The Pumpers

Today we are completing the 4^th of 5 “super” stations, with 10 total stations remaining before we go to Tahiti.

Last week at station 22, we had a short power outage on the ship. Growing up in California during the 1990s energy debacle, I have grown used to blackouts on land. Here on the ship, it was a bit different. Sure, the lights weren’t on and none of the science equipment was usable, but the ship engines also lost power. When on station, the ship uses a considerable amount of energy to face into the waves and wind (which makes for a smoother ride). Without power, we veered towards the starboard side and things got a bit rough in the “trough” – the low point between waves. Instead of a gentle forward/aft rocking this is a much sharper port/starboard rocking.

As a result of veering to the starboard instead of the port, we “ran over” the wire that was currently deployed at 3,200 m with all 8 of the McLane pumps attached. With over $100,000 hanging on the line, you can imagine how stressful it was to watch helplessly as the ship’s side rocked and rubbed at the wire. Luckily, the wire held and the engineers managed to get power restored within a few minutes. Sadly, that’s all the time it took to damage the wire to the point that it can’t be trusted for use any further, so the 8 pumps were hauled back on board and the wire was cut off at the damaged spot. That’s around $30,000 of wire that was trimmed, so not an easy cut to make.

The captain (front left), and 3 ABs (Brian, back left; Michele, back right; Jason, front right) coiling the wire.

This is what ~3,000 m of wire looks like, coiled on our deck. Imagine uncoiling it and hanging it straight down – and that’s not even the deepest we go in the ocean! Previous stations have gone as deep at 5,000 m, and our typical depth on this side of the ridge is 4,000 m.

What exactly are these McLane pumps and what do they do?

These pumps manage to pull ~1,800 liters of water [each] across filters the size of a dessert plate. That’s the equivalent of 15,000+ sticks of melted butter! These filters have much smaller holes than a coffee filter, so it takes a strong force to get water across them.

From left to right: Spike (WHOI), Dan (WHOI/BIGELOW), and Sara (U. Minn) recover a pump and Niskin with water in it.

The deployment of these pumps takes ~1.5 hours to get them into place on deep casts (45 minutes on shallower ones), 3 hours to pump the water, and about the same time to recover as deploy. Once back on deck, Dan take the filters into a clean lab and photographs them, slices them up for the various groups who need them for analysis, and dries them to preserve them for tests back on land. The “bits” on the filters are analyzed for more elements on the periodic table than I can list here. If you can think of it, they probably measure it!

Dan pulls the filters out of their holders.

Why filter water?

These filters are used to collect “suspended particulate matter” in the water. By “suspended particulate matter” we mean small plankton, fecal pellets [excrement], and sediments in the water. These “bits” are so small you can’t see them individually without a microscope. When a bunch of these bits are on a filter together, they are much easier to see. For example, the white filters on the left in the photo are from deeper waters without much in them; the green filters on the right are from the surface where photosynthetic plankton live. Phytoplankton are the plants of our ocean and function similarly in the ocean as terrestrial plants do on land.

Filters left to dry in a clean hood.

Along with the particles, 30 liters of water is collected from each of the same depths. This is for researchers who want to study the differences between elements that are dissolved in the water versus stuck on to the “bits” in the water. Here, Erin and Virginie lift one of these very heavy (~150 lb) Niskin bottles into place for sampling. Erin is a Ph.D. student and one of the things she is looking at is thorium which helps tell us how long the “bits” are in the water; Virginie is also a Ph.D. student at LEGOS in France and she’s measuring radium for similar reasons.

Erin (WHOI, left) and Virginie (LEGOS, right) lift the heavy Niskin into place.

In other news, all our casts have been catching baby man-o-wars lately. Man-o-wars are known for their painful sting when you touch them, although the baby ones aren’t supposed to be as bad. I’m too chicken to actually find out for myself, so instead I got a (blurry) photo of one dangling from our GoFlo yesterday. They’re a beautiful dark blue color – just like the water!

Baby man-o-war; the float was the size of a quarter in diameter and had a ~4 foot long tail.