Update on Golden Algae
Galen Jons, Fisheries Biologist
The recent fish kills at lakes E.V. Spence and O.H. Ivie are testament to the fact that we have Golden Algae Prymnesium parvum in our area. It has also been found in lakes Moss Creek and Colorado City. Whether it is spreading or not remains unclear. Authorities suspect this algae has been present in many areas of Texas for a long time. Conditions brought on by the drought seem to have provided favorable conditions for this algae to bloom and cause problems for fish populations.
There is evidence that under normal conditions, the many types of green algae will out-compete the Golden Algae and prevent it from blooming. However, with lack of freshwater inflows, some area lakes have become somewhat salty. Golden Algae are considered an estuarine species, primarily inhabiting the brackish coastal waters. The current water conditions in West Texas are favorable to their development, and they are able to out-compete the green algae forms.
As Golden Algae blooms, it gives off a mixture of toxins known collectively as prymnesin, which inhibit ion and gas exchange in gill-breathing organisms. They basically cause fish to suffocate. These toxins seem to be particularly prevalent on cloudy days and in the more brackish (saltier) waters.
There is no real known cure for Golden Algae. It can be treated with ammonia, but this is only applicable in small, enclosed environments, such as aquaculture and hatchery ponds. Not only would it be cost-prohibitive to treat a large lake, but the ammonia could kill other beneficial organisms.
The only real hope seems to be a massive influx of freshwater, meaning an end to the current drought. There are other sources of salt in the watershed, such as uncapped abandoned water wells and other sources of pollution that can eventually be eliminated to help reduce the problem. The main emphasis is to try to keep the water fresh.
There is also evidence that fish will avoid a Golden Algae bloom, if possible. They will swim to unaffected waters. Bottom-dwelling fishes are also less likely to contact the toxins, as the algae occurs mostly in the upper water column where it can get sunlight.
While fish kills from Golden Algae have been significantly large in lakes Possum Kingdom and Granbury, they have, so far, been relatively minor in other lakes. However, the fact remains that it can be potentially devastating, and is probably the biggest single threat to our area fisheries (aside from lack of water).
It is important not to confuse Golden Algae with Largemouth Bass Virus
(LMBV). LMBV is an actual virus, and a totally different organism than
algae. LMBV affects primarily adult largemouth bass, and does not have
nearly the impact that Golden Algae can have on a fishery. Although LMBV
was 'discovered' by the media prior to Golden Algae a few years ago, it
appears that the algae has been in Texas a lot longer, possibly since
the 1960's or earlier.
For more information on Golden Algae, visit our webpage at
http://www.tpwd.state.tx.us and do a search for "golden algae".
Texas Parks and Wildlife Dept.
5325 N. 3rd
Abilene, TX 79603
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