Relação entre Ciliado Peritríqueo (Ciliophora: Peritrichia) e o Copépode Notodiaptomus Coniferoides (Crustacea) em um Lago Amazônico

Abstract

Studies show that epibiont peritrich ciliates from zooplankton organisms have great potential as indicators of environmental changes, especially in limnic ecosystems. In order to evaluate the influence of bauxite tailings on the epibiotic relationship between ciliates of the genus Epistylis and copepods of the species Notodiaptomus coniferoides in an Amazonian lake, as well as the potential action of the flood pulse on this relationship, samples were collected in March 2015 (flood period) and June 2019 (flood period), at twelve sampling points on Lake Batata (Oriximiná, Pará): six points in the natural area (NA) and six in the impacted area (IA) due to the presence of bauxite tailings. This study is the first record of Epistylis sp. on copepod N. coniferoides, as well as the first record of this epibiotic relationship in Amazonian ecosystems, among these species. The main attachment sites for Epistylis sp. on the copepod were the dorsal region of the last thoracic segments and the first abdominal segment. There was a clear separation between the natural and impacted areas, based on the environmental variables analyzed (PCA), and a strong correlation between the abundance of epibiont ciliates and the density of prokaryotes (RDA). Although a greater prevalence, abundance and intensity of infestation of epibionts has been observed in the period of flood, this issue needs to be better clarified in future studies. There were also significant differences in ciliate abundance and density of prokaryotes between the impacted and natural areas of the lake (ANOVA). We conclude that there are extrinsic factors related to the environmental characteristics of the lake, such as suspended material and turbidity, and intrinsic factors linked to the density and behavior of the host as well as food availability influence the abundance, intensity and prevalence of epibiont infestation between the analyzed areas (NA and IA). The work opens questions for further in-depth investigations: (1) is the epibiont ciliate found a new species?; (2) are there other potential hosts for this ciliate in the lake or is the relationship highly specific ?; (3) does the flood pulse in the lake influence this epibiotic relationship?; (4) since turbidity is an important environmental factor in this lake, is the higher prevalence in the sampling points of the impacted area directly related to the suspended material (food availability) ?.