- Author: Leigh Taylor Johnson
Did you have a pet Red-Eared Slider Turtle (Trachemys scripta elegans) when you were growing up? The distinctive red stripe on the side of the head is attractive and makes it easy to identify them.
The red-eared slider turtle is native in much of the mid- to south-central United States. However, it is an invasive species in California, Oregon, Washington and many other states. The US Geological Survey has mapped areas where it is native and not. Click this link and then scroll down to see the map.
California Department of Fish and Wildlife’s (CDFW’s) Outdoor California magazine reports that non-native pet turtles, like the red-eared slider, are a threat to California’s only native freshwater turtle, the Western Pond Turtle (Emys marmorata). Sliders became a problem because so many owners set them free in a local pond or lake. CDFW recommends removing red-eared slider turtles and other non-native species, like bullfrogs, that eat or compete with native species. They also recommend leaving native western pond turtles in peace. (Be patient if you click on the Outdoor California link; the file downloads slowly because it has lots of information and great photos.)
Why are red-eared sliders such a threat? Oregon Department of Fish and Wildlife reports that they compete with native turtles for food, nesting and basking space, and hiding places. Native turtles have no immunity to parasites and diseases carried by red-eared sliders. Turtles can live more than 20 years, so if you set them free, they will pose a threat for a long time! Dhi (see photo below) has been a pet for 18 years. Her human family decided to keep her, instead of releasing her to a local pond.
Columbia University explains that the red-eared slider plays important roles as both predator and prey in its native range. Because they are aggressive and bold, they compete for both food and space with native turtles, where they are introduced.
Buyer Beware! Small turtles sold as pets also cause Salmonella infections in humans. In May 2013 the federal Centers for Disease Control and Prevention reported a salmonella outbreak that affected 391 people in 40 states and the District of Columbia. 70% of the sick people had been exposed to turtles, and 89% of these people had been exposed to small turtles (shell less than 4 inches long). 30% of sick people with small turtles had bought them from a street vendor and 13% had bought them from a pet store. The CDC notes that in 1975 the US Food and Drug Administration banned sales and distribution of turtles less than 4 inches long, so it’s surprising that they are still being sold.
To download a red-eared slider coloring sheet you can print for kids, click on the link at the bottom of this post.
UC Cooperative Extension Advisors Leigh Johnson, Sabrina Drill and Darren Haver trained 181 employees of public works, parks and a UC Research and Extension Center in Spring 2013 to recognize, report and decontaminate their field gear to avoid spreading aquatic invasive species.
Click for Red-eared Slider Coloring Sheet from USGS
- Author: Leigh Taylor Johnson
This icky sounding aquatic invader threatens tourism, fisheries and even hydropower facilities that depend on our streams and rivers. Why?
Rock snot, aka didymo (Didymosphaenia geminata), is a one-celled alga or diatom. Each tiny didymo grows a gelatin-like stalk it uses to attach itself to rocks, plants and just about any available surface under the water. Didymos reproduce by dividing and so do their stalks, eventually creating a branching network that feels like wet cotton or wool. Thus, the problem...
Didymo can “bloom” (grow to very large numbers) and accumulate in large globs that look slimy, hence the name “rock snot.” Check out the USDA National Invasive Species Information Center for a video of a New Zealand stream with masses of blooming didymo.
Blankets of didymo can reach 8 inches thick, smothering mayflies, stoneflies, caddisflies and other native, bottom-dwelling aquatic life that are food for fish and birds. Didymo mats also foul spawning grounds for salmon and trout and interfere with water flow. Pennsylvania’s “Aquatic Invasive Species (AIS) Action Plan: Didymo” has a nice summary of didymo’s natural history and the harm it causes.
In California, didymo is found in the Sierra Nevada mountains, the north-central part of the state, and the south fork of the American River. Scientists thought for many years that didymo lived only in clean, cold-water streams and rivers. New research has found that it can tolerate water as warm as 80∘ F and it grows faster when nitrogen and/or phosphorus levels rise. This means that didymo is also a threat to streams and rivers at lower elevations and in warmer climates.
How does didymo spread to new streams and rivers? Like many aquatic invaders, didymo hitches a ride with people. It can survive at least 40 days in cool, damp and dark conditions. So, didymo spreads easily on fishing tackle, neoprene waders and wetsuits, compartments on boats and other gear, felt soles of wading boots, clothing and even the family dog.
What can you do to avoid spreading didymo to new streams and rivers? Start with the slogan, Check, Clean, Dry! In other words, before you leave a site, CHECK your gear, clothing, the dog’s feet, truck tires if you forded the stream, etc. for obvious (and hidden) clumps of algae and leave them there. If you find any algae globs later, dry them and soak them in bleach for at least 4 hours. CLEAN your gear, waders, etc. by soaking and scrubbing for at least 1 minute in hot water, 2% bleach solution, antiseptic hand cleaner or dish detergent. Such cleaning is not practical for livestock and pets. So, let them (and your scrubbed gear) DRY completely and then wait another 48 hours before allowing them to contact or enter any other waterway.
For detailed decontamination protocols, visit Biosecurity New Zealand’s didymo pages.
Anglers, boaters and people who work in and around rivers and streams can be an early warning system for didymo both in cold-water streams and rivers, as well as in warmer and more polluted waterways. If you think you have seen didymo or “rock snot” report it to CA Department of Fish and Wildlife. See our “Rat on Aquatic Invaders” blog for instructions on how to report sightings of aquatic invasive species.
Scientists, fly-fishers, tribal agencies, conservation groups and others met in 2006 to document the problems didymo was causing and recommend action. The excellent White Paper they published in January 2007, a map of didymo locations, and a rough guide for field identification are available from US EPA Region 8.
UC Cooperative Extension Advisors Leigh Johnson, Sabrina Drill and Darren Haver trained 181 southern California public works, parks and UC research staff in Spring 2013 to recognize, report and decontaminate aquatic invasive species, including didymo or “rock snot.”
- Author: Leigh Taylor Johnson
Who ya gonna call? If you spot a suspected aquatic invader, where you report it depends on the critter or weed.
Remember to take photos with a camera or, even better, geo-tag them with a smartphone. Take a snapshot that shows just where you saw the invasive species, such as a streambed, lake or pond. Next, photograph the whole animal or plant and then add close-ups of distinctive features. For example, check mussels for “byssal” threads that attach them to surfaces and photograph them. If it’s a waterweed, add close-ups of leaves, flowers, roots, etc. Handle shellfish and plants carefully. AVOID picking up or getting close to crayfish, snapping turtles, clawed frogs, snakes or others that may be able to bite or scratch you!
If it’s an animal (mussel, clam, snail, crayfish, crab, fish, frog, snake, turtle, etc.) or a marine plant (such as the brownish Asian kelp that's also called wakame, or the little bright-green feathers called Caulerpa taxifolia), contact California Department of Fish and Wildlife’s (CDFW’s) invasive species hotline. You can reach them at (866) 440-9530. The message says it is the quagga and zebra mussel hotline, but they also handle other invasive animals and marine plants. Or, you can email them at invasives@dfg.ca.gov
Visit the CDFW online for their Invasive Species Report Form that you can fill out on your computer. Either print the form and send it with pictures or samples to the address on the form. Or, “print” the completed form as a .pdf file and email it to the above address along with e-photos. And, because dead creatures and seaweeds rot quickly, pictures may be the better way to go!
You will need to tell CDFW the name (if you know it) of the suspected invader and whether it is a plant, shellfish, snake, fish, frog, etc. Next, describe its size, color, shape and other distinctive features. Give the date and the California county where it was sighted, plus directions to the location where you saw it. (If you have geo-coordinates, give them, too.) Give the name of the land owner or manager, for example “John Doe” or CA Department of Parks and Recreation.
CDFW may need to contact you for more information, so they also ask for the first and last names and contact information of the person who sighted the suspected invasive species.
If the suspected invader is a waterweed, report sightings to the Agricultural Commissioner’s Department in your local county government. A list of county Ag Departments is available from California Department of Food and Agriculture First, click your county on the map. Look for your local Ag Department’s address and a phone number to call for instructions on how to submit a report and a sample. If you can get there quickly, you may be able to bag, tag, chill and deliver a waterweed specimen before it rots. Otherwise, spread out the waterweed, place it between sheets of absorbent paper and add a weight, so it will dry flat. Change the paper often, until the sample is completely dry.
Cooperative Extension Advisors Leigh Johnson, Sabrina Drill and Darren Haver trained 181 staff of public agencies and a UC research center in a Spring 2013 workshop series on how to recognize, report and decontaminate their gear to avoid spreading suspected aquatic invasive species.
- Author: Leigh Taylor Johnson
Look out, Kermit! There’s a plague of invasive frogs and they’ve got big appetites.
American Bullfrogs (Lithobates catesbeiana) arrived in California at least 100 years ago and are now widespread. Bullfrogs eat just about anything, such as other frogs and bullfrogs, toads, snakes, turtles, birds and mice. In fact, California Department of Fish and Wildlife found a young coho salmon inside a bullfrog! And they’re blamed for causing the decline of native western red-legged and yellow-legged frogs by eating and outcompeting them.
In contrast, the bullfrog’s (really big!) tadpoles mostly eat algae and aquatic plants. Some fish, aquatic insects, garter snakes and wading birds eat the tadpoles. For more information on American Bullfrogs, visit University of Michigan Museum of Zoology’s Animal Diversity Website.
African Clawed Frogs (Xenopus laevis) were used worldwide for human pregnancy tests in laboratories during the 1940’s and 1950’s. When newer technology arrived, the frogs were released. Some that were kept as pets were released when owners no longer wanted them or they simply escaped from home aquaria. African clawed frogs can tolerate salinity, low oxygen, silt, pollution and both acidic and alkaline waters (pH 5-9). When ponds dry up in the summer, they can estivate in the mud for up to 8 months and can go without food for up to a year.
African clawed frogs can reach 5 inches long and they have claws on the three outer toes of their front legs. They are voracious and prefer aquatic insects, but they will eat fish, other amphibians (including their own kind), birds and even decaying debris. The African clawed frog can reproduce by the age of 6-10 months and a female can produce 27,000 eggs each season. Their ability to escape predators, secrete toxins and resist infections enables them to live up to 10-15 years in the wild.
Visit Columbia University's Website to learn more about African Clawed Frogs.
So, if these “ribbiting” invaders are already widespread, why are we writing about them? Their stories show how important it is to avoid releasing aquarium pets or schoolroom animals into the wild, where they can spread and harm native species.
Information on invasive frogs was included at a Spring 2013 workshop series for southern California public agency employees who work in aquatic habitats. The workshop was conducted by UC Cooperative Extension Advisors Leigh Johnson, Sabrina Drill and Darren Haver.
- Author: Leigh Taylor Johnson
Getting the word out about especies invasoras acuáticas (aquatic invasive species) en Español is not just about translating English flyers and posters. For example the slogan, “Don’t Move a Mussel,” is catchy in English because it’s a play on words. The pun doesn’t work in Spanish. Myriam Grajales-Hall, News & Outreach in Spanish Program Manager for UC Division of Agriculture and Natural Resources, explains that English needs to be adapted, instead of translated, to Spanish. Adapting takes into account cultural differences and how each language is put together.
To address this challenge, UC Cooperative Extension Specialist Ted Grosholz and Advisors Jodi Cassell, Sabrina Drill, Leigh Johnson and Greg Giusti and California Sea Grant Extension Aquatic Resources Specialist Carolynn Culver teamed up with Grajales-Hall.
They held focus groups in northern and southern California during May and June 2013 to ask for advice from English- and Spanish-speaking boaters, anglers, kayakers, and staff of community organizations and the California Departments of Parks, Boating and Waterways, and Fish and Wildlife. The groups took a look at existing print materials and PSAs, gave their opinions on what else is needed, and suggested good ways to reach Spanish speakers who enjoy aquatic recreation.
The results are still being analyzed, but Grajales-Hall and her staff are already reaching out en Español. Click on these links to see their website article and YouTube video on especies invasoras acuáticas and their Facebook and Twitter pages en Español.
Renewable Resources Extension Act funding from US Department of Agriculture supported the focus group project.
