Julia Sweet and Chris Brown collect treated water for use in the roller tables.

Just before Christmas, ADDOMEx members from Texas A&M University at Galveston (TAMUG), as well as Mount Allison University in Canada travelled to Santa Barbara, CA to participate in a lab exchange. Dr. Uta Passow and her lab manager Julia Sweet from the University of California Santa Barbara (UCSB) hosted this exchange in an effort to streamline the protocols that are used by the consortium when forming aggregates in roller tables.

Roller tables have been used for some time by Dr. Passow to form and study aggregates. These tables function by slowly spinning circular tanks that have been completely filled with water. The speed of the rolling tank (and the lack of air bubbles inside) is such that solid body rotation is established and the aggregates in the tank are moved up with the body of water while they sink, effectively keeping them from falling out of suspension.


A roller tank with visible aggregates inside.

“I was fascinated by both the approach and the way the experiment unfolded.” Says Chris Brown, a participating researcher from Mt. Allison, “The roller tank design allows aggregates to continually sink, grow and change, simulating an extended sinking event from the upper ocean to the depths.”

Sinking aggregates (such as those pictured at right) are important for bringing nutrients from the surface of the ocean to its depths; they can also collect oil droplets from a spill as they sink, potentially exposing the droplets to oil degrading micro-organisms.

 “This experiment broadened my exposure to diatom ecology research.” He says, “I look forward to seeing the molecular level data on the algal gene expression as well as the response of the bacterial community.”

Another benefit of the lab-exchange was that it allowed the researchers to discuss differences in the functionality of the roller tables that are used at different research institutions. This was particularly helpful for Cameron Jackson, an undergrad from TAMUG who accompanied the group.  Cameron has been primarily responsible for the design and construction of the roller tables at the A&M campus.

“For example, at UCSB the roller table is designed like a bookcase with multiple shelves at varying heights, while at TAMUG the roller tables have been designed to be a single long continuous shelf,” says Alicia Williams from TAMUG.

“Because the tanks can “walk” or move along the rolling components if not properly balanced or limited in some way, discussing potential options to prevent this problem given our different set-ups was invaluable.”

Additionally, the lab exchange fostered better communication and collaboration within the ADDOMEx teams. “The exchange of information was by no means one-sided,” Alicia continues, “I was involved in the measurement of fluorescence associated with the water accommodated fraction of oil during the experiment, which I have done extensively at TAMUG. By actively doing this with host lab team members, we were able to discuss problems and solutions we had both encountered, ultimately coming up with standard practices to be applied together in the future.”


The roller table system housed at University of California Santa Barbara in Dr. Uta Passow’s lab. The samples were incubated in the dark to simulate sinking through the deep ocean where there is very little light.

Julia Sweet was particularly happy with the results, “The Passow Lab benefited immensely from the manpower and expertise of our visitors. Having a visiting team of energetic and competent scientists allowed us to complete an experiment which would have been impossible to attempt without assistance.”

Following such a successful week of experimentation, ADDOMEx team members would definitely recommend a similar lab exchange to other research groups.

Jennifer Genzer, a research assistant from TAMUG states “I can’t imagine a better way of trading knowledge among a group of scientists. Exchanging protocols is one thing, but having the chance to discuss different methods and to appreciate how key the timing is of a roller tank experiment, is another. We gained invaluable tricks of the trade from visiting the wonderful Passow Lab that I don’t believe we could have learned any other way.”

Additionally, samples from this experiment were shipped to the other ADDOMEx teams across the United States for further analysis. Analyses of the aggregates included understanding the chemical and community composition, phytoplankton physiology, oil concentrations, etc., and findings were presented at the Gulf of Mexico Oil Spill Ecosystem Conference in Tampa, Florida.