Protistas Ciliados (Protista, Ciliophora) encontrados no Córrego São Pedro (Bacia do Rio Paraibuna), município de Juiz de Fora, Minas Gerais: taxonomia, morfologia, biomonitoramento e relações epibióticas

Abstract

In the present study, both taxonomy and morphology aspects of the ciliate protists found in São Pedro stream (Juiz de Fora-MG), as well as their potential as water quality indicators were studied together with the ecological aspects of the epibiotic relation between the ciliate and some benthic macroinvertebrates. The present dissertation is divided into seven chapters. In chapter 1, the survey of ciliate protists was obtained from samples of water and sediment from the stream, during a hole year, and the succession of these protists was observed in laboratory. Forty-two ciliate species were identified and Apoamphisiella sp. n. (Spirotrichea, Amphisiellidae) was morfologically characterized. In chapter 2, mirror-image doublet was described in Gastrostyla setifera (Spirotrichea, Oxytrichidae), obtained from samples of water and sediment at the São Pedro stream. The Chapter 3 registers the presence of Neobursaridium gigas Balech, 1941 (Oligohymenophorea, Neobursaridiidae) in the stream and presents a revision of the morphological aspects of this ciliate, as well as its ecological and geographical distribution. In chapter 4, the influence of the organic pollution on both the composition and the distribution of the taxocenose of ciliate protists along the stream had the aim of evaluating the water quality of this lotic system. During the one year study, 39 ciliate protist species were found, 32 of which were included in the saprobic system and their potencial as indicators are considered. The composition and the distribution of the taxocenose of ciliate protist varied both spatial and seasonally. The saprobic index and the valency methods were used to evaluate the water quality at the five stations and they demonstrated the high degree of pollution on stations 4 and 5. Our results confirm that the organic load in watercourses may be a dominating factor capable of influencing the composition, distribution and trophic structure of the taxocenose of ciliate protist. The following chapters consider the epibiotic ciliate protist associations to mollusks, oligochates and insect larvae. In chapter 5, seven ciliate species were registered on the shells of Pomacea figulina, six of which belonging to the subclass Peritrichia: Carchesium polypinum, Vorticella microstoma, Vorticella campanula, Epistylis plicatilis, Epistylis sp., Opercullaria sp. and one belonging to the subclass Suctoria: Hypophrya fasciculata. Results are discussed in terms of the advantages and disadvantages of this relationship from the ciliate protist point of view, together with the ecological aspects involved in this association. In chapter 6, location ranch and both spatial and temporal distribution patterns of Rhabdostyla peritrichids were found colonizing limnic oligochaetes Tubificidae of the species Limnodrilus hoffmeisteri in the five amostral stations, during 11 months of collection. The occurrence pattern of the epibionts on the oligochaetes was spatial and seasonally heterogeneous. Results are discussed in terms of the possible causes for the site preference of the ciliates in the posterior region of the oligochaetes and factors related to the heterogeneous pattern of space and temporal distribution. Finally, chapter 7 registers the occurrence of Rhabdostyla chironomi (Ciliophora, Peritrichia) on Chironomus decorus larvae (Diptera, Chironomidae) in the stream and still it moderates the factors involved in the location of the ciliates on the ventral tubules of its hosts and the possible usage of this relationship as indicative of the water quality.