Buskey, E. J.. University of Texas Marine Science Institute, buskey@utmsi.utexas.edu
Liu, H. J.. University of Texas Marine Science Institute, hongbin@utmsi.utexas.edu
Villareal, T. A.. University of Texas Marine Science Institute, tracy@utmsi.utexas.edu
Wysor, B. University of Southern Louisiana, wysor@usl.edu
Collumb, C. University of Texas Marine Science Institute, collumb@utmsi.utexas.edu

 
EL NINO AND THE LAGUNA MADRE: DON'T YOU MAKE MY BROWN TIDES BLUE?
 
The Laguna Madre has experienced a persistent bloom of Aureoumbra lagunensis for over eight years. The persistence of this bloom relates to the normally hypersaline conditions in Laguna Madre (40 - 60 PSU), that favors the growth of A. lagunensis. Above normal rainfall in 1997 associated with El Nino reduced the salinities in Baffin Bay from >40 PSU to <20 PSU. A. lagunensis cell densities dropped from > one million cells per ml in July 1997 to ca. 200 cells per ml in January 1998. During this time of low brown tide density, the Laguna Madre experienced successive blooms of diatoms (Rhizosolenia spp) and cyanobacteria. Nutrient concentrations remained low throughout this succession of blooms (N < 2 uM, P <0.1 uM), revealing no clear nutrient source to fuel them. Hypersaline conditions returned in 1998 and brown tide densities increased to >500,000 cells per ml by summer. The extraordinary persistance of the brown tide and the unusual sequence of intense blooms may be related in part to disruption in zooplankton grazing. Baffin Bay had low rates of microzooplankton grazing during both hypersaline and hyposaline conditions compared to nearby Corpus Christi Bay.
 
Day: Friday, Feb. 5
Time: 09:45 - 10:00am
Location: Eldorado Hotel
 
Code: SS42FR0945E