Synergistic effects of ultraviolet radiation and conditions at low tide on egg masses of limpets (<Emphasis Type="Italic">Benhamina obliquata</Emphasis> and <Emphasis Type="Italic">Siphonaria australis</Emphasis>) in New Zealand |
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Authors: | Janine Russell Nicole E Phillips |
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Institution: | (1) School of Biological Sciences and Coastal Ecology Laboratory, Victoria University of Wellington, P.O. Box 600, Wellington, New Zealand;(2) Present address: Ministry for the Environment, P.O. Box 1362, Wellington, New Zealand |
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Abstract: | The effects of ultraviolet radiation (UVR), desiccation and conditions in tidal pools on embryonic survival were examined
for two common pulmonate limpets that lay intertidal benthic egg masses on rocky shores in New Zealand: Benhamina obliquata and Siphonaria australis. Field surveys and manipulative experiments were conducted between December 2006 and September 2007 in the Wellington region
of New Zealand (41°17′S, 174°47′E). Egg mass deposition sites in the field were species-specific: B. obliquata deposited eggs primarily in shaded crevices, whereas S. australis predominantly deposited egg masses in the sun and in tidal pools. For both species, however, embryonic mortality was greater
in egg masses that had been in full sun compared to shade. For S. australis, there was also high mortality in egg masses in tidal pools or desiccated compared to those that remained submerged in flowing
seawater at low tide. In outdoor experiments, embryonic mortality was also always greatest for egg masses exposed to full
sun, and lowest for those in shaded treatments. Mortality was also higher if egg masses were in simulated tidal pools, and
for S. australis, if desiccated, compared to those submerged in flowing seawater. Periods of particularly sunny conditions with high temperatures
also resulted in higher overall mortality. Finally, egg masses of both species that were initially deposited in the shade had greater mortality in response to subsequent
UV exposure compared to egg masses initially deposited in full sun. Results from this study suggest that the egg masses of
these two species are highly vulnerable to UVR, as well as other intertidal stressors. Embryos of both of these species may
be at risk of high mortality particularly during summer when extreme conditions of UV intensity and high temperature coincide
with low tide cycles.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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