RESOURCE USE BY 5 SYMPATRIC PARROTFISHES IN THE SAN-BLAS ARCHIPELAGO,PANAMA

Resource use by five sympatric species of parrotfish was quantified in the San Bias Archipelago of the Republic of Panama from March to Augu st 1987. Detailed observations of parrotfishes on patch reefs and surr ounding seagrass beds showed that they partition resources with respec t to habitat, food and size, but not time. Although parrotfishes share d resources, the proportions of each resource used differed significan tly among species. Scarus iserti (Bloch) scraped filamentous microalga e that grew from eroded coral pavement on lower slopes of patch reefs and in ''halos,'' the area of sparse vegetation surrounding reefs. Spa risoma viride (Bonnaterre) foraged on upper slopes of patch reefs wher e they mostly took bites from dead coral and associated algae. S. auro frenatum (Cuvier and Valenciennes) had the broadest diet, which consis ted mostly of seagrasses and macro- and microalgae that were attached to dead coral on lower reef slopes and in halos. Although S. chrysopte rum (Bloch and Schneider) commonly occurred on patch reefs, it primari ly foraged in seagrass beds that surround them. S. rubripinne (Cuvier and Valenciennes) was distributed most widely, ranging from seagrass b eds to reef crests, where it took bites from seagrasses, dead coral an d macroalgae. Juveniles of all species occurred on lower slopes or in halos where they scraped filamentous microalgae from coral pavement. A s they matured, parrotfishes moved into other habitats changing access to different types of food. All of these parrotfishes fed throughout the daytime, and resource use did not differ between morning and after noon.