ECOPHYSIOLOGY OF TROPICAL RHODOPHYTES. II. MICROSCALE ACCLIMATION IN PHOTOSYNTHESIS.

Beach, Kevin S.; Smith, Celia M.

Parameters of photosynthesis, vs. irradiance curves varied markedly between tissues from microsites along the <10-cm axes of the tropical intertidal red algae Ahnfeltiopsis concinna (J. Ag) Silva et DeCew and Laurencia mcdermidiae (f. Ag.) abbbott. Differences in photosynthetic performance between tissues from canopy and understory microsites indicated that L. mcdermidiae exhibited n expected sun to shade acclimation but over the space of <10cm. Respiration, I, I and P[submax] values were significantly lower in tissues from the understory relation to tissues from the canopy of L. mcdermiiae, while photosystem 1 (Ps 1) sizes (PSU 1) sizes (PSU 1) were significantly higher on tissues from understory microsites. Quantum efficiency was unchanged. Ahnfeltiopsis concinna, in contrast, exhibited higher a in tissues from understory rather than canopy microsites. The values of P[submax] for tissues from the canopy of A. concinna were not higher than the understory, while PSU O2(PS II size) of tissues from canopy microsites were unusually higher than those of understory microsites. These characteristics suggest a high degree of irradiance stress in tissues from the canopy of A. concinna, the hightest tidal alga in Hawaiian coastal zones. Acclimation to high photosynthetically active radiation and ultraviolet irradiance levels especially in tropical regions appears to be an essential mechanism(s) for stress resistance and persistence of interfidal algae. Algal turfs acclimate at microscales in part fostered by their dense stands that create sharp irradiance gradients as well as adjust physiologically to canopy irradiance levels as mechanisms for optimal photosynthetic performance and stress tolerance.

ALGAE; LAURENCIA; PHOTOSYNTHESIS; TISSUES; BIOLOGICAL pigments; ECOPHYSIOLOGY

Journal of Phycology, 1996, Vol 32, Issue 5, p710

0022-3646

Academic Journal

10.1111/j.0022-3646.1996.00710.x