Determining picoplankton community and abundance near Hawaiian Islands with varying human and nutrient impacts
The objective of this study is to assess the difference in the picoplankton community in waters off islands with varying human impacts. The picoplankton community around Hawaii accounts for 70% of chlorophyll a in local surface waters (Chen 2008). Three of types of picoplankton found in the waters around Hawaii are, Prochlorococcus, Synechococcus, and picoeukaryotes (Campbell 1993). Oligotrophic oceans are dominated by picoplankton because they are small cells that require less nutrients to grow than larger phytoplankton (Ringuet 2005). However, humans have greatly impacted the Hawaiian Islands. Rivers near cultivated land have high concentrations of dissolved inorganic nitrogen and soluble reactive phosphorus (Boehm 2010). Nutrient runoff creates phytoplankton blooms in oligotrophic oceans (Ringuet 2005). Understanding the change in the picoplankton community due to human impacts is vital since picoplankton play an important role in carbon sequestration and the transfer of energy up trophic levesl (Campbell 1993). The hypothesis for this study expects different picoplankton community off heavily impacted islands versus those that are low impacted. To measure this the SeaFlow, an in-situ flow cytometer, will quantify cells based on light scatter as a proxy for size and chlorophyll pigment by autofluorescence (Millan-Nunez 2010). The SeaFlow will take continuous water sample at surface waters from the flow through system on the R/V Thomas G. Thompson. Samples from a CTD cast, will be sent to Kathy Krogslund’s lab, to determine nutrient concentrations. Samples will be taken off the coast of several Hawaiian islands and from the open ocean onboard the ship during December 27th- January 4th. Advisors on this study are François Ribalet, for help with the biological analysis and Jarred Swalwell, the engineer of the SeaFlow.