The role of the egg jelly coat in protectingHyla regilla andBufo canorus embryos from ultraviolet B radiation during development

Hansen, Lara J.; Fabacher, David L.; Calfee, Robin D.

doi:10.1007/bf02987591

Cited by 12 publications

(4 citation statements)

References 16 publications

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“…However, other studies have found that melanin does not protect exposed animals from the damaging effects of UVBR (e.g., Belden and Blaustein 2002c). Hansen et al (2002) have shown that the egg mass jelly of Hyla regilla embryos displayed no absorption in the UVR range. Removal of the jelly coat of both H. regilla and Bufo canorus (Yosemite toad) embryos and subsequent exposure to UVBR in a solar simulator also demonstrated that the jelly played no apparent role in protecting embryos; hatching success was similar in eggs with and without the egg jelly (see also Rasanen et al 2003).…”

Section: Effects Of Uvbr Exposure On the Rate Of Amphibian Developmenmentioning

confidence: 96%

Global Increases in Ultraviolet B Radiation: Potential Impacts on Amphibian Development and Metamorphosis

Croteau

Davidson

Lean

et al. 2008

Physiological and Biochemical Zoology

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Levels of ultraviolet B radiation (UVBR) reaching the Earth's surface have increased since the 1970s as a result of stratospheric ozone depletion caused by the emission of ozone-depleting substances (ODSs) such as chlorofluorocarbons. Despite international agreements to phase out harmful ODSs, these substances are persistent, and even under the most optimistic scenarios, stratospheric ozone levels will not return to pre-1980 levels for several decades. Furthermore, climate change may enhance chemical stratospheric ozone depletion. Global phenomena such as climate change, ozone depletion, and acidification of aquatic ecosystems interact to modify dissolved organic carbon levels in aquatic systems, thereby increasing the penetration of UVBR. Since amphibians inhabit both aquatic and terrestrial habitats and have unshelled eggs and permeable skin, they are vulnerable to changes in environmental conditions and habitat quality. Increased exposure of amphibians to UVBR can produce lethal and sublethal effects, especially in individuals that do not possess adequate defense mechanisms to protect themselves. In this article, we discuss worldwide increases in UVBR and the adverse effects of UVBR exposure on amphibians. Specifically, studies on the effects of UVBR on amphibian development and metamorphosis are summarized, and possible mechanisms of thyroid system disruption caused by UVBR exposure are considered.

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Section: Effects Of Uvbr Exposure On the Rate Of Amphibian Developmenmentioning

confidence: 96%

Global Increases in Ultraviolet B Radiation: Potential Impacts on Amphibian Development and Metamorphosis

Croteau

Davidson

Lean

et al. 2008

Physiological and Biochemical Zoology

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“…Perotti and Diéguez [92] also found that the optical properties of the egg jelly envelope surrounding the embryo is also correlated with embryonic melanin concentration: the egg jelly of the species with the lowest embryonic melanin concentration (P. thaul) had the highest UVR absorbance whereas the egg jelly of the species with the highest embryonic melanin concentration (R. spinulosa) had the lowest UVR absorbance. Several additional studies have similarly shown that the UVR absorbance by the egg jelly envelope varies with wavelength and among species [93][94][95][96][97], and also the protective role of the jelly envelope varies among populations within a species along an elevation gradient [98]. Such research indicates that for some species the jelly envelope may provide adequate protection against UVR for the embryo, whereas others may rely on alternative defence strategies such as pigmentation, behavioural avoidance (e.g.…”

Section: Uvr-screening Compounds and Egg Jellymentioning

confidence: 97%

Drivers of amphibian declines: effects of ultraviolet radiation and interactions with other environmental factors

Alton

Franklin

2017

Clim Chang Responses

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As a consequence of anthropogenic environmental change, the world is facing a possible sixth mass extinction event. The severity of this biodiversity crisis is exemplified by the rapid collapse of hundreds of amphibian populations around the world. Amphibian declines are associated with a range of factors including habitat loss/ modification, human utilisation, exotic/invasive species, environmental acidification and contamination, infectious disease, climate change, and increased ultraviolet-B radiation (UVBR) due to stratospheric ozone depletion. However, it is recognised that these factors rarely act in isolation and that amphibian declines are likely to be the result of complex interactions between multiple anthropogenic and natural factors. Here we present a synthesis of the effects of ultraviolet radiation (UVR) in isolation and in combination with a range of naturally occurring abiotic (temperature, aquatic pH, and aquatic hypoxia) and biotic (infectious disease, conspecific density, and predation) factors on amphibians. We highlight that examining the effects of UVR in the absence of other ecologically relevant environmental factors can greatly oversimplify and underestimate the effects of UVR on amphibians. We propose that the pathways that give rise to interactive effects between multiple environmental factors are likely to be mediated by the behavioural and physiological responses of amphibians to each of the factors in isolation. A sound understanding of these pathways can therefore be gained from the continued use of multi-factorial experimental studies in both the laboratory and the field. Such an understanding will provide the foundation for a strong theoretical framework that will allow researchers to predict the combinations of abiotic and biotic conditions that are likely to influence the persistence of amphibian populations under future environmental change.

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“…The absorption maximum of the jelly was at 275 nm in various anuran species (Ovaska et al 1997). Hansen et al (2001) noticed that efficient protection against UV-B would require a maximum UV-B absorption between 294 and 305 nm, which represents the most deleterious range of UV-B wavelengths. In lower UV-B doses than those used in our experiments, the jelly did not play an apparent role in photoprotection in R. temporaria (Räsänen et al 2003), Hyla regilla, or Bufo canorus (Hansen et al 2001).…”

Section: Discussionmentioning

confidence: 99%

Developmental responses to UV‐B radiation in common frogRana temporariaembryos from along an altitudinal gradient

2008

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Solar ultraviolet radiation (UV) is harmful for developing amphibians. As UV increases with altitude and latitude, it is suggested that high altitude and latitude populations have evolved tolerance to high levels of UV.Using laboratory experiments, we tested the hypothesis that Rana temporaria populations from several altitudes (438-2,450 m above sea level) were adapted to UV by assessing the effects of artificial UV on embryos mortality rate, malformations, and body length at hatching. We also tested the protective role of the jelly surrounding the embryos. Without artificial UV exposure, hatching success decreased with altitude of the population. Malformation rates were low for all populations (mean 1.36%), and hatching size increased with altitude. The artificial UV (UV-B, UV-A, and visible) used was similar to the solar spectrum received at high altitude. Exposed embryos had performance similar to that of embryos without exposure: a decreased hatching success with altitude and a low malformation rate (mean 0.85%). However, hatching size did not vary with altitude, and UV-exposed embryos tended to be smaller at hatching than non-exposed embryos. Removal of the protective jelly envelope greatly decreased the performance of UVexposed embryos: hatching success strongly decreased with altitude and embryos of the highest population (2,450 m asl) did not develop. Malformation reached 4.98%, without population differences, and hatching size of embryos without jelly was smaller than hatching size of non-manipulated embryos with no population effect. This study demonstrates that lowland jellyless embryos were less sensitive (i.e., exhibited a higher survival rate) than highland embryos and, on the other hand, that the jelly envelope was a more efficient protection for embryos in highland than in lowland populations. A trade-off hypothesis is presented to explain this difference in UV tolerance and protection among populations: in a harsh, highland environment (i.e., with a curtailed activity period), embryos have to invest in development and growth and, thus, embryo protection should be a female investment (via the jelly). In a lowland environment, embryonic growth and development are less constrained and embryos are able to invest and use protection or repair mechanisms inherited from their parents.

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The role of the egg jelly coat in protectingHyla regilla andBufo canorus embryos from ultraviolet B radiation during development

Abstract: Based on the results in this study it seems unlikely that the egg jelly coat is playing a crucial role in protecting developing embryos from the impact of UVB radiation.

Cited by 12 publications

References 16 publications

Global Increases in Ultraviolet B Radiation: Potential Impacts on Amphibian Development and Metamorphosis

Global Increases in Ultraviolet B Radiation: Potential Impacts on Amphibian Development and Metamorphosis

Drivers of amphibian declines: effects of ultraviolet radiation and interactions with other environmental factors

Developmental responses to UV‐B radiation in common frogRana temporariaembryos from along an altitudinal gradient

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