The Red Algal Epiphytes Microcladia coulteri Harv. and M. californica Farl. (Rhodophyceae, Ceramiaceae). III. The Effect of Light on Growth, Reproduction and Morphology

Abstract

Germlings of the epiphytic red algae Microcladia coulteri and M. californica were cultured at three different light intensities in order to observe the effect of irradiance on germination, growth, development of reproductive structures and overall thallus morphology. A light intensity of 25 μE m −2 s −1 was optimal for germination, germling growth and reproduction of both epiphytes. An intensity of 15 μE m −2 s −1 was as effective as 25 μE m −2 s −1 for M. californica but not for M. coulteri, in which the growth rate was significantly slower. At the highest light (50 μE m −2 s −1 ), germlings of both species generally grew as fast as at 25 μE m −2 s −1 but their thalli were covered with short adventitious branches