Two of the scientists that I just went on the shelf hypoxia cruise with, Nancy Rabalais (who was also the Chief Scientist) and Gene Turner, and their colleagues have published an aggregate report of 26 years of shelf hypoxia research in ES&T (see link above). They also develop a statistical model based on the data, which even takes into account things like variations in sampling methodology over the years. The model is part of how the estimates for future hypoxia are made.
After a stormy morning of sampling back in the D’ and C lines, we arrived safely back in sunny Cocodrie yesterday about 14:30. The Pelican was cleared out within a couple hours, and the crew got to work turning her around for another cruise leaving today. The extent of hypoxia was lower than predicted, but nevertheless one of the larger areas on record. See the press release for more info. Overall, a very successful trip. For us microbiologists, most of the work lies ahead. First will be extensive DNA/RNA sequencing, then microbial community analysis, metagenomics/transcriptomics, and single cell genomics. All of this will be correlated with the extensive biogeochemical data collected by not only Lauren and I, but the whole team. Our results will be here in the future, so stay tuned.
We found the western end if the hypoxic zone along the K and S transects last night and are returning eastward. Most of the day will be spent transiting. A low pressure system kicked up the seas a little last night, and it’s been a bit sloppy this morning, but easing. We are going to return to a few stations for microbial sampling (took samples again on the J line in a bit of a squall), and we need to pick up additional box cores as well.
Tactical- the western side of our station map
The geographic expansion of hypoxia along our westward transit continues. We had to go all the way to the most southern station of the I line, I9, before reaching a zone without bottom hypoxia. Today we are transiting back north along the J line and will reach K. In keeping with Nancy’s commitment to science communication, particularly with the lay public, she and Leslie are creating and maintaining a real-time map of bottom DO concentrations here. It’s fascinating to watch this develop. The vertical profiles that come off the CTD are the most exciting parts of the day, and we frequently make bets now as to how low the O2 will be and at what depth. Gene Turner usually wins the bets. He and Nancy have developed a sixth sense for the distribution of hypoxia after this many years of study.
It’s generally been a beautiful cruise. The full moon a few nights ago was breathtaking as it peaked in and out of the clouds. At night the oil platforms dot the horizon line like low-lying stars. The night shift has seen crabs at the surface, particularly in the areas of bottom hypoxia. There’s also a lot of Sargassum sea weed in the Gulf. I’m used to seeing it in the Sargasso Sea, but I had no idea it grew here. Of course a quick search shows that it grows all over the world and there are many different species. We’ve also seen dolphins, birds, fish and I noticed a giant comb jelly near some Sargassum yesterday afternoon.
A little down time for an update. We are in transit to the I line after finishing H this morning. We are continuing to find expanding bottom hypoxia as we move westward. Nancy and Leslie are creating maps of the hypoxia as we go. Lauren and I are sampling both inside and outside the hypoxic zones. We’re tag teaming on opposite shifts and doing between 6-8 stations per day.
No cruise goes off without a hitch. Crises overcome thus far: winch needing to be re-spooled, CTD switched off the original winch and then back, hydraulic line break (they use vegetable-based biodegradable hydraulic fluid on the Pelican- very cool), main floor drain clogging. But onward we go. The crew has done a great job responding to these issues.
Three more full sampling days to go. Seas are staying calm, 10-15 kt winds, it’s cloudy this morning. Looks like we’ll be back before Tropical Storm Dorian (the storm formerly known as tropical depression four) gets to the area, which is nice.
Finished the E line during the night. Still have calm seas and good weather. Keeping our eye on newly formed tropical depression four. Sampling the F line this morning. Noticing increased bottom hypoxia as we move west.