ECOPHYSIOLOGY OF TROPICAL RHODOPHYTES. I. MICROSCALE ACCLIMATION IN PIGMENTATION.

Beach, Kevin S.; Smith, Celia M.

Microscale pigment adjustments to a tropical photosynthetically active radiation and ultraviolet (UV) environment by the interidal turf algae Ahnfeltiopsis cancinna (J. Ag.) Silva et DeCew and Laurencia medermidiae (J. Ag.) Abbott were promoted by thalli densities that self-shade the understory portions of the same diminutive axes. Tissues of A. concinna from canopy microsites had significantly reduced levels of phycoerythrin, phycocyanin, and allophyeocyanin compared to tissues from understory microsites. These alterations coupled with enhanced levels of carotenoid and UV-absorbing compounds in tissues from canopy compared to tissues from understory microsites indicated a pattern of remarkably sensitive photoacelimation over the ≤ 10-cm axes of these turf-forming rhodophytes. Microscale variation in the in vivo UV absobance capabilities for turfs of A.concinna and L. mcdermidiae was directly related to the amount of extractable UV-absorbing compounds. An in vivo absorbace signature at ≃ 345 nm appears to provide a method to quickly and accurately gauge the potential UV-shielding capacity of primary producers even at remarkably fine ecological scales. The capacity for highly responsive biochemical adjustments that result in marked canopy-understory distinctions coupled with a turf morphology may be crucial for macroalgal tolerance of physiological stresses associate with tropical intertidal zones. This responsive capacity allows for enhanced photoprotective mechanisms in tissues from canopy microsites while optimizing irradiance capture in deeply shaded tissues from understory microsites <10 cm away.

ALGAE; BIOLOGICAL pigments; ANIMAL coloration; ECOPHYSIOLOGY; PHOTOSYNTHETICALLY active radiation (PAR); PHOTOSYNTHESIS; ULTRAVIOLET radiation

Journal of Phycology, 1996, Vol 32, Issue 5, p701

0022-3646

Academic Journal

10.1111/j.0022-3646.1996.00701.x