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Bioluminescence Expedition – Log 3

Darrin Schultz and Alex Lapides deploy the trawl net from the back deck of the Western Flyer.

Bioluminescence Expedition – Log 3

When the Haddock lab is at sea, we use different technologies to explore and collect the many interesting species we hope to study. The main tool is MBARI’s underwater robot, the remotely operated vehicle ROV Doc Ricketts. The Doc Ricketts has cameras, lights, two manipulator

Steve Haddock and Shannon Johnson unload sampling containers from the ROV Doc Ricketts after a successful dive. Photo by Lynne Christianson

arms and sampling chambers that the ROV pilots and scientists operate from a control room on the ship. With the ROV, we can explore and sample delicate organisms in the water column or seafloor, all the way down to 4,000 meters (2.5 miles). The pilots are extremely adept at adding and refining sampling capabilities to this flexible workhorse, giving it incredible ability to capture tiny and delicate ctenophores and other gelatinous zooplankton. Yesterday, using this vehicle the size of a minivan, we caught a ctenophore about the size of a pomegranate seed.

Using our low-light camera on the ROV, we can even image bioluminescence from organisms in the wild in full color—something that couldn’t even be imagined even five years ago.

Another method we use is blue-water scuba diving. Blue-water diving is like an underwater space-walk, and allows us to collect shallow organisms in the upper 25 meters (80 feet). Divers are tethered to a central line and drift among the plankton (and the occasional shark, sea lion, or ocean sunfish). Organisms are collected by hand into jars and brought back to the ship’s lab. So far on this expedition it has been too windy for the divers to get in the water, but we have been able to get in full ROV dives to keep everyone very busy in the lab.

Darrin Schultz and Alex Lapides deploy the trawl net from the back deck of the Western Flyer. Photo by Shannon Johnson.

Midwater trawling is the traditional method of collecting samples, which we also use on our expeditions. The trawl net can capture a broad size range of organisms, from tiny copepods to jellies and small fish, so trawling then gives us a record of the diversity at particular depths. However, many delicate organisms, such as the ctenophores we are interested in, are damaged on collection, so the trawl is best for more sturdy organisms, and the ROV remains the best way to retrieve delicate jellies in perfect condition.

This tiny ctenophore was collected by the ROV Doc Ricketts. Photo by Steve Haddock