Accession Number : ADA313762

Title :   Small-Scale Physical Processes Related to the Dynamic Photosynthetic Response of Phytoplankton Entrained in the Euphotic Zone of the Ocean.

Descriptive Note : Final technical rept.,

Corporate Author : NORTH CAROLINA STATE UNIV AT RALEIGH

Personal Author(s) : Kamykowski, Daniel

PDF Url : ADA313762

Report Date : 30 JUN 1995

Pagination or Media Count : 13

Abstract : Phytoplankton directly influence many optical and acoustic characteristics of the oceanic water column. Under nutrient sufficient conditions (Falkowski et al., 1992), phytoplankton activity is regulated both by the varying photosynthetically active photon fluence density (PPFD) exposure and by the photosynthetic potential of the individual cells throughout the water column (Marra, 1978a; 1978b). PPFD at the sea surface varies over a range of time scales due to clouds, and day/night and seasonal cycles (Kirk, 1983). Subsurface PPFD exhibits spectral changes with depth due to wavelength-dependent exponential attenuation (Kirk, 1983). Additional temporal variation in subsurface PPFD results from dissolved organic matter (DOM) and particulate organic matter (POM) patchiness (Parsons et al., 1984a). Near surface water motion, the net effect of turbulent mixing, surface and internal gravity waves, wind drift, Langmuir circulation and larger scale flow (Denman and Gargett, 1983), transports algal cells through the fluctuating PPFD field. Some cells act like neutral Lagrangian particles, but most possess an inherent motility due to buoyancy (S nayda, 1970; Walsby and Reynolds, 1980) or swimming (Roberts, 1981; Kamykowski et al. 1988). The physical and biological motion vectors combine to determine phytoplankton trajectories. Since the emphasis here is PPFD exposure of individual phytoplankton cells, vertical displacement is of primary concern (Kamykowski, 1990; Yamazaki and Kamykowski, 1990). One aspect of the work in his report dealt with the development of the Physical Motion instrument (PMI) to monitor water motion in over biologically significant time scales.

Descriptors :   *OZONE, *PHYTOPLANKTON, *PHOTOSYNTHESIS, *EUPHOTIC ZONES, CLOUDS, DENSITY, OPTICAL PROPERTIES, OCEAN SURFACE, NEUTRAL, PHYSICAL PROPERTIES, WATER, CELLS, DISPLACEMENT, MOTION, TURBULENT FLOW, NUTRIENTS, CYCLES, SPECTRA, DRIFT, PARTICLES, SEASONAL VARIATIONS, VERTICAL ORIENTATION, SCALE, ORGANIC MATERIALS, SURFACE WATERS, DAY, INSTRUMENTATION, PHOTONS, PARTICULATES, MIXING, NIGHT, FLOW, TRAJECTORIES, SEA WATER, DISSOLVING, INTERNAL WAVES, ACOUSTIC PROPERTIES, ALGAE, BUOYANCY, SWIMMING, LAGRANGIAN FUNCTIONS, GRAVITY WAVES.

Subject Categories : Biology
      Biological Oceanography

Distribution Statement : APPROVED FOR PUBLIC RELEASE