Abstract

The fishing down of marine food webs has been described in pelagic and demersal systems but rarely documented in coral reef environments. We recorded a rapid shift in fish community structure in Belize that accompanied a marked decline in grouper and snapper abundance and a switch towards smaller (less desirable), herbivorous parrotfishes. In a 6-7 year period (2002-2008/9), observations of large-bodied grouper (Serranidae) declined significantly from an encounter probability of 21% per 200 m2 transect to just 2%. The biomass of carnivorous snappers (Lutjanidae) underwent a 7-fold decline, primarily in the species Ocyurus chrysurus. Parrotfish biomass declined by 41% between 2002 and 2008/9. A tri-trophic cascade occurred in which mesopredators (e.g.,Cephalopholis fulvus)increasedby 880% of 2002 levels and caused a crash in damselfish populations by ~45%. We discuss the implications for reef resilience.