Journal of Environmental Biology

Seasonal changes in the rotifer (Rotifera) diversity from a tropical high altitude reservoir (Valle de Bravo, Mexico)

Jorge Jimenez Contreras¹, S.S.S. Sarma*¹, Martin Merino-Ibarra² and S. Nandini¹

¹Laboratory of Aquatic Zoology, Division of Research and Postgraduate Studies National Autonomous University of Mexico,

Campus Iztacala Av. de Los Barrios No.1, AP 314, CP 54090, Los Reyes, Tlalnepantla State of Mexico, Mexico

²Instituto de Ciencias del Mar y Limnologia, Universidad Nacional  Autonoma de Mexico, Mexico, D.F., Mexico

(Received: October 20, 2007; Revised received: March 02, 2008; Accepted: April 10, 2008)

Abstract: We studied the zooplankton community composition at different depths (2, 4, 8, 12 and 20 m) of Valle de Bravo, a drinking water reservoir in central Mexico during December 2005 to November 2006.Temperature, dissolved oxygen, pH and chlorophyll a were measured simultaneously. While physicochemical values were similar to those found in previous studies, total zooplankton abundance was higher (mean 847 ind. l^-1), doubling the mean abundance found in the previous year. Nevertheless, Zooplankton remained dominated by the rotifer genera Keratella, Polyarthra and Trichocerca, which constituted nearly 80% of the total numerical abundances. We encountered 23 rotifer species of which 5 of them (Lepadella rhomboides, Cephalodella catellina, Trichocerca elongata, T. porcellus and Dicranophorus forcipatus) were recorded for the first time from this reservoir. Shannon Wiener diversity index showed that the annual mean species diversity index was similar at depths of 2, 4 and 8 m, but were reduced at 12 and 20 m. Regardless of depth, the highest diversity value of 1.82 was observed during January, while the lowest (0.07) during March. Principal component analysis showed that temperature, dissolved oxygen, water column depth and chlorophyll a have combined effects on the abundance of dominant rotifer species. The highest rotifer density was observed in April (>1600 individuals l^-1), while the lowest was recorded during January (<50 ind. l^-1). During the study period, the most abundant rotifer species were Keratella chochlearis, Polyarthra vulgaris, Trichocecra elongata and Anuraeopsis fissa.

Key words: Zooplankton, Limnology, Plankton, Physico-chemical variables, Eutrophication

PDF of full length paper is available with author (*ssssarma@gmail.com)

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