(full paper is archived in the Miller Library)
Title: Desiccation effects upon whole thallus absorbance and mitosis in the high intertidal alga Prophyra perforata (Rhodophyta)
Student Author(s): Rintoul, Evelyn B.
Faculty Advisor(s): Abbott, Isabella
%E Harding, Larry
Location: Final Papers Biology 175H
Date: June 1978
Keywords: biological rhythms in marine and maritime organisms
Abstract: A study of whole thallus absorbance was combined with direct measurements of photsynthesis in air to assess the photosynthetic capacity of desiccated Porphyra perforata. Fresh P. perforata was found to give a flat absorbance spectrum of high absorbance. Drying of the sample produces pigment peaks in the spectrum and a reduction in the photsynthetic rate. On rehydration, P. perforata resumes full photosynthetic capacity, and again exhibits a flat spectrum at high absorbance. The suggestion is made that these spectral results reflect an adaptation to P. perforata's intertidal habitat, for the subtidal Porphyra nereocystis gave peaks for both desiccated and fresh samples. In addition, photosynthetic rates measured during the day were higher than those measure at night, introducing the possibility that P. perforata possesses an endogenous photosynthetic rhythm. Cytological examination of P. perforata collected in situ over a 24 h period showed greatest mitotic activity when the plants were exposed during daylight hours.