The influence of bottom type and stratification on reef fish community structure at GRNMS

Physical and oceanographic differences across reef habitats can influence fish distribution. In this study, Gray\u27s Reef National Marine Sanctuary (GRNMS) was surveyed both inside and outside an MPA using echosounder technology and a CTD profiler to assess physical and environmental controls driving reef fish communities. Preliminary results from a PCA-analysis suggest that differences in fish community structure are driven by physical characteristics (e.g. presence of relief and biofouling cover) and water column stratification. The influence of stratification on reef fish structure seems to be present even with changes in the physical structure. However, the physical structure still seems to be playing the primary role in fish distribution along the reef. Understanding the roles that bottom type and water column stratification play in fish community structure can help to prioritize the preservation of bottom habitats and promote healthier, more complex ecosystems