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Dimethylsulfide and Coral Bleaching: Links to Solar Radiation, Low Level Cloud and the Regulation of Seawater Temperatures and Climate in the Great Barrier Reef

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American Journal of Climate Change 2017年第2期6卷 328-359页

作者： Graham Jones Mark Curran hilton swan Elisabeth Deschaseaux School of Environment Science and Engineering Southern Cross University Lismore NSW Australia Marine Ecology Research Centre Southern Cross University Lismore NSW Australia Antarctic Climate and Ecosystems Cooperative Research Centre Hobart Tasmania Australia Centre for Coastal Biogeochemistry Southern Cross University Lismore NSW Australia

Coral reefs produce atmospheric dimethylsulfide (DMSa) which oxidises to non-sea-salt (nss) sulfate aerosols, precursors of cloud condensation nuclei (CCN) and low level cloud (LLC), reducing solar radiation and regulating sea surface temperatures (SSTs). Here we report measurements of solar radiation, SST, LLC, DMS flux, , and rainfall before, during and after a major coral bleaching event at Magnetic Island in the central Great Barrier Reef (GBR). Measurements are compared with those made at the nearby fringing reef of Or-pheus Island where coral bleaching did not occur. Extreme solar radiation levels occurred from November to late January and could have reflected cloud radiative effects that increased downwelling of solar radiation. High levels of LLC often coincided with high periodic fluxes of DMS from the unbleached coral reef at Orpheus Island (e.g. 14 - 20 μmol·m-2·d-1), in direct contrast to the very low fluxes of DMS that were emitted from the bleached, human-impacted Magnetic Island fringing reef (nd-0.8 μmol·m-2·d-1) when SSTs were >30°C. Continuous SSTs measurements at the Magnetic Island reef revealed various heating and cooling periods, interspersed with stable SSTs. Cooling periods (negative climate feedback) ranged from -1°C to -3°C (7 day mean -1.6°C), and often seemed to occur during low tides, periodic pulses of DMS flux and LLC, keeping SSTs °C. In contrast warming periods of +1°C to +3°C (positive climate feedback, 7 day mean +1.52°C), seemed to occur during increasing tides, decreasing DMS flux and low to medium levels of LLC which increased solar radiation and caused SSTs over 30°C and corals to bleach. Alternation between these two states or types of feedback is indicated in this research and may be a function of enhanced scattering of solar radiation from nss-sulfate aerosols that originate from oxidation of DMSa produced from the coral reefs in the GBR. The net radiative forcing from clouds can be as high as four times as large as the radi

关键词： Dimethylsulfide Low Level Cloud Climate Feedback Coral Bleaching

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Behavioural and energetic consequences of competition among three overwintering swan(Cygnus spp.)species

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Avian Research 2021年第4期12卷 707-721页

作者： Kevin A.Wood Julia L.Newth Geoff M.hilton Eileen C.Rees Wildfowl&Wetlands Trust SlimbridgeGloucestershire GL27BTUnited Kingdom Centre for Ecology and Conservation/Environment and Sustainabil-ity Institute College of Life and Environmental SciencesUniversity of ExeterExeter TR109EZUnited Kingdom Department of Zoology University of CambridgeDowning StreetCambridge CB23EJUnited Kingdom

Background:Winter numbers of the northwest European population of Bewick's swans(Cygnus columbianus bewickii)declined recently by c.40%.During the same period,numbers of two sympatric and ecologically-similar congeners,the Mute swan(Cygnus olor)and Whooper swan(Cygnus cygnus)showed increases or *** has been suggested that these opposing population trends could have a causal relationship,as Mute and Whooper swans are larger and competitively dominant to Bewick's swans in foraging *** so,effects of competition of Mute and Whooper swans on Bewick's swans should be detectable as measurable impacts on behaviour and ***:Here,we studied the diurnal behaviour and energetics of 1083 focal adults and first-winter juveniles("cygnets")of the three swan species on their winter grounds in eastern *** analysed video recordings to derive time-activity budgets and these,together with estimates of energy gain and expenditure,were analysed to determine whether individual Bewick's swans altered the time spent on key behaviours when sharing feeding habitat with other swan species,and any consequences for their energy expenditure and net energy ***:All three swan species spent a small proportion of their total time(0.011)on aggressive interactions,and these were predominantly intraspecific(≥0.714).Mixed-effects models indicated that sharing feeding habitat with higher densities of Mute and Whooper swans increased the likelihood of engaging in aggression for cygnet Bewick's swans,but not for *** levels of interspecific competition decreased the time spent by Bewick's swan cygnets on foraging,whilst adults showed the opposite *** among low densities of conspecifics(swans spent more time on vigilance in the presence of higher densities of Mute and Whooper swans,whilst individuals within higher density Bewick's swan flocks showed the opposite ***,we found no evide

关键词： Avian behaviour Energy expenditure Ethology Interference competition Interspecific interactions Time activity budgets Video observations

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