Reproductive ecology of Gracilaria pacifica Abbott (Gracilariales; Rhodophyta), in Estero de Punta Banda, Mexico

Abstract

Two populations of Gracilaria pacifica Abbott, that grow on different types of substrates (mud-sand and rochy) and that differ in the type and dominance of reproductive phases, were studied in Estero de Punta Banda, Baja California (Mexico). To determine whether the lack of hard (rocky) substrate, which allows attachment, and the viability of the tetraspores are related to the absence of cystocarpic plants in beds distributed on a soft substrate (mud-sand), the attachment and viability of the tetraspores, on an artificial substrate (concrete slabs), were evaluated in situ and under semicontrolled culture conditions. The fertility and viability of the tetraspores under controlled laboratory conditions were quantified. The tetraspores from both stations germinated under controlled and semicontrolled conditions. Germination in situ occurred only at the station with hard substrate. In the mud-sand environment, growth of plants on the artificial substrates placed among the beds was not observed. It is concluded that the absence of cycstocarpic plants in G. pacifica beds that grow on a mud-sand substrate cannot be attributed to the lack of hard (rocky) substrate or the viability of the tetraspores.