THE VARYING FUNCTIONAL ROLE OF CTENOCHAETUS STRIATUS: AN ANALYSIS OF BEHAVIOR & MORPHOLOGY IN TOP-DOWN VERSUS BOTTOM-UP REEF ENVIRONMENTS IN PALAU

Abstract

The Ctenochaetus striatus (common name: Striated Surgeonfish) is an herbivorous reef fish found on most Pacific reefs. They are considered to be detritivores in the guild of herbivorous fish as they are best adapted to sweeping their food off the reefs’ epithelial algae matrix (EAM) with their bristle-like teeth. Much is known about their role in sediment removal on the reef. During feeding they ingest sediments coating the reef algae and carry and excrete the sediment off the reef making the algae more palatable to other herbivores that feed on and remove the large algal turfs. This cleaning function is extremely important to maximizing reef resilience and coral larva settlement. Beyond understanding this general relationship not much else is known about the life of the striated surgeonfish even though they are a dominant population on many reefs. As such they are believed to be a vital component of the energy and nutrient flows between primary reef producers and primary reef consumers. C. striatus may play an important role in most, if not all “reef ecosystems,” but each system is different and it may not be valid to generalize the life cycle and function of even the same species in different environments. Various complex dynamics and interactions impact the arrangements of a reef ecosystem. Coral reefs are one of the world’s most productive ecosystems harboring vast numbers of species resulting in extreme biodiversity. Not surprisingly the significance of even small variation between these ecosystems is not well understood. This lack of understanding can only be remedied by the further study of species ideally in a presently stable and controlled reef environment currently best approximated by marine protected areas. In order have and create effective marine protected areas the target goal of the area and the life cycle and functional niches of species vital to this goal must be well understood. This study identifies multiple behavioral and morphologic adaptations of C. striatus in nearby, but different reef environments and survival stresses. Specific characteristics and functional roles of C. striatus populations existing on a top-down predator dominated environment are compared with fish living in a bottom-up resource limited one. It is hoped the study’s findings of these varied roles will have implications for the future planning of marine protected areas by providing a more detailed analysis of varying reef environments and the varying roles a single species may play in them.