Remote and isolated ecosystems in the Southern Ocean and Antarctica have been thought to be relatively protected from invasive species carried in ballast water due to the strong circumpolar winds and currents. A new study, however, finds evidence of a non-anthropogenic mechanism for introduction to the continent.
Seventy million kelp rafts are estimated to be afloat in the Southern Ocean at any one time. Making its way onto an Antarctic beach inside the flooded caldera of a small, relatively warm volcanic island—Deception Island—one such raft was found by researchers to carry "hitch-hiking" passenger organisms, including the non-native and ecologically harmful bryozoan Membranipora membranacea.
Using GBIF-mediated occurrences, the authors mapped the distributions of the passenger species found on kelp rafts at Deception Island to assess the potential of these species for becoming established. M. membranacea is found as far north as northern Scandinavia in the Arctic, where other studies have found algal substrate may be more important than temperature in limiting its spread. With widespread macroalgal substrates, the risk of invasion in the Southern Ocean may be high.