EFFECTS OF SETTLEMENT DENSITY ON SPATIAL ARRANGEMENT IN 4 INTERTIDAL BARNACLES

Balanus amphitrite was studied in an estuary (Halifax River) in centra l Florida from October to November 1990, while three other barnacle sp ecies were studied on the central coast (Monterey Bay) of California f rom April 1988 to July 1989. Mean nearest-neighbor distances indicated that in the majority of cases the spatial arrangement of settlers was random for three different balanomorph barnacles-B. amphitrite, B. gl andula, and Chthamalus dalli. In Pollicipes polymerus, a lepidomorph s pecies, strong aggregation among settlers was almost always observed. In the three balanomorph species there was no apparent relationship be tween settler density and the degree of aggregation. In P. polymerus t here was a significant positive correlation between settler density an d the degree of aggregation. Morphological differences between balanom orph and lepidomorph barnacles may influence the evolution of settleme nt behavior.