The zonation patterns of Caribbean coral reefs as controlled by wave and light energy input, bathymetric setting and reef morphology: computer simulation experiments

Abstract

The computer model COREEF was used to simulate variations in the zonation patterns of Caribbean reefs in relation to parameters that affect the magnitude and distribution of wave and light energy. We first developed a simulated standard reef by exposing a simplified profile of the reef at Discovery Bay, Jamaica, to the known wave and light energy conditions to establish a reference coralgal and sedimentological zonation pattern. We then varied 13 parameters related to the wave and light energy input, bathymetric setting, and gross morphology of this reef to determine the effects of each parameter on the zonation pattern. Analysis of the simulation results indicates that submerging the reef or altering the wave or light energy input to the reef produces the greatest modifications of the zonation pattern. Morphological structures that alter a reef's horizontal dimensions only minimally affect the zonation pattern, but those structures that alter a reef's vertical dimensions-particularly steep-sided, wave reflecting structures-can significantly modify the zonation of the structure itself and that of more leeward areas. The more seaward the location of a morphological structure, the more profoundly it can affect the overall reef zonation. If waves break at the reef crest, wave energy conditions in the back reef are greatly reduced and the bottom consists of lower wave energy zones than those found at the same depths in the fore reef. If waves do not break at the crest, the back reef is subjected to almost the same wave conditions that exist in the fore reef, and the zones tend to be similar. The zonation patterns of some existing reefs resemble those of our simulated reefs, but other zonation patterns cannot be reproduced accurately because our simulation experiments do not consider the interactions between multiple parameters found on many existing reefs.