Zoological Studies

Vol. 53, 2014

Rainfall influence on species composition of the ciliate community inhabiting bromeliad phytotelmata

Paulo Roberto Bressan Buosi1*, Laura Roberta Pinto Utz2, Bianca Ramos de Meira1, Bianca Trevizan Segóvia da Silva1, Fernando Miranda Lansac-Tôha1, Fabio Amodeo Lansac-Tôha1 and Luiz Felipe Machado Velho1

1Graduate Program in Ecology of Continental Aquatic Environments, Universidade Estadual de Maringá, Av. Colombo, 5790, Maringá, Paraná 87020-900, Brazil
2Graduate Program in Zoology, Pontificia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681, Porto Alegre, Rio Grande do Sul 90619-900, Brazil

Background: In this paper, we verified the changes in species composition of the ciliate community inhabiting phytotelmata of tank bromeliads in response to seasonality (rainfall). Plants were located at several heights of a great rocky wall on the left bank of the Parana River, southern Brazil. We also assessed if the heights of the plants in relation to the river influence the ciliate species composition. Thus, samplings were performed in the dry and rainy seasons, in three layers of the rock walls (lower, middle, and upper), with a total of 72 samples in both periods.
A relative high number of species and a predominance of hymenostomatids were observed in the sampled plants. Among the recorded species, about 35% occurred exclusively in the dry season. The detrended correspondence analysis demonstrated that the ciliate community changed substantially due to rainfall. However, there was no distinctness in species composition among the strata. In contrast to expectations, the number of species recorded in the dry season was greater than that recorded in the rainy season, refuting the hypothesis that the precipitation volume favors an increase in the number of species.
Conclusions: The rainfall is, undoubtedly, the main factor structuring the community and determining the ciliate species composition in the phytotelmata of the bromeliads. We found that the closeness of the plants with the river is also an important factor for the structuration of the community, due to the dispersion of organisms from the river to the tanks. The occurrence and predominance of planktonic species in the plants at the lower stratum and soil species at the higher stratum indicates a great influence of the neighboring environments on the ciliate community inhabiting the phytotelmata.

Key words: Ciliates; Protozoa; Seasonality; Species composition; Tank bromeliads.

*Correspondence: E-mail: paulobuosi@hotmail.com