Coral Reefs: Present Problems and Future Concerns Resulting from Anthropogenic Disturbance

Coral reefs, with their vast diversity of invertebrate, vertebrate and algal species, have undoubtedly been subjected to natural disturbance since their appearance millions of years ago. Anthropogenic disturbance has been a factor affecting reefs for a fraction of that time, yet in terms of overall impact, may be of greater concern. Data on habitat destruction, pesticide and heavy metal accumulation, nutrient loading, sedimentation, runoff and related impacts of man's activities indicate that many coastal reefs are endangered by these processes through alterations in animal-algal symbioses, shifts in competitive interactions, direct mortality, reproductive failure, and insufficient recruitment. The death of corals critically affects reef communities, as corals provide an important trophic link as well as the main habitat structure. While natural disturbance is an important factor affecting reef interactions, species diversity and evolution, chronic anthropogenic disturbances combined with unsuitable environments for recovery, are of great concern. Physiological stress can be measured in corals in addition to outright mortality, allowing the impacts of specific disturbances to be assessed. Sufficientdata for distinguishing real problems from temporal variability are becoming available, allowing scientists to focus on practical solutions to problems in coral reef management and preservation.