Acanthocephala in Paralichthys orbignyanus (Valenciennes, 1839) in the Lagoa dos Patos estuary - Rio Grande, RS

Author: Amanda Duarte Pimentel  (Currículo Lattes)
Supervisor: Dr Joaber Pereira Junior


Paralichthys orbignyanus (Valenciennes, 1839) is important for fishing and shows potential for cultivation, like other sole that already has a consistent production and that grows annually. To make its cultivation feasible, some studies are necessary, among them those related to its parasitic fauna. Therefore, in this work the ecology of Acanthocephala parasitism in P. orbignyanus is studied through analysis of parasitological indexes (Prevalence, Average Intensity of Infection and Average Abundance), somatotrophic factors of hosts and environmental factors. Necropsies were total (n = 91). The collected acanthocephalans remained in the distilled water for 24 hours and were then fixed in AFA. The parasites were stained with Semichon carmine and mounted on permanent slides with Canadian balm.In this study, the first description of larval forms of this species in paratenic hosts was presented. Specimens of Southwellina hispida and Corynossoma australe were found in the forms of cystacanth in the host mesentery. The morphometric comparison between cystacanths and adults of S. híspida shows allometric growth of the larvae. The larvae proboscis grows faster in relation to the trunk and this suggests a way to guarantee efficient fixation at the moment the parasite reaches the appropriate final host. There was no correlation or significant difference between the intensity of registered infection and the observed environmental factors. As well as there was no correlation and differences between factors related to the host such as weight, length, diet items and sexual gender.These results suggest that the local estuarine conditions represent a viable scenario for the cultivation of P. orbignyanus since, in net tanks where the inevitable contact with the adjacent fauna occurs, which would make viable S. híspida infections, normally harmful, seem not to succeed.