Golden Alga in Texas

Archived News Release

Nov. 3, 2003

Experts Target Harmful Golden Algal Blooms

FORT WORTH, Texas — An international group of experts assembled by the Texas Parks and Wildlife Department here Oct. 24 and 25 outlined an ambitious plan for dealing with golden alga blooms that have killed more than 17 million fish in Texas in recent years.

Researchers from Norway, Sweden, Germany, Texas and other states shared knowledge about the golden alga Prymnesium parvum as the first step toward developing methods of preventing or controlling blooms. "We need better ways of detecting and managing or even preventing these outbreaks, especially in large bodies of water, where fish kills can be devastating to the local economy," said Larry McKinney, Ph.D. and director of TPWD's Resource Protection Division.

Golden alga is a one-celled organism that can undergo photosynthesis and can also produce several different chemicals capable of killing fish, clams, and the alga's predators. Unlike the red tide familiar to coastal residents, Prymnesium does not appear to be harmful to humans, wildlife or livestock.

Golden alga kills fish by releasing toxins into the water that cause fish gills to bleed internally and lose their ability to work properly. Since 2001, there have been fish killed by golden alga at 23 reservoirs in Texas. Just one such kill, which was at Possum Kingdom Reservoir in 2001, is estimated to have resulted in $16 to $18 million in economic losses to surrounding communities.

Streams and reservoirs west of Interstate Highway 35 have proven to be especially vulnerable to outbreaks of golden alga in Texas. Various factors appear to favor algal blooms, including high salinity, low stream flows, the presence of nitrogen and phosphorus in runoff into streams, and seasonal changes in water temperature.

While TPWD has developed ways of avoiding fish kills in its fish hatchery ponds, cost-effective methods are needed for preventing fish kills in large bodies of water.

The experts agreed that while much is known about the organism, much remains to be learned. The panel of experts recommended that TPWD monitor reservoirs during algal blooms, do basic research about how golden alga grows and becomes harmful, and test methods of control that have shown promise in other countries. One of the more major needs is a portable device that can be used to detect the alga, which is difficult to identify except with an electron microscope. Experts also agreed that the public needs to be kept fully informed about all these activities and that the full economic impacts of fish kills need to be determined.

The most important result of the golden alga meeting was the increased communication and commitment of scientists and managers to work together to manage harmful golden alga blooms and reduce their impacts.

For now, TPWD fishery and resource employees are conducting a historical analysis of past fish kills to use in predicting and controlling future blooms, are studying the genetics of the Texas golden alga to see if it is the same as other golden alga worldwide, are surveying the state's major rivers and reservoirs to determine the alga's distribution, and are creating a Web site about golden alga in Texas. This Web site will be launched in January and will provide suggested actions the public can take, answers to frequently asked questions, and the locations of golden alga fish kills. Additionally, TPWD will soon request coordinated proposals for research projects to address the most pressing needs and questions regarding golden alga in Texas.

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Take Action
  • Report Kills - If you see a fish kill or suspect golden alga, contact TPWD's 24-hour communications centers at 512-389-4848 (Austin).
  • Get the Facts - TPWD has collaborated with the Texas Commission on Environmental Quality and other entities to produce a golden alga information card. Download a PDF from the TCEQ website or request a free hard copy from TPWD at