Raft of pumice floats past Low
A HUGE floating raft of pumice, teeming with marine hitchhikers has travelled more than 4000 kilometres and was spotted off the coast of Low Isles recently.
The pumice was created by an underwater volcanic eruption near New Zealand and has been travelling for around 12 months. Rafts of porous volcanic rock are remarkable, but poorly understood, natural phenomenon which play a unique role in transporting marine species across oceans.
The floating island of pumice is thought to have travelled more than 4000 kilometres across the Tasman and the Coral Sea before being spotted off Low Isles, by Low Isles caretaker Wayne Fox.
‘‘On Thursday 21st, we noticed a lot of pumice washing up on the beach and saw it was coming from a 600 square metre raft, sitting about two nautical miles away from Low Isles,’’ Wayne said.
‘‘It was unusual for so much pumice to wash up on the shore. Some of the pieces were quite big, about the size of a human head, and I hadn’t seen anything like it before.
‘‘On closer inspection you could see the pieces of pumice had become home to a vast amount of marine life.
‘‘It was spectacular to see it, it has travelled so far and so quickly. ‘‘It was truly unique.’’ Dr Scott Bryan, a world expert in pumice rafts from the Queensland University of Technology, said the pumice was the result of an eruption by the Havre Seamount in July 2012 in the Kermadac Islands, north of New Zealand.
The underwater volcano spewed out a large amount of pumice, creating a raft estimated to be more than 20,000 square kilometres in size.
‘‘Pumice rafts are the only process in evolutionary history that can transport species fairly rapidly up to 30 kilometres per day across deep oceans that would normally act as geographic barriers,’’ Dr Bryan said.
‘‘Species such as goose and acorn barnacles, molluscs, ane- mones, bristle worms, hydroids and crabs are just some of the creatures floating on this volcanic rock. In the past we’ve seen rafts become home to micro communities of more than 80 species including corals, and sometimes the weight of the hitchhikers is so great it sinks the pumice.’’
The raft had previously been spotted south-east Queensland, northern New South Wales before making its way to Heron Island and eventually into Far North waters.
While pumice can float for many years, it can also accumulate on beaches or sink after becoming waterlogged or overloaded with different species.
WASHED UP: eruption
Wayne Fox with pumice from New Zealand underwater volcanic