Life on the Ocean Floor: Antarctic Ocean Hydrothermal Vent Exploration

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Octopus near Antarctic hydrothermal vent: Image courtesy of Professor Alex Rogers

Interview with Professor Alex Rogers

Decoded Science had the opportunity to ask Professor Rogers a few questions about this research.

Decoded Science: What do you consider the most significant discovery that came of this project?

Professor Rogers: “The discovery of an entirely new type of hydrothermal vent community strikingly different from anything we have seen before. Vents elsewhere are dominated by other animals, for example tube worms (Pacific), swarms of shrimps (Atlantic, Indian Ocean), mussels (Atlantic, Pacific, Indian Ocean), stalked barnacles (western Pacific). Our vents were visually dominated by a new species of yeti crab that occurred at huge densities (600 per meter squared), dense clumps of stalked barnacles, anemones and a large snail. Also, unusually, one of the main vent predators appeared to be a stichasterid sea star (with 7 arms). Analysis of the composition of the East Scotia vents indicates that they are distinct from those elsewhere, although they seem to share some affinity with those in the southern and western Pacific. Overall the finding of such a distinctive community indicates that our understanding of the distribution and evolution of vent fauna globally to date is limited.

Vent organisms thrive in the unusual environment of hydrothermal vents: Image courtesy of Professor Alex Rogers

Another highly significant discovery was what was not found at the Southern Ocean vents. We found no mussels, no vent crabs, no tube worms, no vent shrimp. One of the reasons we wishes to undertake this work was to test the hypothesis that the Southern Ocean acted as a dispersal gateway from one ocean to another (e.g. Atlantic to Indian Ocean and Pacific to Atlantic and Indian Ocean) as suggested by the presence of a fauna with mixed affinities at the Central Indian Ocean vents discovered in the early 2000s.

The lack of these “typical” vent groups suggests that whilst the Southern Ocean may act as a dispersal gateway for some species, it is a barrier to others. Decapod crabs and lobsters, for example may not be able to regulate magnesium in their bodies at low temperatures and effectively shut down and die. Many of the other groups not present on the East Scotia Ridge have a feeding larval stage as part of their life history. This occurs with relatively low prevalence in Antarctic marine invertebrates as they favour larvae with their own food stores, perhaps to cope with the extreme seasonality of Antarctic waters. Thus the reason for absence of some of the groups we did not find is that their life history prevents them from becoming established in Antarctic waters.”

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