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dc.contributor.authorVopel, K
dc.contributor.authorHawes, I
dc.date.accessioned2011-07-13T21:45:56Z
dc.date.available2011-07-13T21:45:56Z
dc.date.copyright2006-07-01
dc.date.issued2011-07-14
dc.identifier.citationLimnology and Oceanography, vol.51(4), pp.1801 - 1812
dc.identifier.issn0024-3590
dc.identifier.urihttp://hdl.handle.net/10292/1449
dc.description.abstractWe measured in situ photosynthesis of benthic microbial mats at various depths in Lake Hoare, a permanently ice-covered lake of the McMurdo Dry Valleys, Antarctica, using oxygen (02) microelectrodes. We further investigated the vertical distribution and activity of pigments in the microbial mats using an imaging pulse-amplitude-modulated fluorometer. Microbial mats to at least 16.6-m water depth are net producers Of 02 during the summer period. Net 02 production ranges from 100-500 mu mol m(-2) h(-1) at incident downwelling irradiances of photosynthetically active radiation (PAR) of 1.0-4.6 mu mol quanta m(-2) s(-1). Photosynthesis of mat-forming cyanobacteria and diatoms occurs at all lake depths at or close to maximum efficiency. We measured absorption by the pigment arrays at a single water depth and, by assuming that absorption is water-depth invariant, we estimated an area-specific maximum community quantum yield of 0.073 mol carbon per mol photons. A community compensation irradiance of 0.1 mu mol quanta m(-2) s(-1) was estimated, reflecting extreme shade acclimation. These results confirm estimates previously derived from laboratory gas-exchange measurements and imply that even minor changes in the intensity of the incident downwelling irradiance of PAR caused by, for example, changes in the transparency of the ice cover or the optical properties of the water column can significantly alter rates of benthic carbon fixation. In situ measurements were confined to mats with flat surfaces. Laboratory measurements at the surface of mats with pinnacled surfaces revealed a complex small-scale chemical structure at the mat-water interface.
dc.publisherAmerican Society of Limnology and Oceanography (ASLO)
dc.relation.urihttp://aslo.org/lo/toc/vol_51/issue_4/1801.html
dc.rights© 2006 by the American Society of Limnology and Oceanography, Inc. All Rights Reserved. (please see Citation and Publisher’s Version). Over 90% of articles published in the ASLO journals are in Free Access Publication (FAP). Non-FAP articles are available for download to subscribers only. All articles are moved into Free Access Publication after three years.
dc.subjectDry valley lakes
dc.subjectDiffusive boundary-layer
dc.subjectIce-covered lake
dc.subjectChlorophyll fluorescence
dc.subjectPam fluorometer
dc.subjectAlgal mats
dc.subjectPhytoplankton
dc.subjectSediments
dc.subjectLight
dc.subjectWater
dc.titlePhotosynthetic performance of benthic microbial mats in Lake Hoare, Antarctica
dc.typeConference Contribution
dc.rights.accessrightsOpenAccess
dc.identifier.doihttp://dx.doi.org/10.4319/lo.2006.51.4.1801


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