Field Program

Understanding What We Do

The CARIACO program was established in November 1995 through sponsorship of the National Science Foundation (NSF) and Venezuela’s Fondo Nacional de Ciencia, Tecnología e Innovación (FONACIT). This long tern ocean time series joint effort has involved five major Venezuelan institutions and three universities in the U.S. The infrastructure is also a contribution to the International Geosphere-Biosphere Programme (IGBP), Land-Ocean Interactions in the Coastal Zone Program (LOICZ).

Monthly oceanographic cruises to the CARIACO station (10.5° N, 64.67° W) have been conducted since November 1995 to examine the hydrography, primary production, and settling flux of particulate material. We use the 75-foot R/V Hermano Gines of the Fundación La Salle de Ciencias Naturales (FLASA) located on Margarita Island, Venezuela. Water is collected using a rosette ensemble equipped with twelve 8-lt. bottles and a CTD (conductivity-temperature-depth meter); the CTD also has an oxygen sensor, a fluorometer for chlorophyll-a estimates, and a transmissometer. Data are read out real-time on a computer screen on board the ship as we lower the rosette ensemble to approximately 1,380 m, the bottom of the Cariaco Basin. Water samples are analyzed for various parameters including phytoplankton biomass, dissolved and particulate nutrient and carbon concentration, and primary productivity rates. We also measure total bacterial production. Winds are measured at Santiago Mariño airport (10.9°N 63.96°W) and at the Meteorological station of La Salle (10.54°N, 64.06°W, height 3m).

The data collected through the CARIACO ocean time series project is available freely through this web page and through the Ocean Carbon and Biogeochemistry (OCB) Data Management Office (DMO) at WHOI (http://ocb.whoi.edu/cariaco.html). Data and description of the CARIACO program is also available in Spanish at http://cariaco.intecmar.usb.ve/

To measure the flux of settling particles, we use five automated sediment traps placed at 150, 225, 410, 810, and 1210 m on a mooring. These funnel-shaped traps are synchronized to collect samples over 2 week periods into a series of jars. The traps are retrieved and re-deployed every 6 months (May and November), and samples are used to estimate carbonate, organic carbon, nitrogen, and biogenic silica fluxes and various other geochemical parameters.

To measure currents at the CARIACO ocean time series station, we use a Lowered Acoustic Doppler Current Profiler (LADCP) which is deployed during each monthly cruise. The LADCP profiles the water column between 0 and 400m; below 400m there is not enough backscatter to produce a good signal (Virmani and Weisberg, 2009).

More information on the methods used in the time-series program can be found in the CARIACO methods manual pdf and in our methods section.