Does simultaneous UV-B exposure enhance the lethal and sub-lethal effects of aquatic hypoxia on developing anuran embryos and larvae?
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Recent catastrophic global amphibian declines have been partially linked to increases in UV-B radiation as a consequence of stratospheric ozone depletion. Previous studies have shown that in the presence of other environmental stressors including aquatic pH and temperature and the presence of contaminants or pathogens, the lethal effects of UV-B on amphibian larvae are enhanced due to interactions between the stressors. Little is known about the interactions between UV-B and aquatic hypoxia, a common and significant natural stressor of amphibian larvae. We examined the potential effects of UV-B and aquatic hypoxia in combination on embryonic survival, developmental rate, body mass and locomotor performance of embryos and larvae of the striped marsh frog, Limnodynastes peronii. We found that while both UV-B and hypoxia independently had substantial negative effects on the developing embryos of L. peronii, they did not interact in a multiplicative or antagonistic manner. The effects of the stressors in combination were as might be predicted based on the knowledge of their independent actions alone (i.e. an additive effect). In all cases developing embryos exposed to both UV-B and hypoxia were more severely affected than those exposed to either UV-B or hypoxia alone. The results of this study show the importance of examining both the direct actions of individual stressors and how these may be influenced by the presence of other environmental factors.
KeywordsConservation physiology Frogs Amphibian declines Synergistic Tadpoles Ultraviolet radiation
This research was funded by an Australian Endeavour Postdoctoral Research Fellowship (ERF_PDR_1210_2009) to MHB, and El Departamento Administrativo de Ciencia, Tecnología e Innovación de Colombia COLCIENCIAS travel grant (to MHB) and The University of Queensland (CEF). The authors thank Toby Mitchell and Dan Hancox for assistance with this research. Frog collection and experimentation was approved by EPA Queensland (WISP 05523208) and The University of Queensland Animal Welfare Unit (SIB/626/08/URG).
- Ankley GT, Diamond SA, Tietge JE, Holcombe GW, Jensen KM, DeFoe DL, Peterson R (2002) Assessment of the risk of solar ultraviolet radiation to amphibians. I. Dose-dependent induction of hindlimb malformations in the Northern leopard frog (Rana pipiens). Environ Sci Technol 36:2853–2858. doi: 10.1021/es011195t PubMedCrossRefGoogle Scholar
- Anstis M (2002) Tadpoles of south-eastern Australia: a guide with keys. New Holland in association with the World Wide Fund for Nature, Frenchs Forest, NSW, p 281Google Scholar
- Blaustein AR, Belden LK, Hatch AC, Kats LB, Hoffman PD, Hays JB, Marco A, Chivers DP, Kiesecker JM (2001) Ultraviolet radiation and amphibians. In: Cockell CS, Blaustein AR (eds) Ecosystems, evolution and ultraviolet radiation. Springer, New York, pp 63–79Google Scholar
- Bradford DF, Seymour RS (1988) Influence of water potential on growth and survival of the embryo, and gas conductance of the egg, in a terrestrial breeding frog, Pseudophryne bibroni. Physiol Zool 61:470–474Google Scholar
- Burggren WW, Feder ME, Pinder AW (1983) Temperature and the balance between aerial and aquatic respiration in larvae of Rana berlandieri and Rana catesbeiana. Physiol Zool 56:263–273Google Scholar
- Gosner KL (1960) A simplified table for staging anuran embryos and larvae with notes on identification. Herpetologiea 16:183–190Google Scholar
- Licht LE, Grant KP (1997) The effects of ultraviolet radiation on the biology of amphibians. Am Zool 37:137–145Google Scholar
- Long LE, Saylor LS, Soule ME (1995) A pH/UV-B synergism in amphibians. Conserv Biol 9:1301–1303Google Scholar
- Mckinlay AF, Diffey BL (1987) A reference action spectrum for ultraviolet-induced erythema in human skin. In: Passchier WF, Bosnajakovic BFM (eds) Human exposure to ultraviolet radiation: risks and regulations. Elsevier, Amsterdam, pp 83–87Google Scholar
- Mendelson JR, Lips KR, Gagliardo RW, Rabb GB, Collins JP, Diffendorfer JE, Daszak P, Ibanez DR, Zippel KC, Lawson DP, Wright KM, Stuart SN, Gascon C, da Silva HR, Burrowes PA, Joglar RL, La Marca E, Lotters S, du Preez LH, Weldon C, Hyatt A, Rodriguez-Mahecha JV, Hunt S, Robertson H, Lock B, Raxworthy CJ, Frost DR, Lacy RC, Alford RA, Campbell JA, Parra-Olea G, Bolanos F, Domingo JJ, Halliday T, Murphy JB, Wake MH, Coloma LA, Kuzmin SL, Price MS, Howell KM, Lau M, Pethiyagoda R, Boone M, Lannoo MJ, Blaustein AR, Dobson A, Griffiths RA, Crump ML, Wake DB, Brodie ED Jr (2006) Biodiversity. Confronting amphibian declines and extinctions. Science 313:48. doi: 10.1126/science.1128396 Google Scholar
- Salthe SN, Duellman WE (1973) Quantitative constraints associated with reproductive mode in anurans. In: Vial J (ed) Evolutionary biology of the anurans: contemporary research on major problems. University of Missouri Press, Columbia, pp 229–249Google Scholar
- Seymour RS, Roberts JD (1991) Embryonic respiration and oxygen distribution in foamy and nonfoamy egg masses of the frog Limnodynastes tasmaniensis. Physiol Zool 64:1322–1340Google Scholar
- Seymour RS, Mahony MJ, Knowles R (1995) Respiration of embryos and larvae of the terrestrially breeding frog Kyarranus loveridgei. Herpetologica 51:369–376Google Scholar