CHARACTERIZATION OF IN-VIVO ABSORPTION FEATURES OF CHLOROPHYTE, PHAEOPHYTE AND RHODOPHYTE ALGAL SPECIES

Despite the plentiful diversity of macroalgae in coastal environments, few studies have examined the in vivo absorption features of common m arine macrophytes. Here we report on results of a survey of 12 central California common intertidal and subtidal taxa, representing Chloroph yta, Phaeophyta and Rhodophyta carried out in the summer of 1988. Comp uter-assisted analyses were used to obtain fourth-derivative spectra f rom in vivo absorption spectra determined at room temperature to obtai n spectral diagnostics for the different algai divisions and to provid e a means to determine whether spectral features could be used to iden tify stress responses among these plants. Among the Chlorophyta, chara cteristic maxima for chlorophylls a and b were resolved in all species examined, and a spectral component attributable to siphonaxanthin-lik e carotenoid(s) was observed in two Ulva species and the coenocytic al ga Derbesia marina. Representatives of the Phaeophyta were characteriz ed by similar maxima for chlorophyll a and c, and for fucoxanthin. Amo ng the Rhodophyta, maxima for chlorophyll a, as well as B- and R-type phycoerythrin were resolved. Differences in in vivo absorption feature s were detected for two tidal populations of Porphyra perforata and Ma stocarpus papillatus. High-tidal thalli absorb less green light in reg ions characterized by phycoerythrin, but have enhanced carotenoid abso rption compared with low-tidal thalli. Resolution of spectra by fourth -derivative analysis revealed significant differences in phycoerythrin and carotenoid contents. The spectral changes observed appear to refl ect environmental and possibly populational characteristics of these a lgae. The spectral analyses described here provide robust, non-invasiv e means to characterize subtle responses of macroalgae to environment in ways not possible previously. Additional merits of these fourth-der ivative analyses for use in environmental studies are discussed.