Seasonal heterogeneity in the photophysiological response to air exposure in two tropical intertidal seagrass species

Petrou, K., Jimenez-Denness, I., Chartrand, K., McCormack, C., Rasheed, Michael, and Ralph, P. J. (2013) Seasonal heterogeneity in the photophysiological response to air exposure in two tropical intertidal seagrass species. Marine Ecology Progress Series, 482. pp. 93-106.

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Abstract

Photosynthesis, chlorophyll a fluorescence, leaf bio-optical properties and pigments were measured in 2 tropical intertidal seagrass species, Zostera muelleri ssp. capricorni and Halophila ovalis before, during and after air-exposure over a tidal cycle. Data were collected across 4 seasons (October and January—growing seasons; May and July—senescent seasons) to determine seasonal dynamics in physiological responses to air exposure. Both species showed clear light-dependent responses with a decline in photosynthetic efficiency and increased photoprotection during periods of combined maximum daily irradiance and air exposure for all seasons. In Z. muelleri ssp. capricorni there was a negative correlation between air-exposed effective quantum yield and light intensity, suggesting exposure was driving this decline. Conversely, sensitivity (decline in effective quantum yield of photosystem II) to increased irradiance dominated the response in H. ovalis, with no change in the magnitude of this response between air-exposed and submerged blades. The response to air exposure observed in Z. muelleri ssp. capricorni showed seasonal variation, with a greater decline in photosynthesis during the spring (October). Tidal exposure did not provide intertidal seagrasses a 'window' of photosynthetic respite (increase in photosynthesis) from high natural or anthropogenic turbidity. However, the periods immediately prior to and after exposure were important for providing an optimum period for net photosynthetic gain.

Item ID: 30200
Item Type: Article (Research - C1)
ISSN: 1616-1599
Keywords: seagrass, Zostera muelleri ssp capricorni, Halophila ovalis, chl a fluorescence, light-limitation, air exposure
Funders: Queensland Gas Corporation, Gladstone Ports Corporation Limited, Queensland Department of Agriculture, Fisheries and Forestry, Australian Research Council (ARC)
Projects and Grants: ARC (LP110200454)
Date Deposited: 13 Nov 2013 05:38
FoR Codes: 06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060705 Plant Physiology @ 50%
06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060701 Phycology (incl Marine Grasses) @ 50%
SEO Codes: 96 ENVIRONMENT > 9609 Land and Water Management > 960903 Coastal and Estuarine Water Management @ 60%
97 EXPANDING KNOWLEDGE > 970105 Expanding Knowledge in the Environmental Sciences @ 40%
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