We steamed for just over four hours until we reached our first dive site at approximately 3,000 meters (almost two miles). The first few hours of the dive were spent filling the Midwater Respirometry System (MRS) sample buckets with mysid shrimp for a deep deployment. According to Research Specialist Kim Reisenbichler the shrimp are “good guinea pigs” because they are common at this depth and give reliable respiration results.

Chief ROV Pilot Knute Brekke hung the MRS on a cable at a depth of 2895 meters. The instrument includes eight sample buckets, six contain shrimp and two are kept as controls. We will leave the equipment hanging at depth for 48 hours then come back to retrieve it. During the experiment period Kim will remotely adjust the pH (acidity) of the water in the chambers and measure the reaction of the mysids. These efforts help the researchers understand how the animals will respond to future conditions as the ocean shifts in acidity.

We found hitchhikers! As we explored with the ROV we observed a pycnogonid spider living parasitically on a midwater jelly (Pandea rubra) at 700 meters. Although we have seen this before, it was still a surprising sight because pycnogonids are typically spotted on the seafloor and we were a very long distance (over 2,000 meters) off the bottom. We also filmed the large and unusual medusa Deepstaria reticulum with a parasitic isopod, Anuropus, tucked inside.