Quantifying movement of the tropical Australian cubozoan Chironex fleckeri using acoustic telemetry

Abstract

Cubomedusae are considered to have superior swimming abilities compared to other pelagic cnidarians, yet many of the theories describing such behaviours are based on anecdotal evidence, sting records or opportunistic sightings, rather than quantitative data. Acoustic telemetry was used to document the movements of adult Chironex fleckeri medusae within both coastal and estuarine habitats. The rate at which tagged medusae moved was influenced by an interaction between time period (day or night) and habitat (coastal or estuarine), with rates of travel being relatively similar during the day and night within the coastal habitat, but significantly greater at night than during the day within the estuarine habitat. Medusae in coastal habitats travelled at similar rates throughout all tidal states while estuarine medusae travelled at significantly faster rates towards the middle of the tide than at the low and high ebbs. Such movements occurred with, and independent of, tidally generated currents, but at increased current speeds, medusae tended to travel with the current. Data are also presented that show that large medusae may move from coastal to estuarine habitats.