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Physiological response of temperate microphytobenthos to freezing temperatures
Microphytobenthos (MPB) contributes up to half the primary production of estuaries. These microorganisms are sensitive to changes in sediment temperatures, particularly the extreme temperatures during exposure periods. This study investigates the physiological responses of MPB to freezing temperatures at two locations near Hobart, Tasmania during winter. Photosynthetic parameters were measured at 2 mm intervals to a depth of 10 mm. FV/FM values at three different distances from the shoreline at Kings Beach and Browns River in winter were between 0.584 and 0.617. rETRmax values were between 24.696 and 20.773. Maximum a values peaked in the subsurface rather than at the sediment surface. In vitro laboratory experiments (down to 258C) showed little difference in response between the control and treatment groups, indicating no apparent effects of short term freezing on the MPB. Little change in photosynthetic parameters in response to freezing was probably associated with the resistance of light-harvesting reactions to freezing temperatures, recovery of the plasmalemma integrity or cryoprotection. Sediment composition and species composition were similar at both sampling sites. Therefore, responses of MPB were not due to species and grain size composition.
History
Publication title
Journal of the Marine Biological Association of The United KingdomVolume
93Issue
8Pagination
2039-2047ISSN
0025-3154Department/School
Institute for Marine and Antarctic StudiesPublisher
Cambridge Univ PressPlace of publication
40 West 20Th St, New York, USA, Ny, 10011-4211Rights statement
Copyright 2013 Marine Biological Association of the United KingdomRepository Status
- Restricted