The U.S. GEOTRACES North Atlantic zonal section cruise was scheduled for 15 October through 5 December 2010. Because of a major irresolvable mechanical failure of the ship's propulsion system, the expedition had to be terminated in the Cape Verde Islands on 4 November after completing about one third of the planned track. This required on-the-spot changes in return travel for all sea-going investigators as well as in shipping arrangements for all their samples and equipment. The funds requested in this proposal address the PI's need to cover a graduate student, travel, and supplies costs associated with his participation in the continuation of the North Atlantic section cruise scheduled for autumn 2011. Graduate student and travel support are needed to ensure a student at the University of Southern California can participate in the conclusion of the cruise and collect samples to finish his dissertation. Additional travel costs are included to demobilize the ship at the end of the cruise. Funds for supplies replace those lost during the initial leg of the cruise. At the end of this project, the relationship between Cu cycling and its speciation over a wide range of oceanographic regimes will be documents, as well as the influence of this element on the community structure of Prochlorococcus at the eco-type level.
Copper is generally thought of as a metal solid, but it is most commonly found in nature in a dissolved ionic form. It is essential for all life on earth, mainly because it is a critical component in many enzymes. It is found throughout the oceans, and in some places it is very high (where it can be toxic) or very low, (where it can actually impede processes catalyzed by the aforementioned enzymes). On the GEOTRACES Atlantic Section, the distribution of copper was investigated, as well as its chemical and biological reactivity. The data revealed that copper was scarce, with small, residual amounts that are tightly bound by some currently unknown substances. This makes the acquisition of copper quite a challenge, even for tiny organisms like bacteria. Surprisingly, this was true even in the deep ocean and close to the bottom. But biologically available copper was scarcest of all in places where there was a lot of biological activity - for instance off the African coast. Under those conditions, copper might impede some important biochemical reactions, and tip the balance in favor of certain organisms over others. It is planned to use the findings of this project to develop a model to determine how copper behaves throughout the oceans, and how it might change in a warmer ocean. A big part of that effort will involve comparing the data with data for other elements, like iron to learn how their distinctly different chemistries and biochemistries contribute to the differences in their behavior in the ocean.
