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Invasive Species

Feral hogs trapped at St Marks NWR, FL. Photo by: W. Barichovich.

ARMI conducts research on the ecology of invasives, their impacts on native species, and how invasive species can be reduced or eradicated. Habitat used by amphibians has been exposed to many types of invasives through deliberate or accidental introductions. For example, sport fish deliberately introduced to ponds and streams in the western US that were formerly fishless, have been associated with the loss of amphibians in those water bodies. In another example, the American bullfrog of the Eastern US was introduced into the Western US through a combination of introductions into ponds for bait, and escapes from frog farms. The American bullfrog has been a relentless predator of several species already in conservation trouble in the Western US.

What types of problems do invasive species cause?
Some species harm native species directly by preying on them or competing with them for resources, and some modify or destroy the habitat used by native species.

Where do invasive species come from?
Some come from deliberate introductions such as biological control, stocking for hunting, fishing, or spreading bait species. Some are accidental escapes from pet stores, farming/aquaculture facilities, and ornamental gardens. Some animals are released by pet owners or teaching labs. Some species hitchhike with materials otherwise deliberately moved such as garden plants, ballast water, boats and nets.

Terms Related to Invasive Species

Invasive species: Plant, animal or pathogen that is not native to an area, and "whose introduction does or is likely to cause economic or environmental harm or harm to human health." [US Executive Order 13112. 1999]

Injurious Wildlife (defined by Lacey Act) - Mammals, birds, amphibians, reptiles, fish, crustaceans, mollusks and their offspring or gametes that are injurious to the interests of human beings, agriculture, horticulture, forestry, wildlife or wildlife resources of the United States. Plants and organisms other than those listed above cannot be listed as injurious wildlife. http://www.fws.gov/fisheries/ans/pdf_files/InjuriousWildlifeFactSheet2007.pdf

Nonindigenous species: Any species or other viable biological material that enters an ecosystem beyond its historic range, including any such organism transferred from one country into another. (Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990) http://anstaskforce.gov/Documents/nanpca90.pdf

Aquatic nuisance species: A nonindigenous species that threatens the diversity or abundance of native species or the ecological stability of infested waters, or commercial, agricultural, aquacultural or recreational activities dependent on such waters. (Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990) http://anstaskforce.gov/Documents/nanpca90.pdf

Resources

http://www.fws.gov/invasives/laws.html
http://www.invasivespeciesinfo.gov/laws/main.shtml

ARMI Products on Invasive Species

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Endangered fish in endangered frog habitat with several parasites from the pet trade.

USGS

Introduced parasites of freshwater fish in southern California, U.S.A.

Authors: Kuperman BI, Matey VE, Warburton ML, Fisher RN | Date: 2002 | Outlet: pp. 407-411 in: Proceedings of the 10th International Congress of Parasitology - ICOPA X. Monduzzi Editore S.p.A. - MEDIMOND Inc., Bologna, Italy. 660 pp. | Format: .PDF

Sampling for amphibians in northern Baja California.

Robert Fisher

Occurrence of Batrachochytrium dendrobatidis in anurans of the Mediterranean region of Baja California, Mexico

Authors: Peralta-Garcia A, Adams AJ, Galina-Tessaro P, Briggs CJ, Valdez-Villavicencio JH, Hollingsworth BD, Shaffer HB, Fisher RN | Outlet: Diseases of Aquatic Organisms | Format: URL

Chytridiomycosis is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) and is regarded as one of the most significant threats to global amphibian populations. In M?xico, Bd was first reported in 2003 and has now been documented in 13 states. We visited 33 localities and swabbed 199 wild-caught anurans from seven species (five native, two exotic) across the Mediterranean region of the state of Baja California. Using quantitative PCR, Bd was detected in 94 individuals (47.2% of samples) at 25 of the 33 survey localities for five native and one exotic frog species. Only the non-native Xenopus laevis tested negative for Bd. We found significant differences between mean Bd loads of different species, and that remoteness and distance to agricultural land were the best positive predictors of Bd prevalence. These are the first Bd-positive results for the state of Baja California and its presence should be regarded as an additional conservation threat to the region?s native frog species.

California Red-legged Frog, [I]Rana draytonii[/I], with radio transmitter belt.

USGS Point Reyes

Frogs on the Beach: Ecology of California Red-Legged Frogs (Rana draytonii) in Coastal Dune Drainages

Authors: Halstead BJ, Kleeman PM | Date: 2017-04-30 | Outlet: Herpetological Conservation and Biology 12:127–140 | Format: .PDF

California Red-legged Frogs (Rana draytonii) are typically regarded as inhabitants of permanent ponds, marshes, and slow-moving streams, but their ecology in other habitats, such as drainages among coastal dunes, remains obscure. Because coastal dune ecosystems have been degraded by development, off-highway vehicle use, stabilization, and invasive species, these unique ecosystems are the focus of restoration efforts. To better understand the ecology of California Red-legged Frogs in coastal dune ecosystems and to avoid and minimize potential negative effects of dune restoration activities on these rare frogs, we studied their spatial ecology, habitat selection, and survival in coastal dune drainages at Point Reyes National Seashore, California, USA. All 22 radio-marked frogs remained in their home drainages throughout the spring and summer of 2015 and, with some notable exceptions, most remained close to water. Local convex hull home ranges of four out of five California Red-legged Frogs with > 20 observations in dunes were < 1,600 m2. At the population level, frogs were 1.7 (1.2-4.4) times more likely to select sites 1 m closer to water, and were 83 (2.0-17,000) times more likely to select sites with 10% greater percent cover of logs that served as refuges from environmental extremes and predators. On average, California Red-legged Frogs avoided the invasive plants Iceplant (Carpobrotus edulis) and European Beachgrass (Ammophila arenaria). Frogs were 0.68 (0.32-0.89) and 0.55 (0.24-0.75) times as likely to select areas that had 10% greater cover of these plants, respectively. Assuming constant risk of mortality, California Red-legged Frogs had an annual survival rate of 0.70 (range, 0.27-0.96) in coastal dune drainages. This relatively high survival rate suggests that coastal dune drainages provide a locally important habitat for California Red-legged Frogs. Restoration practices that maintain wetted drainages with logjams are likely to benefit California Red-legged Frogs.