The Briny Deep - a post by Kristie Cobb Hacke

Yesterday morning on a tour of the bridge of the Steward Johnson following the deployment of the submersible, we had the opportunity to chat with some of the sub crew and a pilot. During our chat they were sharing stories of other dives. One in particular was incredibly interesting to me because it continues the idea of worlds within worlds (the sneeze theory). Craig Caddigan was mentioning that he piloted the submersible to a location in the Gulf of Mexico that contained an “underwater lake.” The lake was a dense brine pool, made up of water with an incredibly high density due to salinity and found at over 2000 feet depth. Craig described landing the sub on the lack and bouncing along the surface and creating ripples. The brine area has its own waves and “beach”, in this case surrounded by a 10’ ring of mussels. The mussels use methane as their primary food source. The submersible was unable to descend into the brine lake because it was too dense, but they did take along some tools that could sample the contents.

A brine pool in the Gulf of Mexico

What is amazing to me is that this brine sea is contained within the ocean. Do the animals that live around this area know that they are living in a sea within a larger ocean? When I sit on the beach am I merely sitting on the edge of a pool within someone else’s greater ocean. Am I at risk of being someone else’s sample? These big thinking questions are what keep me going but the scientists aboard the Abrolhos are focused on the small things that make up the ocean. Right now they are collecting small coral samples, sediment, rock, fish and other items. During the cruise other members of the HBOI staff have been creating maps so that the scientists can use them for future trips or they can clearly note the location of sample and sediment collections. The CTD collected water at the same locations where the submersible was deployed, so that bacteria and viruses can be measured and identified in the water column. The hope is that each of these small pieces can create a larger overall understanding of the structure and biology of the Abrolhos reef.