Biogeochemical responses to changes in climate and ocean circulation
Principal Investigator: Francisco Chavez
Co-investigators: Dan Davis, Gernot Friederich, Robert Herlien, Russell Hopcroft, Hans Jannasch, Ken Johnson, Raphael Kudela, Mary Silver, Peter Strutton
Growing concern over global climate change, whether natural or human-caused, has focused increased attention on the need to understand ocean-related processes that vary over time and space. Research on the relationships between climate, ocean circulation, the abundance of marine plants and animals, and the cycling of organic materials and chemical elements has been a primary focus at MBARI since its founding. The strategy pursued by institute scientists in Monterey Bay and the waters off Central California has included three main elements. First, on frequent shipboard surveys since 1989, researchers have measured a wide range of ocean properties, amassing the most comprehensive ocean time series known for a coastal region. Second, MBARIs moorings, equipped with a suite of sophisticated instruments and sensors, have provided continuous data to complement shipboard records. Third, a growing stream of satellite information particularly on sea-surface temperature and ocean color, which reveals areas of high phytoplankton productionis adding valuable detail to the biogeochemical picture.
In 1998 the Project 1 team will enhance and expand the use of the MBARI Ocean Observing System (MOOS) assets. Mooring, satellite, and shipboard monitoring will continue, with Monterey Bay time-series cruises every three weeks on the R/V Point Lobos. Additional cruises on the R/V Western Flyer will span areas of coastal upwelling and low-nutrient waters, from the coast to several hundred kilometers offshore. These multi-discipline surveys are expected to provide crucial information to institute researchers mapping the distribution of nutrients and deciphering the dynamics of phytoplankton production and algal blooms. Among other topics researchers will investigate are the natural cycles of carbon and nitrogen and the concentration in regional waters of fossil-fuel- derived carbon dioxide, which is drawn down from the atmosphere.
MBARI researchers and collaborators are working on new technology that will assist these studies. Devices to protect in-water instruments from biological fouling are being built and tested. The mooring group is also considering the development of an above-water spectroradiometer, which measures light reflected from the surfaceinformation that is used in deriving estimations of phytoplankton biomass and production from satellite data. Another device under development is a submersible chemical analyzer that would employ solenoid-powered pumps to obtain rapid readings on chemical concentrations and could either be towed up and down the water column or installed on a mooring. Also on the drawing board is an improved electronic controller for continuous data transmission from the moorings to shore. Development of a new OASIS (Ocean Acquisition System for Interdisciplinary Science) controller is dependent on the work of the technology infrastructure group (see Project 11) and will likely evolve over a number of years.
The onset of the 1997 El Niņo has provided an unprecedented opportunity for documenting the little understood biogeochemical consequences of such events in the waters off Central California. Occurring every five to 10 years, El Niņo events are major disrupters of marine ecosystems and patterns of heat distribution in the ocean. The regional effects from this ocean warmingin particular the impacts on the distribution of nutrients, phytoplankton, and zooplanktonare expected to peak in the spring and summer of 1998, after which abnormally cool conditions are forecasted. This will offer MBARI researchers the chance to monitor, over a two-year period, opposing extreme conditions in terms of productivity. The results are expected to give a quantum boost to the scientific understanding of El Niņo and contribute to future efforts to model the processes involved.
To carry out the El Niņo component of Project 1, an additional surface mooring (M3) will be deployed about 150 km from shore, at a site where oceanographic conditions vary significantly. Two subsurface moorings with instruments will also be deployed. Measurements from current meters, devices that trap sediments accumulating on the seafloor, and other instruments and their counterparts on M1 and M2 will reveal ecological changes at these key locations. This will allow researchers to test hypotheses about El Niņos impacts on upwelling and nutrient availability, changes in horizontal currents and local winds, and other consequences.
MBARIs range of research sites are representative of many coastal and open ocean areas, making the institutes scientific findings applicable world-wide. The El Niņo studies, along with the broader Project 1 agenda may well reap significant benefits for the world ocean community.
Last updated: 07 October 2004