Shelfwide Hypoxia Cruise 2017

Recently, I’ve been lucky enough to take part in Dr. Nancy Rabalais’ annual mapping of the hypoxic zone in the Gulf of Mexico. Dr. Rabalais has led this cruise for the past 31 years, and has graciously allowed me onboard the R/V Pelican for my first research cruise. This cruise set out July 31st and returned on August 1st.

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The R/V Pelican in dock at LUMCON before departure.

My primary role was to collect surface water at each site that will be used by the Rabalais Lab for water nutrient and suspended sediment data. This consisted of throwing the infamous bucket overboard:

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Water collection with the surface bucket.

While onboard, I also was able to collect some samples for the Thrash Lab. I sampled from stations nearshore on transects that extended outward from our Board of Regents coastal sites that we have been visiting for the past few years (check out Henson et al. 2016 for more info). I collected surface water via the CTD from sites of interest and used a peristaltic pump to size fraction the water through 2.7um and 0.2um filters. These filters will be used to study the community composition of sites offshore in relation to the three year data that we already have from our coastal sites.

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My filtering set-up in one of the labs onboard. The seas were mostly calm, so I was able to only lightly strap my materials.
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LSU Research Assistant Tom (left) and LSU undergraduate Ethan (right) casting the CTD. Notice the lovely view at midnight.

The first day of the cruise was a bumpy ride, and I was a little seasick despite the motion sickness medicine. Gladly, the waves soon settled, and the rest of the cruise was smooth sailing! I was on the night shift (7pm-7am), which meant that we got to see all of the cool fauna! The floodlight that followed the CTD into the water was a beacon for sealife, and we saw jellyfish, eels, squid, dolphins, crabs, and fish off all kinds. The fauna actually became an indicator of the dissolved oxygen in the bottom waters. Often when we found crabs and eels swimming on the surface, the bottom waters had very low oxygen levels or were virtually anoxic. While we waited for the CTD to come back onboard, we sometimes netted some Sargassum to see what kind of critters were living there.

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Cute fish that we pulled from the Sargassum (we threw it back).

One of my favorite parts about the trip was the spectacular views of the sky. At night on the shelf, the only lights come from oil rigs. Sometimes we were quite close to these rigs…

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Oil rig next to our C6C sampling site. It was really neat to see one this close.
…while other times we were pretty far from their light pollution. When we found ourselves distanced from the rigs, the stars lit up the sky, and the Milky Way was visible from the bow of the ship. We often laid there gazing upwards and talking about our lives and how the open sky humbled our problems. I didn’t have a camera capable of imaging the night sky, but I did get some shots of the sunrises and sunsets that we witnessed:
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Sunset from the bow of the boat.
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Probably the most vivid sunset of the trip.
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Sunrise from the work deck.
Overall, this was both a great sampling trip and an amazing life experience. I bonded with the science and boat crew, and learned so much from Dr. Rabalais, Dr. Turner, and Wendy. I am thankful for this opportunity, and eager to be at sea again.
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The highly fashionable safety gear required on the work deck.
Check out https://gulfhypoxia.net for participants, daily logs, images, site maps, and results of this cruise (spoiler: the hypoxic zone this year is record breaking!), and follow me @vclanclos on twitter!
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