Behavioral parameters as tools for physiological analyses in echinoderms: Evaluation of the effect of microplastic pollution and an experimental fungal infection on turning behavior in the sea urchin Echinometra lucunter

Abstract

Behavioral analysis in vertebrates are used as a rapid and low-cost tools for monitoring the quality of the environment and the health status of organisms. For invertebrates this is not yet true, as few groups have been consistently studied. One example is echinoderms, where turning behavior - the time it takes an organism to return to its natural position - could be a simple and easy test to perform for these purposes. Although this process has already been used to indicate several types of stresses, there are no studies that confirm or evaluate its relationship with the health status of animals. In this sense, the objective of the present project is to investigate whether the turning behavior really reflects the health status of echinoderms, using as a model urchins of the species Echinometra lucunter. The organisms will be exposed to two different physiological stressors: an experimental infection with the yeast Saccharomyces cerevisiae and exposure to a pollutant, phthalate, an additive present in microplastics. The turning behavior of individuals will be measured and related to different immune parameters: total and differential number of coelomocytes, cell viability, and total protein concentration in the coelom. Thus, besides confirming the usefulness of turning behavior as a bioindicator, understanding how human actions interfere with the quality of the environment and the health of organisms, this project will show how the immune system of echinoderms responds to different stresses, which may help in future biomonitoring studies in the marine environment.