, Phacus sp., Surirella sp., Closterium sp., Aphanocapsa sp., and Euglena sp. The order of Zooplankton abundance was Rotifera (57.41%) > Arthropoda (33.33%) > Protozoa (5.56%) > Ciliophora (1.85%) = Cnidaria (1.85%). Of all the zooplankton recorded, four species had significant spatial variation while nine displayed seasonal variations during the study period (p ≤ 0.05). Rotiferic species, which dominated the zooplanktonic fauna were Anuraeopsis fissa, Keratella tropica, Filinia sp., Brachionus angularis, Brachionus calyciflorus, Trichocerca sp., and Polyarthra sp.
The study concluded that Opa reservoir, which is rich in phytoplankton notably Bacillariophyta (diatoms), Cyanophyta (blue-green) and Chlorophyta (green algae), as well as Rotifera (zooplankton), could be classified as a eutrophic lake.
Description
xvii,159p
Keywords
Planktonic flora, Fauna, Reservoir, Spatial, Temporal diversity
Citation
Bolawa,O.P.(2016). A study of the spatial and temporal diversity and abundance of planktonic flora and fauna of Opa reservoir.,Ile-Ife,Southwest,Nigeria. Obafemi Awolowo University