Mesocosms with varying treatments. From left to right: full strength oil and Corexit, diluted oil and Corexit, oil, control.

ADDOMExers recently gathered on the campus of Texas A&M Universities at Galveston. The purpose of this meeting was to test drive the large tanks (mesocosms) that will be used to house microbial (bacterial and plankton) communities while studying how oil and dispersants affect their growth and the formation of aggregates. To do this, four mesocosms were filled with seawater and inoculated with plankton from the Gulf. Mesocosms were treated with oil and oil plus dispersant.


Post-doc Shawn Doyle adds an inoculum of plankton and bacteria taken from the docks of Texas A&M University at Galveston to mesocosms.

Over about a week, ADDOMEx team members followed changes in both the biology and chemistry. The inoculated microbial communities were allowed to grow and depending on conditions, form aggregates. Subsamples of the water and the aggregates were taken every 8 to 24 hours for several days. These subsamples are currently being analyzed by different members of the ADDOMEx team with hopes to present findings at the upcoming GOMRI meeting in Tampa Florida. The activity was amazingly informative.  Not only will the results be instrumental in directing future experimentation but the samples collected during this meeting will be extremely helpful for fine tuning the various protocols that will be used presently and in the future. Dealing with “contamination” from the oil and dispersant has proved to be in some cases an unexpected additional challenge to what had previously been routine protocols.

In addition to lots of experimentation, ADDOMEx teams collaborated to calibrate several fluorometers (Horiba, Perkin-Elmer, Shimadzu and Turner) that they will use to measure the concentration of oil in their samples. This will ensure consistency in measurements over the course of experimentation and importantly between team members spread across the country. Along with the original team members, newly hired postdoc’s, grad students as well as high school students and summer interns joined the fun!