Life history of Chaetomorpha valida (Cladophoraceae, Chlorophyta) in culture

Abstract The marine green alga Chaetomorpha valida (Cladophoraceae, Cladophorales) has been found for several years fouling aquaculture ponds along coasts of the cities Dalian and Rongcheng, P.R. China. Using unialgal culture and microscopic observation, we completed the life history of C. valida and discovered fragment regeneration for the first time. The life history comprised an isomorphic alternation between gametophytes and sporophytes typical of most other members of the Cladophorales. Male and female gametes fused into zygotes then developed into sporophytes. Quadriflagellate zoospores produced by mature sprophytes gave rise to new gametophytes that yielded biflagellate gametes. Germination of zygotes and zoospores was of the bipolar erect type, as observed in some other species of Chaetomorpha. Fragment regeneration occurred in both gametophytes and sporophytes via production of polar algal fragments, which directly developed into entire filaments to give a self-replicating gene­ration. The result...