General Information

Event name: US-05-024
Nature of the harmful event:
Water Discoloration , Seafood toxins , Mass mortalities
Event directly affected:
Natural Fish , Aquaculture Fish , Shellfish , Humans
Toxicity detected: Yes (Approximate range: Up to 77 mouse units)
Associated syndrome: NSP , Aerosolized toxins effects
Unexplained toxicity: No
Species implicated in toxin transmission (transvector): No reported cases of NSP
Report the outcome of a monitoring programme: No
Event occurred before in this location: Yes (Texas red tides occur every few years, increasing frequency.)
Individuals to contact: Byrd, Meridith

Location & Date

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Location: Latitude: , Longitude:
General location information: Texas coast and the Gulf of Mexico, Texas
HAB Area code(s): US-18
Additional location information: Approximately 80 miles of Texas Gulf coastline, Corpus Christi Bay (487 sq km), and the Lower Laguna Madre (300 sq mi). CC Bay and the LLM are semi-enclosed estuaries.
Bloom event dates (yyyy/mm/dd): Start: 2005-10-11, End: 2006-02-12
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information: Bloom began 12 Sept 2005 near South Padre Island, Texas. Bloom persisted at South Padre while moving up the Texas coast along the gulf side of Padre Island and was confirmed in Corpus Christi Bay on 12 October 2005. Bloom ended at South Padre Island around Nov. 1 and the Corpus Christi area bloom subsided mid-November. Waters remained closed to shellfish harvesting from November 1, 2005 to February 12, 2006.


Causative organism known: Yes
Causative Species/Genus: Karenia brevis (9,000,000 cells/L)
Near South Padre Island
Co-Ocurring Species/Genus:
Chlorophyll concentration, if known: µg/l
Additional bloom information: Trichodesmium and Karenia mikimotoi were also seen in conjunction with K. brevis.
Event-related bibliography:

Environmental Conditions

Weather: Turbidity (NTU): Wind direction:
Stratified water: Oxygen content (nL/L): Wind velocity:
Temperature (°C): Oxygen saturation %: Current Direction:
Sechhi disk (m): Salinity: Current Velocity: 0
Nutrient information:
Temperature Range During Event: Max: 32 °C, Min: 17 °C
Salinity Range During Event: Max: 38, Min: 22
Bloom location in the water column:
Growth Comments Bloom began in late summer. Temp. and salinity readings were taken very sporadically and may not be the true minimums and maximums. Also, only surface sampling was done so it is not known if a subsurface bloom occurred.
Additional Environmental information:

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Karenia brevis Brevetoxins 77 mouse units Bioassay-Mouse
Kit used: No Type of kit used:
Additional information: The Texas Department of State Health Services conducted mouse bioassays on oyster tissue and used these numbers to close some Texas bays to shellfish harvesting from Nov. 1, 2005 - Feb. 12, 2006
Economic losses: The South Padre Island Convention and Visitors Bureau compared hotel occupancy numbers from 2004 and 2005 and found that from 9/15/05 to 10/25/05 there were 32 days where occupancy was less than the previous year. Some days the numbers were substantial,
Management decision:
Additional harmful effect information:
Updated at 06:39 on 14 May 2018