Intra-annual variation in planktonic ciliate species composition (Protista: Ciliophora) in different strata in a shallow floodplain lake

Felipe Rafael de Oliveira,Gustavo Mayer Pauleto,Luiz Felipe Machado Velho,Bianca Trevizan Segovia,Fernando Lansac-Tôha,Paulo Roberto Bressan Buosi,Bianca Ramos Meira

doi:10.1590/s2179-975x5817

Felipe Rafael de Oliveira, Gustavo Mayer Pauleto + Show 5 more

Open Access

https://doi.org/10.1590/s2179-975x5817

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Abstract

Abstract Aim: We aimed to evaluate the variation in planktonic ciliate species composition in different strata of the Guaraná Lake, encompassing high and low water periods, at the Upper Paraná River floodplain. Methods Samplings were collected monthly between March 2007 and February 2008, from the epilimnion, metalimnion and hypolimnion. Ciliates samples were filtered using a plankton net of 10µm mesh size and identified in vivo under an optical microscope. Results Among 112 species identified, 13 were found exclusively during the high water periods and 39 during the low water period. Results of nonparametric extrapolation indices evidenced that the observed richness represented between 70% and 90% of the estimated richness. Regarding the variation in species composition, Beta1 index showed that the alteration in composition between strata during the low water period was slightly greater than that registered during high waters. Cluster analysis evidenced a higher dissimilarity in ciliate species composition between periods than among the different strata. The greatest variation in species composition was verified during the distinct hydrological periods, whereas no significant differences were observed for the different strata analysed. Conclusions We found that in the pelagic compartment, ciliate species composition changed significantly between hydrological periods, and a higher similarity in species composition among strata was observed during the high water period. Therefore, alterations in the vertical distribution seem to be related to the homogenizing effect of the floods in the water column stability.

Highlights

River-floodplain systems are characterized by a great diversity of water bodies, including lotic, semi-lotic and lentic environments (Junk et al, 1989)
Aim: We aimed to evaluate the variation in planktonic ciliate species composition in different strata of the Guaraná Lake, encompassing high and low water periods, at the Upper Paraná River floodplain
We found that in the pelagic compartment, ciliate species composition changed significantly between hydrological periods, and a higher similarity in species composition among strata was observed during the high water period

Summary

Introduction

River-floodplain systems are characterized by a great diversity of water bodies, including lotic, semi-lotic and lentic environments (Junk et al, 1989). As opposed to temperate regions, where temperature is the main factor structuring ciliate communities (Graham et al, 2004; Müller et al, 1991), in floodplain habitats of tropical regions the hydrological regime constitutes the major force influencing those protists (Pauleto et al, 2009). This temporal alteration of the hydrological regime provides the occurrence of species that are adapted to this condition, which is facilitated by mechanisms to persist in the environment during unfavorable periods (Lytle & Poff, 2004). Ciliate encystment allows some species to tolerate physical and chemical stresses and reduce their metabolic losses and risk of predation (Taylor, 1981)

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