Detached Seaweeds as Important Dispersal Agents Across the Southern Ocean

Abstract

After detachment from their substratum, many seaweeds can float or drift at the mercy of currents and winds, thereby facilitating their dispersal and connectivity. In Antarctica only one species possess floating structures (gas-filled vesicles), the brown seaweed Cystosphaera jacquinotti. However, other species such as Durvillaea antarctica and Macrocystis pyrifera that form abundant forests around the sub-Antarctic islands can also remain at the sea surface once detached, providing a potential dispersal mechanism not only for the seaweeds but also for the associated biota. Additionally, recent reports indicate that floating D. antarctica can reach the Antarctic continent from sub-Antarctic regions. Herein, we collect information about floating and drifting seaweeds in Antarctica, but also their biology, physiology, and distribution within the sub-Antarctic sources. Up to now, only a few species have been recorded floating in Antarctica, and mainly during the first Antartic explorations. So far, most of the studies on detached seaweeds only highlight their importance, when already stranded and serving as carbon sources for benthic communities. However, some seaweed species are able to handle present sea surface conditions in Antarctica and thus in the future when higher temperatures, less ice and more available substrate are available, they might be able to frequently travel and colonize this region, thereby representing an important dispersal mode.