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

Abstract

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. Results: 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.

Ecological Study of the Active Ciliate Community from Bromeliads during the Humid Season in Different Types of Forests of the Mexican Neotropics

“…However, ciliate communities recorded in this study might not have included sessile or thigmotactic species as a result of the employed sampling methodology, the small plant sizes with low volumes of water and the impediment of plant removal from their habitats. The number of plants where active ciliates were absent was higher in comparison to the results of Buosi et al's work [18,19] in bromeliads along the margins of the Paraná River in South Brazil. In spite of the presence of impounded water in almost all the plants, with the exception of nine bromeliads in the dry tropical forest, the richness of active ciliates was lower, in comparison to the 92 species observed in Aechmea distichantha [18,19], with 13 species on average per plant, meanwhile only an average of 1.43 species per plant was recorded in the present study.…”

“…The number of plants where active ciliates were absent was higher in comparison to the results of Buosi et al's work [18,19] in bromeliads along the margins of the Paraná River in South Brazil. In spite of the presence of impounded water in almost all the plants, with the exception of nine bromeliads in the dry tropical forest, the richness of active ciliates was lower, in comparison to the 92 species observed in Aechmea distichantha [18,19], with 13 species on average per plant, meanwhile only an average of 1.43 species per plant was recorded in the present study. Lower richness values were recorded by Busse et al [22] in Quesnelia arvensis Mez.…”

“…The application of α-diversity indexes was useful to compare species richness between localities, but unfortunately they were not very informative due to the low number of samples; although we obtained that there were no significant differences of α-diversity of ciliates between localities of the semideciduous tropical forest, oak and montane cloud forest (K, O, and Z) with the rest of the localities, the other two localities of montane cloud forests (P and T) were different to the α-diversity of ciliates of bromeliads from the dry tropical forest (locality C), because of its almost total absence of active ciliates. Buosi et al [18] emphasized that water was the most important factor for the presence of ciliates in bromeliads; however, our results suggested that even if impounded water was present in bromeliads, other unknown factors could be restrictive for the excystment of ciliates to become active.…”

“…There are only two previous studies about ciliates and bromeliads, which used a similar dataset, considering an ecological and taxonomical approximation [18,19]. Not all the sampled bromeliads in the present study contained active ciliates.…”

“…Some studies that analyzed the influence of biotic and abiotic factors on ciliate communities in tank bromeliads have taken place in small geographic areas and only considered one or a few bromeliad species. Buosi et al [18,19] analyzed the ciliate community in Aechmea distichantha along the margin of the Paraná River in South Brazil, emphasizing the importance of water for the presence of ciliates in bromeliads and the influence of proximity to freshwater bodies as a factor that enhances the colonization of ciliates to bromeliads. In relation to the community composition and structure, they found that species' richness was higher during the dry season in contrast to the abundance, which was higher in the humid season [18,19].…”