Past Research Projects

Using free vehicle benthic flux chambers (landers), sediment corers and Niskin bottles, Moss Landing and USC scientists study the exchange of metals, nutrients and oxygen between sediments and water along coastal California. Some of the largest fluxes occur in highly productive areas, such as Monterey Bay, where biological material sinks to the sea floor and is regenerated. Other large fluxes, more chemically controlled, occur in semi-isolated basins off Southern California where bottom water has been depleted of oxygen and metals become solubilized. Many of our graduate students have thesis projects as part of this study. Our MEQ projects are similar but focus on more impacted areas.

Using a submersible analyzer (scanner), Moss Landing and NOAA scientists study the chemical and physical properties of hydrothermal vent plumes emanating from the Juan de Fuca vent system off the coast of Washington. These are warm buoyant plumes containing high levels of iron and manganese due to reactions between seawater and the earths crust at very high temperatures. Iron quickly precipitates out and returns to the surrounding sediments whereas manganese, which is slower to precipitate, is transported much further from the vent source. These and other elements support the existence of biological communities that originate from chemical energy rather than energy from sunlight. Similar communities have been discovered near "cold seeps" in Monterey Bay.

IronEx I, 1993

IronEx II, 1995

Sequential additions of solubilized iron to a patch of water in the Equatorial Pacific produced an enormous phytoplankton bloom. Grazing pressure by zooplankton was also monitored. Interestingly, zooplankton did not perform typical vertical migration behavior. Instead they remained with the patch/bloom to feed both day and night. The results unequivocally demonstrate that iron availability limits productivity in some areas of the worlds oceans.

This lab, formerly under the guidance of Dr. John Martin, is one of the few labs in the world that can accurately collect and measure the low levels of trace metals in the ocean. Trace element distributions have been measured all over the world. They have participated in large, long term studies such as VERTEX and JGOFS which examine the processes that determine how elements are cycled throughout the oceans. They have most recently played a large role in the IronEX studies. The trace metal group was most recently on a cruise in the Southern Ocean around Antarctica determining iron and and nutrient distributions and examining the feasibility of a Southern Ocean iron fertilization experiment.