Ecologia e Fisiologia - Comunicações orais

Although the righting behavior of echinoderms is largely used as an indicator of stress, there are no studies correlating this behavior with the true physiological status of the individuals. Here, the righting behavior of Echinometra lucunter was investigated during an experimental fungal infection and correlated to the physiological status of the individuals. Eighteen sea urchins were inoculated with Saccharomyces cerevisiae, at a final concentration of 105 and 107 cells/mL of coelomic fluid (low and high respectively) and the righting behavior, the total and differential coelomocyte counts (TCC and DCC) and cell viability were compared to the controls after 24h. The righting time was 87.0±30.4s in the controls but increased to 99.3±36.6s and 129.8±39.4s in low and high-infected individuals respectively. Regarding the coelomocytes, the TCC was 8.4±1.4x10⁶ cells/mL in noninfested animals but increased to 10.6±3.3x10⁶ and 11.3±2.9x10⁶ in low and high-infected urchins. For DCC, the phagocytes increased by 9.3% and 11.1% in low and high individuals, while vibratile cells decreased by 6.2% and 20.6%, respectively. The red and colorless spherulocytes were very similar among the controls, low and high-infected echinoids. Lastly, the coelomocyte viability in the controls was 78±4%, decreasing to 76±2% and 65±10% in low and high-infected sea urchins, respectively. The results showed that, although the physiological condition of the innoculated individual had consistently differed from the controls, the righting behavior seemed to be altered only after the more severe physiological challenge observed in high-infected animals. These results show that more studies are necessary to understand the extent to which the righting behavior may be useful in predicting echinoderm health status.