Coccídios como biomarcadores de impacto ambiental em Passeriformes na Ilha da Marambaia e no Parque Nacional do Itatiaia, RJ

Abstract

Birds establish the dynamics of ecosystems preserved and anthropized, because in addition to the diversity of physical and behavioral aspects, these have several functions in the environment. For this study, the Marambaia Island (IM) was used because it had a history of human presence and preserved fragments of the protected Atlantic Forest and the Itatiaia National Park (PNI), constituted by secondary forest, but preserved by the Atlantic Forest, both in Rio state of January. A total of 377 birds were captured using fog networks at dusk obeying the circadian rhythm of coccidia species, where oocysts were eliminated in the feces more frequently at dusk. Of the captured animals, 190 of them were from IM and 187 from PNI. After being identified, these birds were placed in a bag or in transport boxes until they defecated and then were released at the same capture site. The feces samples were placed in 50 ml Falcon tubes containing a ratio of 1/6 feces to 5/6 2.5% (v / v) Potassium dichromate solution (K2Cr2O7) and maintained at the temperature until 80% or more were sporulated for their generic identification. The most frequent families in the IM ecosystem were Thraupidae, Turdidae and Tyrannidae with 44.73; 19.47 and 14.21% respectively, and the other families frequently below 6.32%. The species most adapted to the anthropization of the IM were those of the Thraupidae family, where the Brazilian tanager (R. b. dorsalis), the Palm tanager (Thraupis palmarum) and the Blue dacnis (Dacnis cayana) more prevalent, although the species of Tyrannidae are expressive among the families found in the region. The percentage of risk was still related to greater intensity to the species of the family Thraupidadae where there were 25 parasitized for a total of 65 specimens. Of the specimens captured, 17 of the positive animals were part of the subfamily Tachyphoninae, where the Brazilian tanager was the most parasitized with 12 positive specimens for Isospora oocysts in the feces. The food habit in relation to the percentage of risk for coccidia infection was important and was always related to the species with a high risk of infection due to having frugivorous habits and being docile birds against the birds of the omnivorous habitat and insectivores both of the understory. In addition, frugivorous birds are more likely to acquire coccidia infection 3.593 times compared to omnivores and 3.153 times against insectivores, respectively, in this remnant area of the Atlantic Forest with strong anthropization. In addition, canopy species in turn have 3.0213 times more chances of acquiring the infection in relation to understorey birds on the IM, RJ. In PNI, the most prevalent families in the productive ecosystem of the park were Thraupidae, Thamnophilidae, Dendrocolaptidae, Rhynchocyclidae, Pipridae, and Turdidae with 26.74, 14.96, 8.56, 8.56, 7.49 and 7.49% respectively, and the other families often below 7.00%. The species most adapted to the PNI ecosystem were those of the Thraupidae family, among them Ruby-crowned tanager (Tachyphonus coronatus), but the presence of the White-shouldered Fire-eye (Pyriglena leucoptera) of the Thamnophilidae family were the most predominant in the region studied. The percentage of risk was still related to higher intensity to the species of the family Thraupidae where there were 34 parasitized for a total of 50 specimens. Of the specimens captured, 21 of the positive animals were part of the subfamily Tachyphoninae, where the Ruby-crowned tanager was the most parasitized with 15 positive specimens for oocysts of species of the genus Isospora in the feces. The food habit in the face of the chances of infection by coccidia was not important based on the trophic quilds, since the infection was observed in this forest ecosystem with the predominance of the insectivores typical of forest densification. Canopy versus understory species did not have a representative risk of acquiring coccidia infection in a forest ecosystem, as would be the case with PNI. Compared to the two ecosystems, MI and PNI, it was observed that the former had a strong anthropization over time where the families of insectivorous birds did not have the same density as the frugivorous; while in PNI the presence of insectivorous birds were well represented and parasitized in an equitable way by coccidia showing a perfect balance, typical of a forest ecosystem that presents birds parasitized in enzootic equilibrium, determining with this the fragility of this, if disturbed.