Monday, March 19, 2012

Trophic BATS: Post # 8 (Day 6)

Chief Scientist Tammi Richardson looks on from the bridge deck during the sediment trap recovery.

Early this morning, we arrived at our third and final station. Our comparison site, which is outside of the cyclonic eddy, also happens to be the site of the Bermuda Atlantic Time-series Study (BATS). BATS is quite useful to have as a comparison site as the time-series provides researchers reference data for physical, chemical, and biological parameters. Long-term time series, like BATS (monthly sampling began in 1988) are incredibly important in understanding the process of ocean biogeochemical cycling on seasonal to decadal time-scales. Observations from time-series allow projects like Trophic BATS to fuel more in depth research on the complexity of the open ocean ecosystem.

As a whole, Trophic BATS is a single research project, however, there are many individual components that are projects of themselves, especially to the graduate students participating on this cruise.

Out of the University of Rhode Island, Matt Baumann and Brenden Mackinson are paired up with the BIOS squad. Matt’s project isn’t directly related to Trophic BATS, but he has previously worked with the group on the Bering Sea Ecosystem Study, and will be conducting thorium measurements from the water column and sediment traps.

Also, Matt and Brenden operate the in-situ pumps that have the ability to filter hundreds of liters of seawater from a specific depth. From the collected filter, re-suspended particulate will be analyzed for POC, pigments, and potentially DNA. The in-situ pumps also have the ability to size fractionate filtered water, which is an additional compliment for the team’s questions surrounding the importance of small cells in primary production and contribution to export. Brenden’s project will partially focus on Trophic BATS and investigating the role of small cells in carbon export.

Matt and Brenden anxiously await the return of their in-situ pump.

Bridget Bachman leads the primary productivity measurements. As a graduate student with Tammi Richardson at South Carolina, her project will investigate size-fractionated primary production and taxon specific production. To obtain taxon-specific production, the flow cytometer (and Stacey!) will sort Bridget’s samples into multiple groups: prochlorococchus, synechococchus, and pico-eukaryotes. Using this sorting technique, she will be able to determine production per group, per cell, and their growth rates. Ultimately, Bridget will be tying these measurements, along with the entirety of measurements made by each research team during Trophic BATS into an ecosystem model. The model will hope to be used as an estimate for quantifying the flow of carbon between specific trophic levels (using rates measured from our research cruises) and carbon export – all dependent on food web community structure.

Bridget and Francesca imitate hurling bottles at the Production/Grazing array at superhuman speeds. Both of them pursued oceanography from their true passion, filtering.

All for today!

Doug Bell
Research Technician, Bermuda Institute of Ocean Sciences

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