MANGROVE SPECIES DISTRIBUTION AND PROPAGULE PREDATION IN BELIZE - AN EXCEPTION TO THE DOMINANCE PREDATION HYPOTHESIS

Predation on mangrove propagules was studied to assess its impact on t he intertidal distribution of Rhizophora mangle, Avicennia germinans, and Laguncularia racemosa. Field experiments conducted on a mangrove i sland range (Twin Gays) in Belize showed that rates of predation (perc ent of propagules rendered nonviable in 9 days) just after peak disper sal (December) were highest for A, germinans (60 +/- 8%) and significa ntly lower for R, mangle (18 +/- 5%) and L. racemosa (28 +/- 9%), whic h were not significantly different. Rates varied seasonally, however, with highest losses of propagules at the beginning of dispersal (July) . Major predators were the mangrove crabs, Goniopsis cruentata and Uci des cordatus The high predation rate on A, germinans propagules was at tributed to a relatively small size (facilitating burial in crab burro ws), a higher nutritive content, and lower amounts of defensive chemic als such as tannins. Interspecific differences in predation rates, how ever, could not explain the relative dominance and spacial distributio n of two of the three species that comprise this intertidal community. Comparison of predation rates in forest locations dominated by either R. mangle or A. germinans demonstrated that consumption of R, mangle propagules was highest in areas where it dominated the canopy and lowe st where A, germinans was dominant. Predation also could nor account f or the infrequent occurrence of L, racemosa trees at Twin Gays, since rates of propagule consumption were not different from that of R. mang le and significantly less than that of A. germinans. High densities of L. racemosa seedlings further suggested that predators were not preve nting this species' establishment here. Only the predation pattern for A. germinans was consistent with intertidal dominance of trees. The r esults indicate that differential predation plays a less important rol e in the zonation of these island mangrove forests than has been repor ted for other geographic regions.