RV Yuzhmorgeologiya

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RV Yuzhmorgeologiya

 

The RV Yuzhmorgeologiya at the dock in Punta Arenas, Chile before the start of the 2006 cruise.
The RV Yuzhmorgeologiya at the dock in Punta Arenas, Chile before the start of the 2006 cruise.

The “Yuzhmo” (as we affectionately refer to the ship) is our main research platform for this project, as well as our home for the duration of the 6 week cruise. It is an ice-strengthened ship, ~ 300 ft. long, that was originally used for geophysical oceanography research in the USSR. This year (2006) is the ship’s 20th anniversary. The ship and crew are Russian which means a lot of signs in Cyrillic around the boat and that we regularly have borscht for lunch. In addition to being one of the most stable platforms to work on, this ship contains one of the (if not THE) friendliest crew in the oceans. The AMLR program has chartered the Yuzhmo for many years so many of the crew have become a part of the AMLR family.

Multiple Frequency Acoustics

The Yuzhmo has four hull-mounted acoustic echosounders operating at 38, 70, 120, and 200 kHz. Tony Cossio and Dr. Christian Reiss are in charge of monitoring and processing the acoustic data, as well as calibrating the echosounders before each cruise (a process that involves metal spheres, 4 small motors, and a LOT of fishing line). With the echosounders we can see scattering layers or patches in the water column down to 500 m. By comparing how much acoustic energy a patch scatters at the different frequencies, the acoustic system can be used to distinguish copepods from small fish from krill. The acoustic system provides a high resolution 2-D picture of the ocean interior as we proceed on our survey track. However, when using any acoustic system to obtain information about biological creatures it is necessary to ground-truth (or sea-truth in our case) the data with other means of sampling the biology.

Zooplankton Net Sampling and Identification

Cassandra and Darci work up a net tow by counting and identifying the different zooplankton caught by the net. (Photo by Darci).
Cassandra and Darci work up a net tow by counting and identifying the different zooplankton caught by the net. (Photo by Darci).

The “Zoo van” on board the Yuzhmo contains several dissecting microscopes, lots of petri dishes and tupperware containers, numerous zooplankton identification books and manuals, and (most importantly) Dr. Valerie Loeb and a team of 7 zooplanktoneers. At each station during the survey, an Isaacs-Kidd Midwater Trawl (IKMT) is lowered to 170 m (or the bottom whichever is shallower) and brought back up to the surface.  What is truly remarkable about the Zoo van team is that the samples are processed (identified and enumerated) on board the ship, so that when we walk off the boat in Punta Arenas, we have all the zooplankton data in hand. This is a great advantage over preserving the samples and then processing them back in the lab.

Physical Oceanographic Measurements

The CTD rosette being launched off the ship.
The CTD rosette being launched off the ship.

Derek Needham and Marcel van den Berg are in charge of the hydrographic measurements on board the Yuzhmo. They have been with the AMLR program for many years and provide a Southern Hemisphere view (they’re both from South Africa) for the rest of us from the other side of the world. At each station during the survey, they conduct a CTD cast which collects measurements of conductivity, temperature, depth (pressure), fluorescence, dissolved oxygen, several other parameters, and water samples from different depths. These data allow us to identify water masses (bodies of water that have similar physical properties) and determine some water movement (upwelling, downwelling, mixing).

Bird and Mammal Observations

The Bird Hut for observations of predators on the flying bridge of the ship.
The Bird Hut for observations of predators on the flying bridge of the ship.

Jarrod Santora and Mike Force are responsible for monitoring and recording the distribution and behavior of sea birds and marine mammals during the survey. They work their shifts from the new Bird Hut on the flying bridge of the Yuzhmo where they have a great vantage point for monitoring the animals that depend on the krill for their food needs. As we are studying an ecosystem (and not just the krill population), their data are essential to understanding the interactions between prey and predators in the marine environment.

Phytoplankton Measurements

One of the factors that affects the distribution and abundance of krill is the availability of their food source, phytoplankton. Chris Hewes is responsible for analyzing the water samples that are brought up in the CTD casts and assessing the amount of phytoplankton that are found in the water column. When one combines this information with the hydrographic data, we get a better idea of what the ecosystem is doing on a “bottom-up” basis. Additional data sets such as ocean color images from satellites passing over the area can complement the shipboard observations.