Stress tolerance of photosynthesis in sporelings of the red alga Grateloupia doryphora compared to that of Stage III thalli

Abstract

More experimental evidence is needed to understand the role of propagules in macroalgal biology. There are no reports in the literature on the comparative physiology (e.g. photosynthesis) of sporelings and adults. In this paper we report on the␣variation␣in␣photosynthetic parameters (maximum photosynthesis, P _max , and efficiency, alpha, and dark respiration (R _d ) of cultivated young sporelings of the red alga␣Grateloupia␣doryphora (Montagne) Howe under normal conditions and after a short-term incubation at different salinities and temperatures. The results are compared to those␣for␣adult Stage III thalli obtained in laboratory culture from the same population of sporelings. The pigment composition of sporelings (more chlorophyll a and less phycoerthryn and phycocyanin than adults) promotes a better photosynthetic performance (higher P _max and alpha and lower R _d ) under chlorophyll a excitation. The younger sporelings were also more tolerant to variations in salinity and temperature than Stage III, in which the highest variation in maximum photosynthesis and dark respiration was observed.