Deep midwater respirometry system (MRS) deployment
November 9, 2013
Overnight we transited to the deep MRS site (see yesterday’s post and the cruise background for an introduction to the MRS). This site has a mooring in much deeper water than yesterday’s site, about 3,000 meters. This mooring has hangers where we can deploy the MRS at multiple depths. The goal today was to collect deep-living animals (between 2,550 and 2,800 meters), hang the MRS on the 2,800-meter hanger, and measure the animals’ respiration for two days.
The ROV quickly descended to 2,500 meters where we starting looking for animals large enough to measure their respiration in the MRS. Very small animals will not make any detectable changes in the oxygen content of the water in the sampler. There are eight chambers in the MRS and we collected four mysids (deep-sea shrimp-like animals) and two jellies called Poralia rufescens. The last two chambers were left without animals as controls for the experiment. Measuring the oxygen in the control will let Kim Reisenbichler know if anything went wrong with the experiment. Large changes in the control indicate a malfunction.
People often think that nothing lives that deep in the ocean, but I can assure you there are plenty of interesting animals down there. After we deployed the MRS, we had the rest of the day to search for target species. We have a long list of animals that are of interest to the science team and their collaborators. Here are a few of the fascinating and rare animals we came across today:
—Susan von Thun