Citation: Maggs, C.A. 1984 A seasonal study of seaweed communities on subtidal maerl (unattached coralline algae) in Galway Bay, Ireland. Progress in Underwater Science 9: 27-39
Number of Pages: 13
Keywords: Alga, Ecology, Flora, Galway, Maerl, Marine, Methods, Monitoring, Seaweed, Sublittoral
Abstract: Seasonal changes of algae on two subtidal maerl beds in Galway Bay were investigated during 1980 and 1981 by a combination of field and laboratory observations on field material, and laboratory culture under controlled conditions. The cover of macro-algae was measured underwater by use of a ruled clear perspex grid. Subsamples of maerl and attached algae from each grid area were collected intact and the percentage cover of small species obtained using a point quadrat method. The optimum subsample size (of 300 cm ) was ascertained from species-area curves. All macroalgal species were counted in each subsample. Seasonal changes were apparent on both maerl beds, but were more marked at 5 m, which dominated in summer by almost 100% cover of Dictyota dichotoma, while at 10 m the maximum cover was 60%. A few species, such as Atractophora hypnoides and Halymenia latifolia were represented in winter only by cryptic phases of their life histories. Environmental stimuli governing the seasonal behaviour of these species were investigated in laboratory culture.