Shallow water rhodoliths from Belize reefs

Composition, form (size and shape), and occurrence of shallow-water rhodoli ths (nodules of crustose coralline algae) from reefs of Belize, Central Ame rica, are detailed for the first time. The predominant rhodolith-builder is Hydrolithon boergesenii (FOSLIE). Most rhodoliths reach sizes between 32-4 8 mm (coarse gravel). The majority of rhodoliths are spheroidal, however, t heir shape is largely determined by the form of an interior coral core. Suc cessions of different species and changes in rhodolith growth forms are chi efly a consequence of changes in hydrodynamic properties during growth. A d ecisive factor for rhodolith development appears to be water agitation as a bundant rhodoliths occur only on exposed windward reef margins of Belize at oll reefs.