Invasive Species in our local
Waterways
By John Reinke
By John Reinke
Several species of invasive amphibians, reptiles, mollusks and mammals have established themselves in King County's lakes, rivers and streams. his piece discusses the three species that I've observed in the Sammamish River. It is almost a certainty that they can also be found in Bear Creek, which flows into the Sammamish River.
The three species are: Asian clam (Corbicula fluminea), American bullfrog (Lithobates catesbeianus), and the red-eared slider turtle (Trachemys scripta elegans)
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credit: John Reinke |
The American bullfrog is native to the eastern United States, but has spread throughout the country. It is a voracious feeder, and will consume anything that can fit in its large mouth. Body length can be as long as six inches, with the legs adding as much as another ten inches. Very large bullfrogs can weigh almost two pounds. I have seen and photographed them in and near the Sammamish River.
It has proven easy to raise in ponds for commercial sale. Consequently, the species is now factory farmed in many parts of the world for food. According to the New York Times, more than two million bullfrogs are imported live into the San Francisco Bay Area every year. The problem is that they bring with them the deadly chytrid skin fungus, which has wiped out hundreds of frog species worldwide. (It is not harmful to humans.) A study of nearly 500 fresh-bought frogs from San Francisco, Los Angeles and New York found that 62 percent were infected with this fungus. A few manage to escape and thus help spread the fungus in the U.S.
Locally, these bullfrogs outcompete (and also eat) native species, which are in decline partly as a result. Bullfrogs also consume ducklings, garter snakes, and even the native western pond turtle. That's why the King County environment website says: "If you catch one, feel free to eat it!"
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Credit: John Reinke |
Like the American bullfrog, the red-eared slider is native to the eastern U.S. It is the most commonly sold pet turtle across the country. This has greatly contributed to its spread, as some escape into the wild and others are let go by owners who no longer want them.
Their name comes from the distinctive red patch of skin around their ears. The "slider" part comes about from their ability to quickly slide into the water from rocks and logs. Red-eared sliders eat a variety of animal and plant materials including fish, crayfish, tadpoles, snails, crickets, aquatic insects and numerous aquatic plants.
Red-eared sliders have overwhelmed native western pond turtles to the extent that according to Wikipedia, the latter have not been found in the Puget Sound area since 2007.