Experiments on some effects of certain environmental factors on Gracilaria verrucosa (Hudson) Papenfuss

Abstract

At an early stage of an autecological study of Gracilaria verrucosa (Hudson) Papenfuss it seemed possible that the best growth of the plants occurred in places, such as the Achill Sound and the Church Island Channel in the Menai Straits, where, in the absence of heavy wave action, strong currents flowed over the plants. Experiments were carried out, in the sea, to investigate the effect of currents on the growth rate; the apparatus used and described here would probably be suitable for the investigation of current effects on other sedentary marine organisms.These experiments also led to some observations on the effects of illumination on the pigmentation and growth rate of the plants which were supplemented by laboratory experiments. High intensity illumination in the laboratory also demonstrated positive phototropism in the plant.