This morning started out as another early one, with Dr. Jim McManus, Dr. Will Berelson, Chris Moser, and Bill Fanning using the ship’s depth finder to determine a suitable spot for deploying the Lander at its 7th site. They found favorable conditions at around 154 meters’ depth. Once the spot was chosen, and breakfast was had, it was off and running on a day full of sampling. The Lander was deployed first, followed by the Multicore, a CTD cast, GO-Flos, and lastly the In-Situ pumps. They pumps were ran at their three different depths for 3 hours, and then were pulled before we headed off in search of new waters with familiar features.
Still no activity on our Redox experiment, once things get going in there, we will post lab activities so you can try to recreate what we are trying out here. The plankton tows, however, have been great! The Captain even helped out so we could do a late night tow off the continental shelf, and see who was coming up from the depths in their nightly migration. We have found many different types of copepods, salps, enchinoderm larvae, as well as various species of dinoflagellates, Trichodesmium, and phytoplankton. For each tow, we are keeping track of the time, location, depth, as well as the most recent CTD cast for that location. Try your hand at some plankton math, and see if you’ve got what it takes to calculate the abundance of each planktonic critter in a cubic meter of sea water!
Right before dinner, we began a new set of CTD recon deployments. This time we are looking for a particle maximum that appears roughly between 100 and 300 meters down. At this point in time, we do not have a definitive answer as to what is causing these maximums, nor do we have exact and widely mapped locations to draw connections with. All we have to go on are the CTDs already conducted that show it appearing in deeper waters, but not to the west of one of our last stations; it stays to the east. It seems that it is flowing in finger-like projections off of the continental shelf. Hopefully tonight we will find a substantial particle maximum in the water column where we can get some good samples. From there, it may be able to be determined if the particles are from Iron Oxide being released from the soil as a chemical occurrence, and precipitating back down, or if it is a physical event that is bringing the Iron up out of the sediments. Further investigations could show if there are even different isotope configurations in these particle maximum samples.
The last CTD we deployed showed no real evidence of this particle maximum on the plot created during the CTD cast. So the decision was made to return an hour back the way we came, to try again at an earlier sampling site to find the presence of those particles. Dr. Silke Severmann brought up the point that many people think of the water as just one mass. It is, however, comprised of layers; layers caused by salinity, temperature, freshwater events, currents, weather events, and even chemical changes. Just because you find a perfectly clean patch of salt water measuring 35 ppt (average amount of dissolved salt particles per thousand parts of water) one night does not mean you will wake up to exactly the same parameters the next morning. The ubiquitous nature of the ocean keeps scientists looking for patterns, and following theories. Sometimes it comes down to trial and error until the money spot is found, which takes perseverance and keen insight; just another illustration of the dedication this group of scientists possess, and a reminder this field is not anywhere near a “nine-to-five” type career.
This time next Friday, we will be looking back at all of the things we learned, experienced, and witnessed and wonder where the time went! These past two weeks have been eye-opening to this particular, particulate world of oceanography, and I can say with certain confidence our teaching will never be the same…and I mean that in the best possible way. Until then, though, what could be a more serene way to spend your Friday night, than sampling by moonlight?