Red grouper increase the amount of complex habitat in the bay by cleaning out holes that have been filled in with sediment, bits of broken shells, and dead algae. The red grouper dig out holes so they can hide from predators, but in the process they create habitat that is colonized by a suite of other organisms including commercially important organisms like Caribbean spiny lobster, black grouper, and numerous species of snapper. So far, my research suggests that a higher diversity of organisms can be found associated with red grouper holes when compared to other types of habitat in the bay. Now I am attempting to answer the question of why: Why are there more diverse assemblages of fish and crustaceans found in grouper holes? Is it because the grouper is so good at creating habitat? Are there more complex interactions between the colonizing species at work here? Do we see the same pattern of diversity other places where red grouper live? I will attempt to answer these questions through a combination of direct observations by divers, and by experimentally manipulating the communities associated with grouper holes (by removing or adding species) to determine the mechanisms that control diversity in the bay.
The ultimate goal of my research is to explore a unique example of a marine ecosystem engineer to enhance our understanding of the mechanisms by which biodiversity is maintained in marine systems. In addition, our current understanding of the full ecological effects of fishing by humans is lacking. In this case, a popular fisheries species (the red grouper) plays an important ecological role in its ecosystem. As it digs holes, the grouper creates habitat for other organisms. Lobsters and snappers are both themselves important fisheries species and seem to gain from the habitat building activities of the red grouper. If all the red grouper are caught, what happens to the habitat? And how might this affect the populations of lobster and snapper? By studying the communities that develop in response to habitat manipulation by red grouper, I hope to quantify the interactions between the grouper and the other species. Understanding the interactions between organisms that are targeted by fisheries will ultimately help in the development of sustainable fishery practices and allow us to maintain biodiversity in the oceans.