Text and images by Natalie Cohen
During October 2014, the Marchetti lab from The University of North Carolina at Chapel Hill participated on a research cruise in collaboration with GSC and USFQ with the aim of characterizing the phytoplankton community that surrounds the Galapagos Islands. The goal of this project is to begin a long-term survey of the area and to track changes in the phytoplankton community over time, which would allow scientists to tie observed changes in the macrofauna to changes in their food source.
Onboard the R/V Guadalupe River, chemical, physical and biological measurements were taken to survey the surface water. These measurements included standing stock biomass, primary productivity, nitrate uptake rates, nutrient concentrations, bacterial and phytoplankton cell counts, light intensity in the water column, temperature, salinity, and turbidity to name a few!
In order to ensure the scientists had adequate working space for collecting measurements on the ship, a gigantic garden shed was assembled and secured on the deck! In the shed, filtration units and supplies were arranged to facilitate quick water sampling. At around 7am each morning the Captain steamed out to deep water, where a CTD (instrument for obtaining physical parameters) was sent down to 90 meters and collected data every 0.25 second. After bringing the CTD back up and calculating which depth corresponded to desired light levels, niskin collection bottles were sent down to capture seawater. On deck, water was filtered for about 4 hours and preservations were performed. This was a huge effort and couldn’t have been completed without the assistance of the Galapagos National Park and GSC.
There are several useful implications of this research, one being discovering the connection between phytoplankton populations and catastrophic El Nino events. During El Nino years when Galapagos animals such as marine iguanas suffer population loss, do we see a noticeable difference in the phytoplankton assemblages? Can we predict these events before they occur by tracking phytoplankton and physical water properties? If so, could we potentially reduce ecosystem damage caused during these catastrophic events?