THE SIGNIFICANCE OF INTRACELLULAR SELF-SHADING ON THE BIOOPTICAL PROPERTIES OF BROWN, RED, AND GREEN MACROALGAE

The spectral light absorption and fluorescence excitation spectra from thalli (in vivo) and thylakoid micelles (no intracellular self-shadin g) from the macroalgae Laminaria digitata (L.) Edmonson, Palmaria palm ata (L.) Kuntze, and Ulva sp. were examined. In all the examined speci es, the intracellular self-shading (i.e. the package effect) was highl y significant to the extent that absorption peaks related to individua l pigments were significantly suppressed. Thus, for studies related to taxonomy and physiology, ''unpacked'' spectra may be more informative . Thylakoid micelle preparations offer opportunities to examine more c losely species-specific differences in the packaging effect, light har vesting and utilization, and pigmentation. As well, the thylakoid mice lles, when analyzed with biochemical assays or fluorometry, may provid e insight into components of the photosynthetic machinery that are spe cific to different classes Of macroalgae. We present the Chi a-specifi c absorption coefficients and the corresponding fluorescence excitatio n spectra of macroalgal thylakoid micelles for the three species.