Distribution of Sipuncula in the Coral Reef Community, Carrie Bow Cay, Belize

A survey of sipunculan fauna associated with coral rocli and rubble along a transect across the coral reef at Carrie Bow Cay, Belize, revealed eight species, six of which inhabited burrows within rock samples and two of which occurred in crevices and crannies. Comprising 95 percent of the collection, the four most abundant species were, in order of abundance: Lithacrosiphon alticonus Ten Broeke; Aspidosiphon brocki Augener; Phascolosoma perlucens Baird; and Paraspidosiphon sleenslrupi (Diesing). The greatest concentration of sipunculans, measured as number per square meter of surface area of rock, occurred in reef-crest material. Sipunculans were least abundant in material from the patch-reef zone of the back reef and from the fore-reef slope. The four most abundant species showed a distinct distributional pattern along the transect. Generally, sipunculans from the same reef habitat were densest in fresh, relatively unaltered coral rock having little secondary infill of calcitc cement and a rather uniform skeletal framework characteristic of species of Ponies and Acropora. Samples of more highly eroded, commonly well-cemented, and presumably older rocks contained few, if any sipunculans. Aspects of sipunculan distribution suggested for further study include reproductive strategy and variations in substrate characteristics.