Effects of ultraviolet radiation on toad early life stages
Tóm tắt
Exposure to harmful levels of ultraviolet-B radiation (UVB), a component of solar radiation, has been suggested as a potential cause of amphibian declines. We measured solar radiation (UVB, ultraviolet-A, and visible) wavebands in breeding ponds of Bufo boreas (boreal toad, a montane species that has undergone severe population declines) and Bufo woodhousii (Woodhouse’s toad, a plains toad that has not experienced declines) and examined tolerances of these species to simulated solar UVB exposures in the laboratory. We found larvae of both species to be tolerant of simulated solar UVB in excess of solar UVB levels observed in their breeding ponds. B. boreas tadpoles were more tolerant of simulated solar UVB exposure than B. woodhousii tadpoles, possibly because of greater amounts of photoprotective melanin in B. boreas skin. UVB levels observed in B. boreas habitats do not currently appear to constitute a threat to the survival of these animals; however, long-term (>1 month) exposure to UVB levels comparable to levels associated with the water interface appears to reduce survival in B. woodhousii tadpoles. Therefore, future increases in surface and water column UVB radiation in bufonid habitats might pose significant survival risks to B. boreas or B. woodhousii populations.
Tài liệu tham khảo
APHA (American Public Health Association), American Water Works Association and Water Pollution Control Federation (1992): Standard Methods for the Examination of Water and Wastewater. 20th Edition. APHA, Washington, DC
Blaustein AR, Hoffman PD, Hokit DG, Kiesecker JM, Walls SC, ] Hays JB (1994a): UV repair and resistance to solar UVB in amphibian eggs: A link to population declines? Proceedings of the National Academy of Sciences 91: 1791–1795
Blaustein AR, Hokit DG, O’Hara RK, Holt RA (1994b): Pathogenic fungus contributes to amphibian loses in the Pacific Northwest. Biological Conservation 67: 251–254
Blaustein AR, Kiesecker JM, Shivers DP, Hokit DG, MarcoA, Beiden LK, HatchA (1998): Effects of ultraviolet radiation on amphibians: Field experiments. American Zoologist 38:799–812
CareyC (1993): Hypothesis concerning the causes of the disappearance of boreal toads from the mountains of Colorado. Conservation Biology 7: 355–362
Carey C, Little EE, Calfee RD, Middleton EM, Blazer V, Fetkavitch C (in preparation): Sensitivities of tiger salamander (Ambystoma tigrinum) eggs and larvae to ultraviolet radiation. Conservation Biology
Cleveland L, Little EE, Ingersoll CG, Wiedmeyer RH, Hunn JB. (1991): Sensitivity of brook trout to low pH, low calcium, and elevated aluminum concentrations during laboratory pulse exposures. Aquatic Toxicology 19: 303–318
Corn PS (1998): Effects of ultraviolet radiation on boreal toads in Colorado. Ecological Applications 8:18–26
Cummins CP, Greenslade PD, McLeod AR (1999): A test of the effect of supplemental UV-B radiation on the common frog, Rana temporaria L. during embryonic development. Global Change Biology 5: 471–479
Deutschlander ME, Phillips JB (1995): Characterization of an ultraviolet photoreception mechanism in the retina of an amphibian, the axolotl (Ambystoma mexicanum). Neuroscience Letters 197: 93–96
Dunnett CW (1955): A multiple comparisons procedure for comparing several treatments with a control. Journal of the American Statistical Association 50: 1096–1121
Fabacher DL, Little EE (1995): Skin component may protect fishes from ultraviolet-B radiation. Environmental Science and Pollution Research 2: 30–32
Fabacher DL, Little EE (1998): Photoprotective substance occurs primarily in outer layers of fish skin. Environmental Science and Pollution Research 5: 4–6
Gosner KL (1960): A simple table for staging embryos and larvae with notes on identification Herpetologica 16:183–190
Grant KP, Licht LE (1995): Effects of ultraviolet radiation on life-history stages of anurans from Ontario, Canada. Canadian Journal of Zoology 73,2292–2301
Hansen LJ, Fabacher DL, CalfeeR (2001): The role of the egg jelly coat in protecting Hyla regilla and Bufo canorus embryos form ultraviolet B radiation during development. Environmental Science and Pollution Research 8:1–5
Hawryshyn CW (1992): Polarization vision in fish. American Scientist 80:164–175
Hays JB, Blaustein AR, Kiesecker YM, Hoffman PD, PandelovaI, Coyle D, RichardsonT (1996): Developmental responses of amphibians to solar and artificial UVB sources: A comparative study. Photochemistry and Photobiology 64,449–456
Herman JR, Celarier E, LarkoD (2001): UV 380 nm reflectivity of the Earth’s surface, clouds and aerosols. J. Geophysical Research 106 (D6): 5335–5351
Herman JR, Krotkov N, Celarier E, Larko D, LobowG (1999): Distribution of UV radiation at the earth’s surface from TOMS-measured UV-backscattered radiances. Journal of Geophysical Research 104 (DUO): 12,059–12,076
Keisecker JM, Blaustein AR, Beiden LK (2001): Complex causes of amphibian population declines Nature 410:681–684
Lean, DRS (1997): Influence of ultraviolet-B radiation on aquatic ecosystems. In: Environmental toxicology and risk Assessment: Vol 7. ASTM STP 1333 (ed LittleE), pp 1–20, American Society for Testing and Materials,West Conshohocken, Pennsylvania
Little EE, Calfee R, Cleveland L, Skinker R, Zaga-ParkhurstA, and Barron MG. (2000): Photo-Enhanced toxicity in amphibians: Synergistic interactions of solar ultraviolet radition and aquatic communities. Journal of the Iowa Academy of Sciences 107: 67–71
Little EE, Fabacher DL (1996): Exposure of freshwater fish to simulated solar UV-B radiation. In: Techniques in Aquatic Toxicology (ed Ostrander GL), ppl41–158. Lewis Publishers, Boca Raton, Florida
Little EE, Fabacher DL (1994): Comparative sensitivity of rainbow trout and two threatened salmonids, Apache trout and Lahontan cutthroat trout, to ultraviolet-B radiation. Archiv fur Hydrobiologie Beiheft 43:217–226
Middleton EM, Herman JR, Celarier EA, Wilkinson JW, Carey C, and Rusin RJ (2001): Evaluating ultraviolet radiation exposure with satellite data at sites of amphibian declines in Central and South America. Conservation Biology 15: 914–929
Ovaska K, Davis TM, Flamarique IN (1997): Hatching success and larval survival of the frogs Hyla regilla and Rana aurora under ambient and artificially enhanced solar radiation. Canadian Journal of Zoology 75: 1081–1088
Skully NH, Lean DRS (1994): The attenuation of ultraviolet radiation in temperate lakes. Archiv fur Hydrobiologie Beiheft. 43: 135–144
Tevini M. (1993): Effects of enhanced UV-B radiation on terrestrial plants. IN: M Tevini (editor) UV-B Radiation and Ozone Depletion. Lewis Publishers, Boca Raton, Florida, pp 125–154
Zaga A, Little EE, Rabeni CF, Ellersieck MR (1998): Photoenhanced toxicity of a carbamate insecticide to early life stage amphibians. Environmental Toxicology and Chemistry 17: 2022–2035