Research in the Cariaco Basin: 10 Years and Growing

From left to right: USC researchers deploy a sediment trap; the Venezuelan
research vessel B/0 Hermano Gines; Ramon Varela, Mary Scranton (MSRC),
Gordon Taylor (MSRC), Frank Muller-Karger, and Javier Gutierez

MSRC professors Mary Scranton and Gordon Taylor, with their students Xueju Lin (Ph.D. student) and Dane Percy (M.S. student), are heading to Venezuela on Thursday to conduct their twenty-first sampling cruise in the Cariaco Basin on the northern continental shelf of Venezuela. What makes this particular expedition Wlique is the addition of two new Microbial Observatory projects, building on the CARIACO time series that began in 1995. Their 10-day field campaign includes three days at sea collecting water, chemical and microbiological samples that, Taylor explained, “will undoubtedly uncover new genetic cliversity and perhaps primitive taxa among prokatyotes and micro-eukaryotes in this pennanently anoxic ecosystem.”

The first new project is a collaborative effort with Andrei Chistoserdov at the University of Louisiana at Lafayette. Over the next three years, they will search for new genetic diversity among prokatyotes focusing on
Archaea and Bacteria domains. “The core interest,” Scranton noted, .. is the composition of the microbial community and how it is controlled by the chemistry of the basin.” To do this, Taylor added, “We will be harvesting prokaryotic DNA and conducting phylogenetic stuclies (16S rDNA libraries, FISH, etc.) as they relate to geochemical processes.”

The second new project is a five-year effort with as many collaborators – Slava Epstein at Northeastern University, MSRC ‘s Gordon Taylor, Stefan Sievert and Virginia Edgcomb from Woods Hole Oceanographic
Institution, and David Patterson at the University of Sydney in Australia. Taylor explained that the goal of this project is to “uncover ctyptic diversity within marine protozoa, specifically anaerobic protozoa. Preliminary results have already led to some very tantalizing evolutionary and ecological hypotheses.” This project combines cutting-edge molecular techniques with classical morphometric-based taxonomy. Both projects are funded through NSF’s Microbial Observatories Program.

Scranton and Taylor have conducted research in the Cariaco Basin for at least a decade. In November 1995, they teamed up with Frank MOller-Karger at the University of South Florida and Robert Thunell at the University of South Carolina to become the founding principal investigators (P.I.s) of the CARIACO (Carbon Retention in a Colored Ocean) Program. Today this international collaboration between Venezuela and the United States includes eight institutions, 10 P .I.s, and dozens of students, technicians and support staff. Scranton noted, “This program has been a very positive example of a gent~ine collaboration. The dedication of the Venezuelan team is absolutely key and essential to the success of the project …

The CARIACO Program conducts monthly cruises to the Cariaco Basin and examines the hydrography, nutrient chemistry, carbon dynamics, primary productivity and microbial biomass. Last month marked the 107th consecutive, successfully completed, time series analysis at the same station. Noteworthy results of this work include: seeing the influence of E1 Nino – a largely Pacific phenomenon – in the Caribbean, both in terms of productivity and the sedimentary record; and recording the effects of local earthquakes on sedimentation and the redistribution of sediments. Perhaps the most significant finding is that this site is a net source of CO2 to the atmosphere rather than a sink – despite seasonal upwelling and high productivity.

For more information, see the CARIACO web site at http://www.imars.usf.edu/CAR/index.html, or