Rapid, Long-Distance Dispersal by Pumice Rafting.

Pumice is an extremely effective rafting agent that can dramatically increase the dispersal range of a variety of marine organisms and connect isolated shallow marine and coastal ecosystems. Here we report on a significant recent pumice rafting and long-distance dispersal event that occurred across the southwest Pacific following the 2006 explosive eruption of Home Reef Volcano in Tonga. We have constrained the trajectory, and rate, biomass and biodiversity of transfer, discovering more than 80 species and a substantial biomass underwent a .5000 km journey in 7–8 months. Differing microenvironmental conditions on the pumice, caused by relative stability of clasts at the sea surface, promoted diversity in biotic recruitment. Our findings emphasise pumice rafting as an important process facilitating the distribution of marine life, which have implications for colonisation processes and success, the management of sensitive marine environments, and invasive pest species.

Figure 2: Trajectory map of the 2006–2007 pumice rafts, based on the integrated surface velocity field. Pumice strandings following the Home Reef (HR) eruption were reported at the following locations: Fiji (,33 days); Vanuatu (VA, 88 days); New Caledonia (NC, ,115 days); Willis Island (WI, ,180 days); Lizard Island (LI, ,200 days); Mackay (MA, ,250 days); Broadbeach (BR, ,250 days). Other abbreviations: LB, Lau Basin; NZ, New Zealand; PNG, Papua New Guinea; MR, Marion Reef; LM, Lady Musgrave Reef; WH, Whitsunday Island; BA, Ballina. Brown shaded region along northeastern Australia is the Great Barrier Reef World Heritage Area. Grey areas without bathymetric information represent continental shelves of ,1000 m depth, where geostrophic ocean currents were not calculated. An animated version of the pumice raft trajectory is provided in Supporting Information (Figure S1) to this paper.