TPWD News Release — Feb. 17, 2012
This type of alga, which does not cause harm to humans or other mammals, has been the cause of substantial fish kills in over a dozen lakes in West and North Central Texas since 2001, including E. V. Spence and Possum Kingdom.
On Feb. 13, Texas Parks and Wildlife Department (TPWD) officials received complaints of dead fish floating on Brady Lake. Fisheries biologists conducted a fish kill count and collected water samples the following morning. Signs of an active golden alga bloom were present, according to biologists, including yellowish-colored water, foaming at the shore, and fish with hemorrhaging gills. An algal cell count and toxicity test confirmed a golden algal bloom.
“Some lakes that are hit with golden alga tend to be affected year after year, and the fisheries are severely impacted,” said Mandy Scott, Assistant Fisheries Biologist in TPWD’s San Angelo Inland Fisheries Management office. “But, other lakes, like Sweetwater or Whitney, experience blooms once or every few years, and the fisheries are able to rebound. We’ll have to wait and see how Brady Lake responds to this.”
TPWD is closely monitoring the bloom and its impacts, and will evaluate the need for restocking with fish after the bloom subsides.
Since the initial widespread blooms in 2001 that killed thousands of fish in multiple Texas lakes, TPWD and research partners have been investigating possible causes, impacts, and treatments of golden alga. So far, scientists have determined that the alga seems to be already present in many Texas water bodies, but water conditions must reach certain levels before the alga blooms and turns toxic. Salinity and hardness, temperature, and nutrient availability are all important factors. During droughts such as the one experienced in 2011, high evaporation rates and reduced freshwater inflows can cause increased salinity and hardness in reservoirs. So far, scientists have been able to control golden alga in small ponds with algaecide, but nothing practical has been found for effectively treating large reservoirs.
More information on golden alga and its impacts on Texas water bodies can be found at http://tpwd.texas.gov/landwater/water/environconcerns/hab/ga/.