Experimental validation of the relationships between cubozoan statolith elemental chemistry and salinity and temperature

Abstract

Knowledge surrounding the movements of jellyfish is limited, but elemental chemistry has the potential to elucidate these movements. The objective of this study was to experimentally validate elemental chemistry as a technique which may provide insight into the movements of cubozoans. The approach used a laboratory experiment on the well-known cubozoan species Chironex fleckeri, examining the relationship between statolith elemental chemistry and temperature and salinity. Strong evidence was found that statolith Sr:Ca varied with temperature and that this was independent of variation in salinity. Sr:Ca ratios in saltwater varied little with variation in temperature or salinity. Accordingly, a physiological mechanism within C. fleckeri must have affected statolith Sr:Ca, causing it to vary with temperature. Based on the experimental data from this study and correlative evidence that Sr:Ca varied with temperature in another cubozoan, Copula sivickisi, we provide robust evidence that statolith Sr:Ca can be utilised as a proxy for temperature and may be applicable to other species of cubozoans. Ba:Ca in statoliths was found to vary with both temperature and salinity. As a result, it was determined that Ba:Ca profiles in statoliths have the potential to help resolve jellyfish movements in some circumstances. The use of elemental chemistry to elucidate horizontal or vertical movements of cubozoan species has significant potential and application.