Effects of an Aquatic Herbicide Tank Mix on Metamorphic Northern Red-legged Frogs

Transcription

1 Effects of an Aquatic Herbicide Tank Mix on Metamorphic Northern Red-legged Frogs Amy Yahnke* Christian Grue*, Marc Hayes, and Schuyler Pearman-Gillman* Invasive Plants Conference 17 September 2014 Seattle, Washington *University of Washington Washington Department of Fish and Wildlife

2 Overview Herbicides are used in wetland restoration kingcounty.gov/weeds

3 Overview Are there risks to amphibians? kingcounty.gov/weeds

4 Triclopyr TEA Tank Mix ecologyadventure2.edublogs.org/plant/purple-loosestrife/ What is the best timing of application? ecologyadventure2.edublogs.org/plant/purple-loosestrife/ Infestation in Netley-Libau Marsh, Manitoba,

5 Amphibians Who s at risk? Late June-August

6 Metamorphosis A whole different ball game in toxicology Timing or (Howe et al. 2004, Cauble & Wagner 2005 ) Mortality (Greulich & Pflugmacher 2003) No food (Chen et al. 2008) Increased stress (Glennemeier & Denver 2002)

7 What are the effects of a triclopyr tank mix on metamorphic northern red-legged frogs? kingcounty.gov/weeds

8 Methods Tank mix \ cm water

9 Methods Triclopyr tank mix: \ 47.1 ppm ppm ppm

10 Methods 96 h static renewal Control (clean water) \ X 15

11 Methods 60-d grow out Control (clean water) \ Tankmix (clean water) X 15

12 Methods Endpoints

13 Results - overall No treatment-related mortalities No gross anomalies in gonad structure No treatment-related anomalies in over-all health

14 Results behavior during exposure Metamorphs showed evidence of stress during exposure to the tank mix # Observations Frogs Legs sprawled Control 2 2 Tank mix P = 0.013

15 Proportion of time on squares Results behavior post-exposure Metamorphs didn t care what color square they were on Black White P > 0.75 X c2 = CONTROL TANK MIX

16 Time (sec) Results behavior post-exposure Controls crawled more than tank mix metamorphs T/S T/C T S Turn/swim Turn/crawl Turn Swim 10 5 P = M-W U P C B In-place Crawl Burst 0 Control Tankmix

17 Days Results development timing Tank mixes took longer to complete metamorphosis t-test P = control tank mix

18 Body Condition Results body condition Body condition was not statistically different at 96 h control Tank mix 0.5 t-test on Δ P = Days

19 Body Condition Results body condition Metamorphosis complete d post-metamorphosis Control Tank mix Days

20 # Frogs Results feeding behavior Everyone started eating at the same time 5 4 Control Tankmix Days post-metamorphosis

21 Mean cumulative crickets eaten Results feeding behavior Everyone ate the same amount CONTROL TANK MIX Days since metamorphosis LMM day 53, P = 0.199

22 Mean cumulative crickets eaten Results feeding behavior Pre-existing limb deformities made it harder for tank mix metamorphs No limb deformities Limb deformities Control Improvement over simple model: LMM X 2 1= 3.99, P < 0.05; 64% of variance explained by interaction of treatment with limb deformities Tankmix

23 Liver Condition Results liver condition Everyone had the same liver condition t-test P = Control Tank mix

24 Results liver histology Control Tank mix

25 Summary Minimal effects observed Potential interaction with stressors

26 Conclusions Triclopyr can be a little stressful, but NRLF metamorphs get over it What is the real exposure in the field; is the risk acceptable? This information is important for informing policy and the public

27 UW PhD Committee Thank you! C Grue; D Beauchamp, E Faustman, M Hayes, A Wirsing Washington Department of Ecology, Aquatic Weeds Management Grants Washington Department of Fish and Wildlife M Hayes, D Heimer, T Hicks, C Roberts, K Tidwell, J Tyson UW Hatchery & UW Veterinarian Services J Wittouck Dr. G Sanders Washington Cooperative Research Unit, University of Washington R Fisk, JM Grassley, C Grue, S Pearman-Gillman, M Smith, A Troiano School of Aquatic & Fishery Sciences SePro Woodland Park Zoo

28 Questions?

29 Liver histology Lesion Severity #Lesions per 20x field Control Tankmix Total # frogs mild mild to moderate moderate moderate to severe severe