J. Orduña-Rojas, D. Robledo, C. J. Dawes
Studies on the Tropical Agarophyte Gracilaria cornea J. Agardh (Rhodophyta, Gracilariales) from
Yucatán, Mexico.
I. Seasonal Physiological and Biochemical Responses
Photosynthetic performance, photosynthetic pigments, carbohydrate and protein content were measured monthly in Gracilaria cornea collected over 1 year in Yucatán, Mexico. The algae showed a marked seasonality in photosynthetic capacity and biochemical constituents. The photosynthetic rates (4 to 11 mg O2 g d wt?1 h?1) were higher during the cold (November–February) and dry (March–June) seasons compared to the wet (June–October) season. Compensation and saturation irradiances were low (17–37 and 72–155 ?mol photons m?2 s?1). Thus, although the populations occurred in shallow (2–4 m) water, the low light acclimation reflects the effect of high turbidity, sedimentation on the branches, and low irradiance values that were continuously recorded (1.97 to 8.85 mol photons m?2 d?1) throughout the year. The low concentrations of chlorophyll a (0.25 to 0.49 mg g d wt?1) and phycoerythrin (0.03 to 0.25 mg g d wt?1) reflect the oligotrophic waters as shown by concentrations of dissolved inorganic nitrogen (9.1 ?mol L?1) and dissolved reactive phosphate (0.5 ?mol L?1). Total soluble carbohydrate levels increased from July to October reaching 56% (dry weight basis) coinciding with high water temperatures. Protein levels ranged from 5.1% in February to 3.0% (dry weight basis) in August with no significant differences between months. Thus, the growth period for Gracilaria cornea appears to be temperature limited, occurring mainly during the dry seasons.
Botanica Marina, Walter de Gruyter
Print ISSN: 0006-8055
Volume: 45, 09/2002
Pages: 453 - 458
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