Effect of hyposalinity on the photophysiology of Siderastrea radians

Chartrand, Kathryn M., Durako, Michael Joseph, and Blum, James E. (2009) Effect of hyposalinity on the photophysiology of Siderastrea radians. Marine Biology, 156. pp. 1691-1702.

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Abstract

Tolerance to hyposalinity of the scleractinian coral S. radians was examined in a mesocosm study. Colonies of S. radians were collected from five basins in Florida Bay, USA, which occur along a northeast-to-southwest salinity gradient. Salinity treatments were based on historical salinity records for these basins. Photophysiology of the endosymbiont Symbiodinium spp. (maximum quantum yield; F (v)/F (m)) was measured as an indicator of holobiont stress to hyposalinity. Colonies from each basin were assigned four salinity treatments [The Practical Salinity Scale (PSS) was used to determine salinity. Units are not assigned to salinity values because it is a ratio and has no unit as defined by UNESCO (UNESCO Technical papers no. 45, IAPSO Pub. Sci. No. 32, Paris, France, 1985)] (30, 20, 15, and 10) and salinities were reduced 2 per day from ambient (30) to simulate a natural salinity decrease. Colonies treated with salinities of 20 and 15 showed no decrease in F (v)/F (m) versus controls (i.e. 30), up to 5 days after reaching their target salinity. This indicates a greater ability to withstand reduced salinity for relatively extended periods of time in S. radians compared to other reef species. Within 1 day after salinity of 10 was reached, there was a significant reduction in F (v)/F (m), indicating a critical threshold for hyposaline tolerance. At the lowest treatment salinity (10), F (v)/F (m) for the more estuarine, northeast-basin colonies were significantly higher than the most marine southwest-basin colonies (Twin Key Basin). Our results suggest that historical salinity ranges within basins determine coral population salinity tolerances.

Item ID: 31118
Item Type: Article (Research - C1)
ISSN: 1432-1793
Keywords: Thalassia testudinum, bleaching event, photosystem-II, Florida Bay, photosynthetic efficiency, scleractinian corals, elevated temperature, salinity stress, climate change, reef corals
Funders: Florida Fish and Wildlife Conservation Commission
Projects and Grants: Florida Fish and Wildlife Conservation Commission Grant No. 56980
Date Deposited: 30 Jan 2014 15:23
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060203 Ecological Physiology @ 70%
06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060705 Plant Physiology @ 20%
06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060701 Phycology (incl Marine Grasses) @ 10%
SEO Codes: 96 ENVIRONMENT > 9609 Land and Water Management > 960903 Coastal and Estuarine Water Management @ 50%
96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960507 Ecosystem Assessment and Management of Marine Environments @ 50%
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