Role of winds and tides in timing of beach strandings, occurrence, and significance of swarms of the jellyfish Crambione mastigophora Mass 1903 (Scyphozoa: Rhizostomeae: Catostylidae) in north-western Australia

Very large swarms of the red jellyfish Crambione mastigophora in north-western Australia disrupt swimming on tourist beaches causing economic impacts. In October 2012, jellyfish stranding on Cable Beach (density 2.20 ± 0.43 ind. m⁻²) was estimated at 52.8 million individuals or 14,172 t wet weight along 15 km of beach. Reports of strandings after this period and up to 250 km south of this location indicate even larger swarm biomass. Strandings of jellyfish were significantly associated with a 2-day lag in conditions of small tidal ranges (<5 m). More than 90% of strandings occurred 2 days after winds were blowing onshore, but with the small number of days when satellite wind data were available during the study period, this result was not statistically significant. Dedicated instrument measurements of meteorological parameters, rather than the indirect measures used in this study (satellite winds and modelled currents) may improve the predictability of such events and help authorities to plan for and manage swimming activity on beaches. We also show a high incidence of predation by C. mastigophora on bivalve larvae which may have a significant impact on the reproductive output of pearl oyster broodstock in the region.