Jaruwan Mayakun, Jeong Ha Kim, Brian E. Lapointe, and Anchana Prathep

pp. 211 - 216

Abstract

Halimeda macroloba Decaisne is a reef builder that provides habitats for many marine organisms and is important
for the production of calcium carbonate sediments. This species is one of the most common and abundant algae in tropical
regions of the Indo-Pacific Ocean. However, the trigger for reproduction of H. macroloba is not well understood. We have
examined 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). Nutrient
and salinity were found to have triggered reproduction. Gametangial clusters were produced along the outer margin of segments and the gametophores had a long stipe and were dichotomously branched at their distal end. Divided and sessile
gametangia were observed. This description of the variable gametangial morphology of H. macroloba is reported for the first
time.