I have just returned from 40 days at sea aboard the NOAA Ship Ronald H. Brown as a participant in the fourth Gulf of Mexico Ecosystems and Carbon Cruise (GOMECC-4). This cruise was organized by chief scientists working at NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML) in Miami, FL, but included researchers from around the world working at institutions throughout the United States and Mexico. These scientists were collecting samples and data to answer questions about the carbon cycle and ocean acidification in the Gulf of Mexico as well as about the open water ecosystems throughout the Gulf by collecting data along transect lines running from shallow coastal sites to deep offshore sites. In total, the Brown travelled over 5000 nautical miles sampling throughout American and Mexican waters-the Brown actually became the first research vessel to be given permission to work in Mexican national waters since Mexico’s Covid 19 precautions were put into place. I was a member of the science crew with an official position as a “CTD watch stander”, as well as collecting data for my own research during the cruise.
As CTD watch stander, my job was to supervise the deployment of the Conductivity, Temperature, and Depth (CTD) instrument. This instrument had sensors that allowed real time sensing of the salinity (measured by differences in conductivity), temperature, depth (as a function of water pressure), dissolved oxygen, and chlorophyll concentration, an Acoustic Doppler Current Profiler (ADCP) that measures current speed using sound, and 24 Niskin bottles that can be triggered to collect water from different depths in the water column. Deploying the CTD could be a long process, depending on water depth- some sites were over 3500 meters deep, and winching it to the seafloor and back up again at those sites could take over 3 hours. When it returned to the boat, water samples would be collected from the Niskin bottles by members of the science crew and analyzed for chemical parameters relevant to understanding the carbon system, including temperature, dissolved oxygen, pH, dissolved inorganic carbon, total alkalinity, and CO2 content, measurements more relevant to understanding the whole ecosystem, such as salinity and dissolved nutrients, and the use of cutting edge environmental DNA methods to identify organisms living in the water by the DNA they leave behind in the seawater.
My primary motivation for joining such a long cruise was the opportunity to work directly with one of my NOAA mentors, Dr. Emily Osborne, who was sailing with the cruise to deploy automated biogeochemical sensing floats and to take sediment core samples. As a postdoctoral researcher with the NOAA Center for Coastal and Marine Ecosystems, I will be spending at least 6 months as a researcher at AOML working with Drs. Emily Osborne and Luke Thompson, learning how to employ genetic sequencing methods to create genetic “barcodes” that can be used to identify the presence of abundant Gulf of Mexico planktonic foraminiferal species commonly used in paleoclimate applications. This work will help enhance the accuracy of environmental DNA analyses in the Gulf, which are currently missing barcodes for these widespread species, and as these species are commonly used in paleoclimate applications, this work will also play a foundational role in adapting eDNA approaches to the study of the paleoclimate record. On this cruise, I collected planktonic foraminifera from plankton net tows being performed to assess the planktonic community and will use these samples during my residency at AOML in 2022. I also assisted Dr. Osborne in the collection of sediment cores using an 8-core gravity multi corer, collecting cores to be used as part of the same project as my genetic work as well as cores for my own future research in conjunction with colleagues at FAMU.
More details available at: bit.ly/bjross