Spires of sulfur
Deep-sea vents unlike most others, in a seafloor crater in the Antarctic, with spires of sulfur spewing sulfuric acid, and a "dead zone" of deceased shrimp and squid - yet life finds a way.
The inhabitants of "Kemp Caldera" are revealed in our research paper out this week, so here's some background about the discovery.
These vents are at 1.4 km deep on the slopes of a small undersea volcano, which is itself in an undersea crater (the "Kemp Caldera"), next to an undersea mountain ("Kemp Seamount"), at the southern end of the South Sandwich Islands in the Antarctic.
In 2009 Rob Larter of the British Antarctic Survey led the first of our NERC ChEsSo (Chemosynthetic Ecosystems of the Southern Ocean" expeditions, aboard the RRS James Clark Ross, during which we discovered a seafloor caldera next to Kemp Seamount.
The satellite-derived map of the area suggested fairly featureless seafloor around the seamount, but more detailed mapping by our ship's sonar revealed a caldera (fancy word for a crater-like feature, but not a volcano or impact crater), 4 km across and 1.6 km (about a mile) deep.
(I love this: where on Earth can you find a feature 4 km across and 1.6 km high/deep that no-one knew was there before? In the deep ocean, that's where).
On the 2009 expedition, geochemist (and "Vent-Finder-General") Doug Connelly of the National Oceanography Centre lowered instruments into the caldera and found warmer water inside it, indicating hydrothermal vents there. We towed a camera but didn't intercept the vents on that trip.
One year later, in January-February 2010, we were back on our next ChEsSo expedition, led by Alex Rogers aboard the RRS James Cook, with the UK's deep-diving ROV (Remotely Operated Vehicle).
We sent the ROV into the caldera, and in one of the most exciting ROV dives that I've experienced, we found the vents on the small volcanic cone at its heart. And those vents were different to the "black smoker" vents that we discovered on the nearby East Scotia Ridge.
By way of a bonus, during one of the ROV dives in the caldera we also stumbled across a whale skeleton on the ocean floor - the first "whale-fall" in the Antarctic to be studied in situ (by Diva Amon during her PhD).
The Kemp Caldera is an exciting place; this week's paper is an initial plunge into its biology, but there's more to come...
Jon Copley, November 2019
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