Report of Activities on the RV Ron Brown CMarZ Cruise 06-03
10 - 12 April 2006

This is the first report of the CMarZ cruise aboard the Research Vessel Ronald H. Brown and is designated RB06-03. The focus of the CMarZ program is on the development of a taxonomically comprehensive assessment of biodiversity of animal plankton throughout the world ocean. The project goal is to produce accurate and complete information on zooplankton species diversity, biomass, biogeographical distribution, genetic diversity, and community structure by 2010. Our taxonomic focus is the animals that drift with ocean currents throughout their lives (i.e., the holozooplankton). This assemblage currently includes ~6,800 described species in fifteen phyla; our expectation is that at least that many new species will be discovered as a result of our efforts. This effort is proposed in association with the Census of Marine Zooplankton (CMarZ), an ocean realm field project of the Census of Marine Life (CoML).

On this cruise, the focus is the tropical/subtropical waters of the Atlantic Ocean west of the mid-Atlantic ridge. We are out to collect and identify the zooplankton distributed throughout the entire water column, with a particular focus on the under-sampled mesopelagic, bathypelagic, abyssopelagic zones. The scientific participants on this cruise include CMarZ researchers, expert taxonomists, staff, and students. Sampling is going to be conducted along a transect extending from the northern Sargasso Sea to the equatorial waters east of Brazil. At five primary stations, environmental data and zooplankton samples will be collected using three Multiple Opening/Closing Nets and Environmental Sensing Systems (MOCNESS). One is a large opening/closing trawl and two are smaller multiple net systems, with several mesh sizes. Other samples are being collected with ring nets and water bottles, and by blue water SCUBA diving.

Samples are being analyzed at sea using traditional taxonomic approaches and molecular systematic analysis, including DNA sequencing of a target gene portion for each species. Protocols for molecular analysis of bulk zooplankton samples will be tested while at sea. After the cruise, follow-up molecular analysis, species counts, and expert taxonomic evaluation and description of any putative new or undescribed species will be done in association with the CMarZ Taxonomic Network. In addition to the intensive sampling of the water column, a series of lectures and workshops will be conducted as part of the at-sea training in zooplankton morphological and molecular systematic approaches.

The cruise got underway at 1400 on 10 April when we left the port of Charleston, South Carolina after four days intense set up of the equipment and laboratory spaces needed for the work at sea. Shortly after leaving the dock, the ship spent time in the sound while a calibration of the Roberson Navigation system took place, which had undergone repairs while the ship was in port.

We finally left the sound and got underway for the first station located in the Northern Sargasso Sea about 1800. During the early hours of the night of the 10th, the ship’s ride was comfortable, but the winds picked up to around 20 kts towards the morning of the 11th as we steamed out across the continental shelf and the Gulf Stream, and the motion of the vessel made many of the scientific party a bit seasick. The moderately rough weather continued into daylight on the 11th of April and the loading of nets onto to the three Multiple Opening/Closing Nets and Environmental Sensing Systems (MOCNESS) and other work in the laboratories went slowly. The initial abandon ship and the fire and boat drill took place around 1030.

Problems with the operation of the trawl winch with 0.68" conducting cable, which is the mainstay of our sampling program, had been identified a couple of weeks before the start of the cruise and most of the repairs had taken place by the time the ship left the dock. On the evening of the 11th, 8000 meters of trawl wire was streamed to test the ability of the winch to carry out the deep MOCNESS tows. Although the winch had no difficulty in paying the cable out, there was significant difficulty bringing the wire back on board at a reasonable haul in speed. During the test, a load cell burned out and it was replaced. A second test took place on the evening of the 12th. This test indicated that the winch could be used to tow the MOCNESS trawl to bathy and abyssopelagic depths.

Several science meetings took place during the steaming to Station 1. On the evening of the 11th, there was an introductory meeting to discuss the cruise objectives and to review plans for work at the stations. On the afternoon of the 12th there were two additional meetings. The first was to work out the final details of the sampling at a station and the protocols for how each of the zooplankton samples were to be processed. The second involved a number of the officers and crew and was focused on the methods of deployment of the over-the-side equipment and who would be in charge of coordinating them.

During the afternoon of the 11th, a ½ m diameter ring net was deployed to 100 m to provide a collection of zooplankton that could be used by the taxonomic experts on board to begin their work on this cruise. A number of species of copepods, ostracods, gelatinous animals, formaminfera, and other groups were picked live from the sample and many of these were identified. Some of these were then selected for genetic sequencing on the 12th. Earlier in this day, a first occurred when a zooplankton species (a copepod, Disseta grandis, caught on a previous cruise) was sequenced at sea. As far as we know, this is the first time a gene sequencer has produced a gene sequence at sea. This is a very significant early milestone for this cruise.

Peter Wiebe
Chief Scientist