Gamete release is increased by calm conditions in the coenocytic green alga Bryopsis (Chlorophyta)

Water motion did not inhibit gamete release in cultures of the coenocytic g reen alga Bryopsis plumosa (Hudson) C. Agardh; however, the number of gamet angia that released gametes increased significantly under transiently calm conditions. This stimulatory effect of calm conditions in the laboratory wa s found in isolates from two different areas of the Maine coast. The isolat es were all monoecious, but strong differences in levels of fertilization, numbers of male and female gametes remaining following fertilization, and l evels of polygamy (= zygotes formed by fusions of more than two gametes) we re observed among isolates. These data support the hypothesis that organism s with external fertilization are able to sense and respond to water motion in ways that favor reproductive success.