Synergistic effects of ultraviolet radiation and conditions at low tide on egg masses of limpets ( Benhamina obliquata a
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ORIGINAL PAPER
Synergistic eVects of ultraviolet radiation and conditions at low tide on egg masses of limpets (Benhamina obliquata and Siphonaria australis) in New Zealand Janine Russell · Nicole E. Phillips
Received: 28 July 2008 / Accepted: 2 December 2008 / Published online: 18 December 2008 © Springer-Verlag 2008
Abstract The eVects 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 Weld were species-speciWc: 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 Xowing 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
Communicated by J. P. Grassle. Electronic supplementary material The online version of this article (doi:10.1007/s00227-008-1109-6) contains supplementary material, which is available to authorized users. J. Russell · N. E. Phillips (&) School of Biological Sciences and Coastal Ecology Laboratory, Victoria University of Wellington, P.O. Box 600, Wellington, New Zealand e-mail: [email protected] Present Address: J. Russell Ministry for the Environment, P.O. Box 1362, Wellington, New Zealand
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 Xowing 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.
Introduction Ultraviolet radiation (UVR, 280–400 nm) can cause a range of deleterious eVects on aquatic organisms, with early life stages at particular risk (reviewed by Hader et al. 2007). For example, exposure to UVR inhibits photosynthesis and causes DNA damage to kelp zoospores (Wiencke et al. 2000). In yellow perch, 100% of eggs die when exposed to full solar UV (HuV et al.
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