WERC Highlights -- May 2007

California Sea Otters Spring Survey Numbers Up: Observers, led by scientists at the U.S. Geological Survey (USGS), counted a total of 3,026 California sea otters for the 2007 spring survey. This count marks a record high and a 12.4 percent increase over the 2006 count of 2,692. The latest 3-year running average is up 2.4 percent over the previous average, to 2,818 sea otters. To assess overall population trends, three-year running averages of spring counts are used to reduce the influence of vagaries in any given year’s count. The spring survey was conducted May 2-17, covering about 375 miles of California coast, from Point San Pedro in the north to Rincon Point in the south. Overall viewing conditions were more favorable than those during the spring 2006 survey, which could have positively influenced the survey counts this year. The information gathered from spring surveys is used by federal and state wildlife agencies in making decisions about the management of this small sea mammal. (Brian Hatfield, San Simeon, CA, 805-927-3893, brian_hatfield@usgs.gov)

Breakdown Products of Widely Used Pesticides Acutely Lethal to Amphibians: According to a newly published study co-authored by USGS and Southern Illinois University scientists, the breakdown products (oxons) of the three most commonly used organophosphorus pesticides in California’s agricultural Central Valley, chlorpyrifos, malathion and diazinon, are 10 - 100 times more toxic to amphibians than their parent compounds, which are already highly toxic to amphibians. The scientists conducted laboratory experiments to determine the acute toxicity of these pesticides and their oxons and have published the results in Environmental Pollution. Organophosphorus pesticides have been implicated in the declines of several amphibian species in the California Central Valley, and published information together with new unpublished data are revealing that these pesticides are posing serious hazards to the welfare and survival of native amphibians in California. Organophosphorus pesticides form the largest group of chemicals used in the control of pests, including invertebrates, vertebrates and, to a lesser extent, plants. See: http://www.werc.usgs.gov/pubbriefs/fellerspbmay2007.html. (Gary Fellers, Point Reyes, CA, 415-464-5185, gary_fellers@usgs.gov) Citation: Sparling, D.W., and G. Fellers. 2007. Comparative toxicity of chlorpyrifos, diazinon, malathion and their oxon derivatives to larval Rana boylii. Environmental Pollution 147:535–539.

Sea Otters: USGS scientist Brian Hatfield was contacted by the San Luis Obispo Tribune, Santa Cruz Sentinel, and KSBW-TV (NBC affiliate, Salinas, CA) about the 2007 spring survey of California sea otters. Stories also appeared in the San Francisco Chronicle, Monterey County Herald, San Jose Mercury News, and on WebWire.com. (Brian Hatfield, San Simeon, CA, 805-927-3893, brian_hatfield@usgs.gov)

Oxon Toxicity: Stories on the recent study by USGS and Southern Illinois University on the toxicity of three common agricultural pesticides and their breakdown products for amphibians ran at Central Valley Business Times.com and Yubanet.com. (Gloria Maender, Tucson, AZ, 520-670-5596, gloria_maender@usgs.gov)

Competitive Interactions Between a Non-native Annual Grass and Mojave Desert Perennials: Competition between native and non-native species can change the composition and structure of plant communities, but in deserts, the highly variable timing of winter and spring rainfall also influences non-native plant establishment, thus modulating their effects on native species. Much research has focused on the dramatic impact that the non-native annual grass red brome (Bromus madritensis spp. rubens) has on desert plant communities by fueling wildfires that injure and kill native plants. A study by scientists of the USGS, Nevada Agricultural Experiment Station, and University of Nevada, Reno, recently published in Biological Invasions, highlights red brome’s impact on perennial species in undisturbed habitat even before wildfire becomes a problem. Among findings from the field experiment, the growth of perennials declined when red brome established early in winter because the non-native grass had 2-3 months of growth and extracted soil moisture before perennials became active. See: http://www.werc.usgs.gov/pubbriefs/defalcopbmay2007.html (Lesley DeFalco, Henderson, NV, 702-564-4507, lesley_defalco@usgs.gov)

Mountain Yellow-legged Frogs: USGS scientist Robert Fisher was interviewed this week by KPCC, southern California public radio, about endangered mountain yellow-legged frogs and how trout stocking can affect ecosystems by introducing predators. Fisher was also interviewed by Zoonooz, the San Diego Zoo magazine, for an upcoming story about the captive breeding program under way for mountain yellow-legged frogs (the frogs are located at the zoo’s Conservation and Research for Endangered Species center); photos of the frogs and natural habitat were also provided. The May issue of Zoonooz magazine mentions the mountain yellow-legged frog breeding program in the President’s column, as a preview of the full article to come. (Robert Fisher, San Diego, CA, 619-225-6422, rfisher@usgs.gov)

Chaparral Researcher: The May 22, 2007 issue (#22) of the “Chaparralian,” the newsletter of the California Chaparral Institute (www.californiachaparral.org) describes the career and diverse research interests of USGS scientist Jon Keeley in its article “Jon E. Keeley: A True Chaparralian.” (Jon Keeley, Three Rivers, CA, 559-565-3170, jon_keeley@usgs.gov)

Bobcat Movement Study: USGS scientist Erin Boydston was interviewed by the Orange County Register for an environmental blog posted May 16, 2007, which is a follow-up story about “Oscar,” a bobcat the newspaper first reported about on April 1, one of several bobcats in a tracking study. Local residents who read the initial story have responded with sightings of kittens with two female bobcats that are part of the study, thus providing useful information to the researchers. USGS was also mentioned in a May 14 story in the Orange County Register in which volunteer Dick Newell was interviewed about an upcoming public field trip he’ll lead this weekend for a new educational program launched by the Irvine Ranch Land Reserve Trust called the Animal Behavior and Tracking Hike. See http://blogs.ocregister.com/environment/archives/2007/05/earth_update_on_oscar.html and http://www.ocregister.com/ocregister/sports/ocoutdoors/abox/article_1693886.php. (Erin Boydston, Irvine, CA, 714-508-4704, eboydston@usgs.gov)

California Clapper Rail: USGS scientists Mike Casazza and Cory Overton were interviewed for an article about USGS research on the endangered California clapper rail, a species of the intertidal margins of San Francisco Bay, for publication in the Invasive Spartina Project's first quarterly newsletter. The Invasive Spartina Project (ISP) is a regionally coordinated effort to address the rapid spread of four introduced and highly invasive Spartina (cordgrass) species in the San Francisco estuary. The newsletter will be geared towards interested parties working on ecology and wetland restoration in San Francisco Bay. See: http://www.spartina.org/. (Mike Casazza, Dixon, CA, 707-678-0682 ext. 629, mike_casazza@usgs.gov)

Postfire Reseeding: On May 18, 2007, USGS scientist Jon Keeley will be interviewed on NPR’s Science Friday program about postfire restoration options and treatments against erosion from the recent 820-acre brush fire in Los Angeles’ Griffith Park. In a May 14 story in the Los Angeles Times (several other southern California newspapers and TV web sites ran similar story), and live radio interviews on KPCC (Southern California Public Radio), KABC, and KFI (Los Angeles), Keeley indicated that postfire reseeding programs in southern California are expensive, have failed to guard against rainy season landslides, and introduce nonnative grasses whose establishment can in turn increase fire hazard, and that the strongest argument against seeding is that there are much more effective treatments such as hay bales and mulching that provide more reliable insurance against erosion. (Jon Keeley, Three Rivers, CA, 559-565-3170, jon_keeley@usgs.gov)

Demise of Repatriated Populations of Mountain Yellow-legged Frogs in the Sierra Nevada of California: Chytrid fungus and/or contaminants may have played a role in declines in mountain yellow-legged frogs in the Tableland area of Sequoia National Park, according to a recent publication in Herpetological Conservation and Biology by scientists of the U.S. Geological Survey and Environmental Protection Agency. In the late 1970s, the mountain yellow-legged frog was common in the Tableland area of Sequoia National Park in the Sierra Nevada of California. Surveys in 1993-1995 demonstrated that this frog had disappeared from this and other areas, even though the species was still common 30 km to the northeast. To evaluate potential causes of their disappearance, in 1994 and 1995 researchers repatriated mountain yellow-legged frog eggs, tadpoles, subadults, and adults to four previously occupied sites in the Tableland area and surveyed them through 1997. Within 12 months, all life history stages had disappeared at three sites, and at the fourth site there was limited reproduction, insufficient to maintain a population. Dispersal, weather, water quality, and predation did not appear to be causative agents. While the evaluation did not identify the specific cause for either the original or subsequent loss of the frog in the Tableland area, observations and data are consistent with chytridiomycosis, caused by the chytrid fungus Batrachochytrium dendrobatidis, and/or exposure to airborne pesticides as a primary cause of the decline. At the time of this study, however, chytridiomycosis had not yet been described and the potentially significant role of contaminants was largely undocumented. (Gary Fellers, Pt. Reyes, CA, 415-464-5185, gary_fellers@usgs.gov) Citation: Fellers, G. M., D. F. Bradford, D. Pratt, and L. Long Wood. 2007. Demise of repatriated populations of mountain yellow-legged frogs (Rana muscosa) in the Sierra Nevada of California. Herpetological Conservation and Biology 2(1): 5-21.

Climate Change and National Parks: USGS scientist Nate Stephenson was interviewed by Backpacker magazine for an upcoming article on the observed effects of climatic changes in national parks. (Nate Stephenson, Three Rivers, CA, 559-565-3176, nstephenson@usgs.gov)