Do subtoxic levels of chlorate influence the desiccation tolerance of Egeria densa?
Among the different factors hypothesized to be responsible for the virtual disappearance of Egeria densa, once a dominant aquatic macrophyte in a southern Chile wetland ecosystem, are the negative effects of certain chemical compounds (mainly chlorate) and harsh environmental conditions (desiccation caused by prolonged atmospheric exposure). We performed an integrated experiment in which E. densa plants were first exposed for 4 weeks inside a mesocosm system to levels of chlorate that existed in the wetland at the time of the plant's demise and then exposed to desiccation conditions that also resembled those that the system had experienced. Hence, we tested the hypothesis that E. densa plants exposed to sublethal levels of chlorate are more susceptible to the deleterious effect of desiccation compared with plants that had not been exposed to chlorate. This hypothesis was tested by means of quantifying physiologically related parameters in plants right after the 4 weeks under water and then after the desiccation period of 6 hours. Our results rejected this hypothesis, because all plants, regardless of their history, are equally affected by desiccation. Environ. Toxicol. Chem. © 2012 SETAC