Thursday, July 9, 2015

The longest day

After leaving port yesterday, it only took us about 12 hours to reach our first station. The habitats we're sampling in this cruise are located on the continental margin, so they're relatively close to land. There was a short multibeam survey of the seafloor once we got the station, and then our first gear deployment immediately after. Not even a full day at sea, and we already had gear in the water. Freaky fast!

Caitlin strikes a power stance while
waiting to deploy the MOCNESS.
The first gear deployment was a MOCNESS tow, which is our main sampling gear. MOCNESS stands for Multiple Opening and Closing Net Environmental Sampling System, and it's basically a series of giant nets. We lower it down into the water column with one net open (only one net is open at a time), then open and close the nets in series on the way back up. That way, we get plankton samples from different depths in the water column, all cleanly separated in their respective nets. The ultimate goal is to sort, preserve, and identify all of the larvae we find in the plankton samples to be able to tell how different species of larvae are distributed in the water column. Maybe some species send their larvae to the surface to disperse in faster currents. Maybe some species of larvae stay near the bottom so they have a better chance of finding suitable habitat. No matter what the larval strategy is, it's our job to figure it out.

Deploying the MOCNESS is tricky business, because we have to make sure none of the 10 nets get tangled on their way into the water. It took four of us on deck, plus two crew members, to get it straight. Hopefully, we'll get better with practice as the cruise goes on. After the nets were safely in the water, most of us went to sleep, but two stayed awake to monitor the net on its journey to the deep. We had to be vigilant about watching the on-screen displays, checking the angle of the wire, the velocity of the net, the speed of the ship, the payout of the winch. I'll give you more details later, but suffice it to say we were on high alert all night.

Kara and Laurel analyzing a larva in the lab.
When the MOCNESS came to the surface in the morning, 3 more members of our team woke up and helped with recovery. We carefully brought all 10 nets on deck without getting them tangled (thank goodness!), brought our samples into the lab, and started sorting. The two of us that stayed up overnight went down for a nap while everyone else settled in at their microscopes. It took us from about 6 am until 5 pm to sort the entire sample, and that's with 7 people working on at least a semi-consistent basis. So. Many. Larvae.

The beginning of this cruise has been a whirlwind so far, and it feels like the past 36 hours all belonged to one extraordinarily long day. Of course, I've been awake for most of them. (Don't worry; I'll sleep after I'm done writing.) I think our first MOCNESS tow went surprisingly well, all things considered. None of the seven of us on board are particularly experienced with the MOCNESS, and the grad student who was responsible for our gear in the past isn't on this cruise. We've been able to figure it out between our fragmented recollections and help from the ship's personnel, but I definitely look forward to smoothing out the rough spots in our process as the cruise goes on.

We survived our first deployment and our first long day at sea. It can only get better from here!

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