Life-histories of Bryopsis plumosa (Chlorophyceae, Caulerpales) from European coasts

Zygotes of Bryopsis plumosa from Naples, Banyuls, and Biarritz grew into filamentous germlings which divided into stephanokontic zoids. Some of the germlings from Naples and Banyuls developed directly into new Bryopsis plants. In culture these germlings have a longer “dormancy” period than those of Bryopsis plumosa collected in more northern regions (Zeeland, Roscoff). Bryopsis plumosa from Naples could interbreed with Roscoff material to produce germlings that only developed through stephanokontic zoids. Bryopsis plumosa from Naples could also interbreed with Zeeland material and produced germlings that only developed directly into new Bryopsis plants (which is characteristic for Bryopsis plumosa from Zeeland). Zinc-chlor-iodide and Congo red positively stain the walls of the Bryopsis phase, and negatively the walls of the germling phase. On the basis of these results the lifehistories and the site where meiosis takes place in the life-history of Bryopsis plumosa are discussed.