1. Monitoring Levels of Brown Tides in the Waters of Laguna MadreBy
Craig Aumack

2. Overview Laguna Madre Brown Tides and their ecological impacts
Goals of project
Using ArcView for spatial/temporal analysis
Summery and further study

3. Laguna Madre

4. Brown Tides Aureoumbra lagunensis 5 to 6 x 109 cells Liter-1 NH4+
NO2- + NO3-
Aureoumbra lagunensis
5 to 6 x 109 cells Liter-1

5. Harmful Effects of Brown Tides
Over 120 km2 of Seagrass Beds Killed
Reduction in Larval Fish Recruitment
Change in Benthic and Pelagic Trophic Structures
Cost the South Texas Coast Several Million in the Tourism and Fishing Industries

6. Goals of Project
Determine the severity of phytoplankton abundance at given locations throughout Laguna Madre
Establish the extent to which the Brown Tides reach during their blooms
Judge the changes in bloom extent and abundance over time

7. ArcView Analysis HUC and reach files imported from NHD website
Files aligned and converted to shapefiles in ArcView 3.0

8. Data Analysis Added Database file from MS Excel Added Event theme
(LatDD + LongDD)
Interpolated Grid for chl A concentrations
4 mile radius

9. Spatial Results provide largest amounts of nutrient inflow 1994
= Areas that
provide
largest
amounts of
nutrient
inflow

10. Changes Over Time
1994
1996
1997

11. Summery
Large abundances of A. Langunensis, Brown Tides, have caused massive damage to Laguna Madre
The Brown Tides seem to be contained to and thrive within areas of high nutrient loading
The presence of phytoplankton has declined in the years of decreasing, nutrient rich, freshwater inflow

12. Problems concentrations in a year of little freshwater inflow Why?
1997
1999
= Increasing chl A
concentrations
in a year of little
freshwater inflow
Why?

13. Further Research
What other sources, besides freshwater, could be contributing to the nutrient loading of Laguna Madre?
What is maintaining the Brown Tides population in dormant years?
What freshwater balance is needed in order to prevent eutrophication, nutrient loading, and hypoxia.

14. Acknowledgements Data Collection PhD. Ken Dunton (UTMSI)
Lanny Miller (UTMSI)
Heather Alexander (UTMSI)
Curtis Suttle (EPA-Gulf of Mexico)
Data Organization
Addie Fretz (UTMSI)
Technical Assistance and Hypoxia Consult
Jeff Baguley (UTMSI)