Lavallee, D. C. University of California, Santa Barbara, daniel@crustal.ucsb.edu

FRACTAL AND NONFRACTAL PATTERNS RELATED TO PLANKTON DYNAMICS

Our understanding of plankton dynamics is evolving rapidly, so that our sampling methods and the associated statistics need re-evaluation. Two examples are given. 1) Fractal ocean turbulence drives plankton distribution and behavior, producing inter alia a fractal patchiness, and requires appropriate statistics based on randomness in a fractal domain. In an analysis of physical and chemical data from an oceanographic buoy near Bermuda, the power spectra show scale invariance suggesting that the concerned processes have fractal patterns over long periods. Note that the chlorophyll fluorescence data shows a similar behavior. However, for a few samples of the adsorption of light-beam transmission, a measure of phytoplankton cell abundance, the power spectra have an exponential decay. The same functional behavior characterizes the numerical solutions of the Lorenz equation in the chaotic regime. The pattern is inferred to be produced by biological changes, such as daily cell division, blooms and grazing, superimposed on the nonlinear fluctuations. 2) An analysis of published zooplankton species distribution at an equatorial Pacific Ocean station ranks the species by the number of individuals in a species. All ranked groupings have the character of a geometric series. This requires a new oceanic application of the appropriate diversity index.

Day: Tuesday, Feb. 2

Time: 08:45 - 09:00am

Location: Hilton of Santa Fe

Code: SS02TU0845H