Accession Number : ADA518383


Title :   Physical and Biological Processes Underlying the Sudden Appearance of a Red-Tide Surface Patch in the Nearshore


Descriptive Note : Journal article


Corporate Author : SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA


Personal Author(s) : Omand, Melissa M ; Leichter, James J ; Franks, Peter J ; Guza, R T ; Lucas, Andrew J ; Feddersen, Falk


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a518383.pdf


Report Date : Jan 2010


Pagination or Media Count : 47


Abstract : The factors contributing to the timing and intensity of phytoplankton blooms (red tides) in very shallow water are poorly understood. Here, the sudden and brief (3h) appearance at the surface of an alongshore-parallel band of red tide is described. The bloom, near Huntington Beach CA, was dominated by the locally common red-tide forming dinoflagellate Lingulodinium polyedrum (F. Stein). Surface chlorophyll-a (Chl a) and temperature (T) were mapped with a novel GPS-tracked jetski. The surface red-tide band, with maximum Chl a7 microgram L-1, was visible for more than 3h, was located 500 m from shore (8m water depth), was 200m wide and extended 1km alongshore. The subsurface bloom, with maximum Chl a 30 microgram L-1, developed farther offshore, near the 17-deg C isotherm over 4-7 days prior to the surface appearance. A few hours before the surface band appeared, an intense Chl a patch was observed in 13m total depth in the mid-water column trough of a shoreward-propagating supertidal internal wave. The Chl a patch intensification was consistent with dinoflagellate vertical swimming interacting with the wave-driven circulation. In shallow water (12 m depth), vertical mixing, attributed to internal wave breaking, brought the Chl a patch to the surface. Warm water in very shallow water (depth 5 m) apparently blocked the Chl a patch from entering the surfzone. These observations highlight the role of small-scale physical and biological processes in determining the spatial and temporal characteristics of nearshore red tide blooms.


Descriptors :   *BIOLOGY , *SHORES , *INSHORE AREAS , *PHYSICAL PROPERTIES , PHYTOPLANKTON , SWIMMING , TIDES , CHLOROPHYLLS , PLANKTON BLOOMS , DINOFLAGELLATA , SURFACE PROPERTIES , SHALLOW WATER , REPRINTS , INTERNAL WAVES


Subject Categories : Biology
      Hydrology, Limnology and Potamology


Distribution Statement : APPROVED FOR PUBLIC RELEASE