Response of the tropical red seaweed Gracilaria cornea to temperature, salinity and irradiance |
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Authors: | CJ Dawes J Orduña-rojas D Robledo |
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Institution: | (1) Department of Biology, University of South Florida, Tampa, Florida, 33620, U.S.A;(2) Centro de Investigacion y de Estudios Avanzados del I.P.N. Unidad Mérida, A.P. 73 Cordemex, 97310 Yucatan, Mexico |
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Abstract: | The agarophyte Gracilaria cornea, collected over 2.5 y in the Florida Keys, shows adaptations to oceanic salinities and subtropical
to tropical water temperatures in its photosynthetic and respiratory responses as measured with a respirometer. No seasonal
pattern in responses to irradiance, temperature, and salinity were evident between five collections over a 20-month period,
indicating the tropical nature of the populations from Bahia Honda and Pigeon Keys. Concentrations of chlorophyll a (0.09
to 0.41 mg g d wt-1) and phycoerythrin (0.06 to 0.36 mg g d wt- 1) were low and reflect the low nutrient regime of the habitats,
especially when compared to laboratory cultured plants. Compensation and saturation irradiances were also low (11–38 and 90–127
μmol photon m-2 s-1), indicating acclimation to lower irradiances in their shallow (1–2 m depth) habitats where turbidity
can be high. In comparison with other subtropical and warm temperate species of Gracilaria, G. cornea had lower levels of
pigment, but similarly high photosynthetic efficiency, demonstrating shade adaptation; it had only limited tolerance to salinities
below 20‰ and temperatures below 15 °C. Thus, G. cornea from the Florida Keys in mariculture would require subtropical to
tropical temperatures and stable oceanic salinities.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | Gracilaria cornea photosynthesis respiration chlorophyll phycoerythrin Florida salinity temperature irradiance |
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