Collecting squids and the oxygen minimum zone
March 25, 2013
Today we had two dives. The first was for collections. We collected quite a few squids, including two Octopoteuthis deletron, which Alicia Bitondo and Chris Payne will try to keep happy and healthy in the ship’s cold room. As mentioned in an earlier post, the Monterey Bay Aquarium is interested in displaying deep-sea squids in their upcoming cephalopod exhibit. In order to keep deep-sea animals alive, they have to be kept in the dark, with water at temperatures and oxygen levels similar to their natural habitat. Chris spends lots of time “bubbling” seawater. He is adding nitrogen to the water to deplete the oxygen levels. When the oxygen levels are in a good range for the squids, he can use that water to give them new, fresh water that they will hopefully thrive in.
On the second dive of the day, the ROV descended quickly down to 2,700 meters (8,800 feet), the depth at which we deployed the Midwater Respirometry System (MRS) yesterday. The MRS gathers oxygen consumption measurements in situ to gauge the metabolism of animals without subjecting them to the stresses of decompression during transport to the surface. The deep mysids that we collected with the MRS yesterday wouldn’t survive the trip up to the surface for study in the lab, so this technology is critical to learning about their physiology.
As the climate changes and ocean temperatures warm, an area of the midwater called the oxygen minimum zone (OMZ) is expanding. Data provided by the MRS helps to determine the oxygen level at which each species is forced to compensate for oxygen levels lower than optimal. Once these oxygen levels are known for a number of species, the future of how expansion of the OMZ will change the composition of the midwater community can be predicted, as well as the ecological implications of such changes.
—Susan von Thun