|Office: Hawaii Loa Campus, AC 242A
Phone: (808) 356-5231
David B. Field, Ph.D.
Associate Professor of Marine Sciences
- Ph.D., Oceanography, Scripps Institution of Oceanography (UCSD) 2004
- B.S., Biology (Ecology, Behavior, and Evolution) University of California, San Diego 1995
Minor: Spanish Literature
- OAP Universidad Arturo Prat, Iquique, Chile; (Opportunities Abroad Program) 1994
- BIOL 3002 General Oceanography II
- BIOL 3003 General Oceanography II Lab
- BIOL 3081 Ecology Laboratory
- MARS 4070 Chemical Oceanography
- MARS 4210 Marine Fisheries and Management
- MARS 6020 Marine Science Field Methods
- MARS 6070 Chemical Oceanography
- MARS 6910 Current Topic in Marine Science
- NSCI 6120 Graduate Seminar II - Thesis Presentation
- NSCI 6900 Master's Research
- NSCI 7000 Master's Thesis
Global change, decadal-to millennial-scale variability, paleoceanography, geobiology, sedimentary processes, geochemical tracers, fisheries oceanography, plankton ecology
An overarching interest is to understand natural variability in ocean climate and marine ecosystems and distinguish natural variability from anthropogenic effects on ocean systems. Such work is done by linking knowledge of ocean processes observed in modern records with historical observations and geological archives, and thus spans both ecological and geological timescales and processes. I have largely worked with fossils within marine sedimentary records but aim to work with fossil and living corals.
Much of my investigations of past climate changes have been done with sediment cores from laminated sediments. Sediments accumulating in extremely low oxygen environments, such as the Santa Barbara Basin, are not exposed to benthic organisms that usually mix and bioturbate ocean sediments. Thus sediment from disoxic environments preserve seasonal or annual differences in sediment type, which provides very high-resolution records within the sediments. Fossil plankton within the sediments, such as foraminifera, diatoms, coccolithophorids, etc., as well as their isotopic signatures reveal changes in water temperature and ocean climate. There are many other geochemical approaches to inferring past changes as well.
In order to interpret these records from marine sediments I have also examined how environmental factors affect the abundance and distribution of living foramininfera by taking plankton tows across the California Current.
Another fossil found within ocean sediments are fish remains, scales, bones, and otoliths, of very abundant pelagic fishes like sardines and anchovies. By quantifying the changes in abundance of fish scales in different layers of ocean sediments, we can infer past changes in population sizes prior to the onset of industrial fishing. We also fish scale records with other paleo records, historical records of fish catch, guano harvest, or archived shipboard measurements of Sea surface temperature and/or wind speed to understand how pelagic fish populations respond to environmental changes over long timescales.
Another tool for inferring some of the potential mechanisms responsible for variability in fish populations is to examine their isotopic signatures of δ15N and δ13C. I have measured δ15N and δ13C on tissues of living sardines in the California Current as well as making measurements from sardines raised in laboratory setting of controlled temperatures and on different diets to understand how isotopic signatures are acquired in scales and muscle tissue. Such information is useful for understanding population variability and trophic dynamics. Another potential goal is to use δ15N and δ13C of fish scales preserved in sedimentary records to test for long-term relationships between nutrient input and trophic level on relative changes in the population sizes of sardines and anchovies, as inferred from fish scale deposition rates.
I am interested in starting research in Hawai’i in the areas of 1) history of Hawaiian fish ponds (by taking sediment cores in the ponds), 2) reconstructing past changes in ocean climate from isotopes and trace elements found in fossil coral skeletons, 3) examining changes in runoff and nutrients with trace elements that have been incorporated into living and fossil coral skeletons.
An interesting link: http://www.mbari.org/news/news_releases/2006/forams.html