9321892 Connell The objectives of the present project are several: 1) To extend the detailed long-term monitoring of ecological communities of corals and algae on the Great Barrier Reef, Australia which has been carried on continuously over the past 30 years, the longest such study on any coral reef; 2) to expand the study to include sites on two nearby reefs, and additional replicate sites on Heron Reef; 3) to analyze spatial patterns and dynamics of corals and algae at several scales, from centimeters to tens of meters, both during the course of colonization of patches (opened by disturbances) and after most of the surface has become crowded by many colonies. These analyses should reveal the long-term effects of interactions that may be crucial in determining how natural communities are structured; 4) to test with controlled field experiments some hypotheses about mechanisms: a) that produce the unique species composition of corals at the Inner Reef Flat site, b) that cause contrasting patterns of algae after disturbances, and c) that determine precisely how each colony affects its neighbors; 5) to build mathematical models and computer simulations of the dynamics of these populations and communities of corals and algae: a) to investigate the influence of past and present conditions on future changes, b) to characterize temporal and spatial dynamics, and c) to test hypotheses about the consequences of these dynamics to the community. The models will be also used to asses the degree to which community structure and dynamics may or may not be influenced by details of spatial relationships. The field methods will use the standard sampling techniques used over the past 30 years, to assure continuity in the long-term data base. The experimental methods, using coral transplanting and cages to exclude larger herbivores, have also been used before in this study and are well- established. Larval choice experiments and new recruit t ransplants have been carried out successfully by the co- investigators elsewhere on the Great Barrier Reef. The significance of this proposed research to the advancement of knowledge is that: 1) it deepens the general knowledge of how natural communities of corals and algae (the dominant sessile organisms on tropical and sub-tropical reefs), are assembled and structured in the face of changes in their environment over extended periods of time; 2) it reveals some of the mechanisms that link the environment with these community changes, and how both vary over short and long time periods and between small and larger spatial scales; and 3) it helps to predict the effect of environmental changes, including those caused by human activity, on these natural communities.
