Journal of Environmental Biology

Feeding and filtration rates of zooplankton (rotifers and cladocerans) fed toxic cyanobacterium (Microcystis aeruginosa)

Alfredo P?rez-Morales, S.S.S. Sarma* and S. Nandini

Laboratorio de Zoolog?a Acu?tica, Divisi?n de Investigaci?n y Estudios de Posgrado, Universidad Nacional Aut?noma de M?xico,

Campus Iztacala, A.P. 314, C. P. 54090, Tlalnepantla, Estado de M?xico, M?xico

*Corresponding Author E-mail: sarma@unam.mx

 Publication Data

Paper received:

30 September 2013

Revised received:

11 March 2014

Accepted:

12 May 2014

Abstract

Microcystis aeruginosa is generally dominant in many Mexican freshwater ecosystems interacting with zooplankton species. Hence, feeding and filtration rates were quantified for three cladoceran (Daphnia pulex, Moina micrura and Ceriodaphnia dubia) and three rotifer species (Brachionus calyciflorus, Brachionus rubens and Plationus patulus) using sonicated M. aeruginosa alone or mixed with Scenedesmus acutus in different proportions (25, 50 and 75%, based on cell density), offering a combined initial density of 100,000 cells∙ml-1. All the three cladoceran species ingested M. aeruginosa (100-300 cells ind-1 min-1) when fed exclusively with cyanobacterium. When green alga offered as exclusive diet, the number of cells ingested by the tested cladocerans varied from 80 to 400 cells ind-1 min-1. Compared to cladocerans, rotifers in general consumed much lower quantity (< 200 cells ind-1 min-1) of M. aeruginosa and S. acutus. The filtration rate for Daphnia pulex was inversely related to the proportion of green alga in the diet. For other tested cladocerans, no such clear trend was evident. In mixed treatments containing M. aeruginosa, the filtration rate of Daphnia was highest (about 220 ?l ind-1 min-1) when the medium contained 75% of S. acutus. Among the rotifer species, P. patulus filtered highest volume (100 ?l ind-1 min-1 from mixed diets containing higher proportions (50 or 75%) of M. aeruginosa. Thus, there were species-specific differences in the filtration and feeding rates of zooplankton when offered mixed diets of green algae and toxic cyanobacteria. These probably explain the coexistence of different zooplankton species in Microcystis-dominant waterbodies. ?

 Key words

Feeding and Filtration rate, Freshwater zooplankton, Microcystis aeruginosa, Scenedesmus acutus

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