Spatial scales of variability in temperate reef communities across a gradient of upwelling intensity

Environmental heterogeneity can have important effects on the structure of natural communities. For example, in marine ecosystems, variation in climate and oceanographic conditions results in large fluctuations in upwelling intensity and can influence primary production and recruitment of fish and invertebrates. This patchiness in environmental conditions can lead to variation in community similarity at particular scales. Knowledge of scales of variability in community structure and dynamics may help improve the ability of managers to track variability in ecosystems. To determine geographic patterns in community similarity and scales at which biological variation emerges, we conducted surveys of species composition and relative abundance for benthic invertebrates and algae across the Vizcaino peninsula, Baja California Sur, Mexico. This region is marked by geographical variation in upwelling intensity resulting in nearshore areas with exposure to different temperature regimes and levels of productivity. Results indicate that community similarity declines with geographic distance, suggesting that regional-scale oceanographic processes influence community structure. However, abundances of macroalgae and invertebrates were highly variable between sites within the region of persistent upwelling indicating that local scale processes also largely influence community structure and dynamics.