It’s about 5 am central time, we’re on our last transect of this cruise, Neil Young is ‘Rockin’ in the Free World’, and the Late-Night watch is feeling contemplative. As we turned the corner and deployed the CTD for our last transect, the seas laid down to a gentle roll for the final push. The data are still coming in, and we’re continuing to see some interesting patterns in the oxygen and CDOM – multiple layers of low oxygen that correspond to the fluorescence signals. The Mini-OPC is cranking along, churning out plankton patterns that also seem to have some correspondence with the physical features, but the details will have to wait for the post-cruise processing on dry land. Our water-catchers, who have been sampling the smallest organisms, including bacteria and micro-plankton, have almost exhausted their supply of sample vials, just in the nick of time. Upper trophic level sampling – meaning fish – has taken a break due to bad weather that interfered with the acoustic signals used to identify fish targets in the water column. The companion vessel that was shadowing us and trawling for fish had headed for home after filling their freezer and suffering through a long night of rough seas.
That’s where we’re at, but the work is not done yet. We’ll finish up the transect after day break, secure the gear on deck and begin our transit home. On the way back to Cocodrie, LA, we’ll start to pack up the labs and prepare our stuff for shipment back to Corvallis, OR, Cambridge, MD, Akron, OH, Dauphin Island, AL, Baton Rouge, LA, and Ann Arbor, MI. Once we hit the protection of Terrebonne Bay, we’ll have to calibrate the fish acoustics gear. This entails dangling two different tungsten carbide spheres from a fishing rod as standard targets for the acoustics instruments. In other words, the metal balls act as fake fish with known size and weight. After running the instrument with the simulated fish hanging below it, the operator can go back through the collected data and determine the density of fish at any given time and depth.
All in all it has been quite an eventful cruise. The OPC has been rebuilt twice and replaced once. The TAPS (a high frequency acoustic instrument used to measure zooplankton abundance) was fixed on day one as well. The 15 year old Scanfish tow cable, tired and frayed after so many years of service, had to be mended. The fisheries acoustics on the other hand, was brand-spanking new at the beginning of the cruise and had a successful shakedown after working out some kinks on the first couple of days. One other casualty, besides the OPC which is still here, is the ship’s gaff, which was lost at sea while retrieving the Scanfish in rough weather. ‘Twas a good gaff too, and will be sorely missed.
Much of our success would not have been possible without the experience and expertise of the RV Pelican crew. They have had a very busy summer, thanks in large part to the flurry of activity around the oil spill, but were nonetheless always ready to make sure the science happened. And we were well fed. Very well fed. Some highlights included sushi (!), carrot cake, tiramisu, eggs benedict, egg rolls, gumbo, and various baked goods, all homemade. Oscar Wilde once said something like, ‘The only difference between going to sea and prison is the added risk of drowning’, but I think the food probably elevates research cruising even more.
Speaking of food, it’s almost breakfast time. I wonder what we’ll have this morning?