Gametangial characteristics in the sexual reproduction of Halimeda macroloba Decaisne (Chlorophyta: Halimedaceae)

Abstract

Halimeda macroloba Decaisne is a reef builder that provides habitats for many marine organisms and is importantfor the production of calcium carbonate sediments. This species is one of the most common and abundant algae in tropicalregions of the Indo-Pacific Ocean. However, the trigger for reproduction of H. macroloba is not well understood. We haveexamined some environmental factors that might trigger reproduction and determined the gametangial characteristics of H.macroloba. The peak seasonal reproduction of H. macroloba occurred within only a 3-month period (May-July). Nutrientand salinity were found to have triggered reproduction. Gametangial clusters were produced along the outer margin of segmentsand the gametophores had a long stipe and were dichotomously branched at their distal end. Divided and sessilegametangia were observed. This description of the variable gametangial morphology of H. macroloba is reported for the firsttime.

Keywords

• gametangial clusters
• nutrient
• reproduction
• salinity