Results
We observed several types of small-scale structure in bio-optical properties during our 1998 experiment in East Sound. We saw thin layers of phytoplankon that persisted for several hours. We also observed many instances of several-fold changes in properties over vertical scales of 20-40 cm. We are in the midst of data processing and analysis of our extensive data set. Some of our findings are shown in the 'time-series of high-resolution profiles' section below.
Our results suggest that additional direct assessment of the trophic implications of persistent thin layers is needed, with particular emphasis on the potential for enhanced grazing, steeper local gradients in nutrient flux and regeneration, and variations in particle flux from the euphotic zone. Our work with biological microstructure suggests that previous observations of small-scale biological patchiness may not have been observations of stochastic fluctuations in biological structure (i.e., patchiness), but under-sampled observations of persistent, small-scale structure. Centimeter-scale organization of planktonic biomass forces a re-evaluation of water column rate processes, and challenges our existing paradigms for sampling and experimentation over scales of meters and 10's of meters.
The following links are plot galleries and data summaries for instruments deployed by the Plankton/Bio-Optics group and other investigators during the Thin Layers 1998 field study. All of the plots in the galleries below cover the same six hour periods beginning with 10-June-1998, 14:00 PDT and ending with 24-June-1998, 20:00 PDT. Selection of the data shown below is intended to illustrate the inter-relationship between small-to-large scale physical and biological properties.
** Note: Unless otherwise indicated, the data shown below is copyrighted © 1999 by Oregon State University, College of Oceanic and Atmospheric Sciences. Use of the data shown requires the explicit consent of Dr. Timothy J. Cowles or the investigator indicated.
- Selected maps of East Sound, Orcas Island, Washington showing the location of Orcas Island with respect to other Islands in the San Juan's Islands group. Also available is a bathymetry plot of East Sound indicating the position of the R/V Henderson and thermistor chain deployment sites.
- ADCP mooring "A" (placed close to the R/V Henderson) surface-referenced scattering intensity and north/south and east/west horizontal velocity plots. Data courtesy of Dr. A. Wiedemann.
- Time-series of high-resolution SlowDROP profiles from the R/V Henderson.
- Six hour, color-filled contour plots of the data from thermistor chain deployments in East Sound, in addition to notes on each deployment site.
- Weather conditions during SlowDROP deploymentsWind Speed and Direction, Air Temperature and Barometric Pressure Plots During SlowDROP Deployments. Data courtesy of Dr. P. Donaghay.
- Tethered Spectral Radiometer Buoy (TSRB) data presented on the Remote Sensing Ocean Optics web site. This site contains information on the format of the data as well as notes on conditions during the instrument's deployments.
Reports, Presentations and Publications
- A Preliminary Investigation of Phytoplankton Pigment Composition and In-Situ Spectral Absorption Measurements in East Sound, Orcas Island, Washington. Lisa B. Eisner, Michael S. Twardowski and Timothy J. Cowles. Presented as a poster at the American Society of Limnology and Oceanography (ASLO) annual conference, Santa Fe, NM 1999.
