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Publication
Posidonia oceanica photosynthesis along a depth gradient
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Advisor(s)
Abstract(s)
Seagrass photosynthetic rates depend largely on light availability, along with other environmental factors
and the physiological condition of the plants. Along a vertical gradient, seagrasses are permanently
exposed to distinct light environments, to which the photosynthetic apparatus must adapt. In this study, the
response of Posidonia oceanica photosynthesis to light was investigated in plants collected at three different
depths (3, 20 and 30m) in the Bay of Revellata, Corsica, France, in the the marine research station Stareso
(42º34’4’’N, 8º43’2’’E) in October, 2011. Photosynthesis-irradiance curves (P-I) were measured in an
oxygen electrode system (DW3/CB1, Hansatech). Photosynthetic rates were determined over an increasing
range of irradiance values, from darkness to 850 µmol quanta m-2 s-1. The Jassby and Platt hyperbolic
model (1957) equation was fitted to the obtained data, to calculate the relevant photosynthetic parameters.
For each depth, maximum photosynthetic rate (Pmax), inicial slope (), light saturation point (Ik), light
compensation point (Ic) and dark respiration (Rd) were determined. Photosynthetic parameters showed
significant variations with depth, particularly between the shallowest plants (3m) and the two other depths.
As expected, P. oceanica from 3m depth revealed a “sun-adapted” photosynthetic behavior in contrast with
plants from deeper waters.
Description
Keywords
Seagrass Posidonia oceanica Photosynthesis Depth gradient Light
Citation
Costa MM, Silva J, Olivé I, Barrote I, Santos R (2012). Posidonia oceanica photosynthesis along a depth gradient, 3rd Mediterranean seagrass workshop (May 2012), Essaouira, Morocco, p.26