The Effects Of Dye On Cercariae

Parasites can reach high abundance and biomass in estuaries. As such, they can influence the ecosystem at individual, population, and community levels.  Some parasites require two or three hosts to complete their life cycle. The ecology of a parasite and its effects on an ecosystem is dependent on many factors including host-specificity, the number of hosts a parasite can successfully infect at a particular stage.  Acanthoparyphium spinulosum is a parasite that lives in estuaries along the Pacific Coast of North America. This parasite has a broad host-specificity at the second intermediate host stage of its development and is capable of infecting many molluscs and polychaete worms. To gain a better understanding of this parasite’s host-specificity, we conducted several laboratory experiments.  Here we present data for the use of a fatty-acid analog fluorescent dye as a possible aid to experimental infections. We examined the effects of three concentrations of dye on cercariae in order to identify an ideal concentration which will fluoresce and be detectable for identification without affecting the cercariae’s behavior or ability to infect hosts. The high concentration of dye had a significant negative effect on the survivorship of the cercariae (p<0.01). All other concentrations showed no significant difference in survivorship from the control. The dyed cercariae were later used in experimental infections of some representative secondary hosts- Polydora nuchalis and Tagelus californianus. Results from this study will further current understanding of A. spinulosum’s host-specificity as well as aid in the experimental design of future experimental infections.