title: Sensitivity and Acclimation of Three Canopy-Forming Seaweeds to UVB Radiation and Warming.
abstract: Canopy-forming seaweeds, as primary producers and foundation species, provide key ecological services. Their responses to multiple stressors associated with climate change could therefore have important knock-on effects on the functioning of coastal ecosystems. We examined interactive effects of UVB radiation and warming on juveniles of three habitat-forming subtidal seaweeds from Western Australia-Ecklonia radiata, Scytothalia dorycarpa and Sargassum sp. Fronds were incubated for 14 days at 16-30°C with or without UVB radiation and growth, health status, photosynthetic performance, and light absorbance measured. Furthermore, we used empirical models from the metabolic theory of ecology to evaluate the sensitivity of these important seaweeds to ocean warming. Results indicated that responses to UVB and warming were species specific, with Sargassum showing highest tolerance to a broad range of temperatures. Scytothalia was most sensitive to elevated temperature based on the reduced maximum quantum yields of PSII; however, Ecklonia was most sensitive, according to the comparison of activation energy calculated from Arrhenius' model. UVB radiation caused reduction in the growth, physiological responses and thallus health in all three species. Our findings indicate that Scytothalia was capable of acclimating in response to UVB and increasing its light absorption efficiency in the UV bands, probably by up-regulating synthesis of photoprotective compounds. The other two species did not acclimate over the two weeks of exposure to UVB. Overall, UVB and warming would severely inhibit the growth and photosynthesis of these canopy-forming seaweeds and decrease their coverage. Differences in the sensitivity and acclimation of major seaweed species to temperature and UVB may alter the balance between species in future seaweed communities under climate change.
authors.affiliation: Ocean College, Zhejiang University, Xihu District, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Xiao
authors.affiliation: UWA Oceans Institute and School of Plant Biology, University of Western Australia, Crawley, WA, Australia.
authors.forename: Thibaut
authors.initials: T
authors.lastname: de Bettignies
authors.affiliation: UWA Oceans Institute and School of Plant Biology, University of Western Australia, Crawley, WA, Australia.
authors.forename: Ylva S
authors.initials: YS
authors.lastname: Olsen
authors.affiliation: UWA Oceans Institute and School of Plant Biology, University of Western Australia, Crawley, WA, Australia.|Department of Global Change Research, IMEDEA (CSIC-UIB), Institut Mediterrani d'Estudis Avançats, Esporles, Spain.|Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
authors.forename: Susana
authors.initials: S
authors.lastname: Agusti
authors.affiliation: UWA Oceans Institute and School of Plant Biology, University of Western Australia, Crawley, WA, Australia.|Department of Global Change Research, IMEDEA (CSIC-UIB), Institut Mediterrani d'Estudis Avançats, Esporles, Spain.|Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Duarte
authors.affiliation: UWA Oceans Institute and School of Plant Biology, University of Western Australia, Crawley, WA, Australia.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wernberg
mesh_terms: D065638:Absorption, Radiation; D000064:Acclimatization / Q000528:radiation effects*; D018533:Biomass; D057231:Climate Change; D017753:Ecosystem; D012624:Seaweed / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects*; D013696:Temperature; D014466:Ultraviolet Rays / Q000009:adverse effects*