Master’s Thesis Abstract

DETERMINING INTERSPECIFIC INTERACTIONS BETWEEN THE DOMINANT MACROPHYTES OF TROPICAL, ATLANTIC SEAGRASS MEADOWS.

by

Braxton C. Davis

Florida International University, 1998

Miami, Florida

Professor James W. Fourqurean, Major Professor

Though often suggested in seagrass literature, interactions between abundant rhizophytic macroalgae and coexisting tropical seagrasses have not been directly examined. Based on a competitive interaction hypothesis, I first tested for negative correlations between species densities over large and small spatial scales. After finding negative correlations, I tested experimentally for a competitive interaction by manipulating the relative densities of the locally dominant seagrass and a representative macroalga. Based on significant growth responses to density manipulations, I demonstrated that these species are likely competing for some limiting resource, possibly nitrogen. This study contributes to a better understanding of processes that dictate community composition in these systems.