Holocene sea-level rise has been the most significant natural influence on the evolution of both physical and biological aspects of east Central Florida's continental margin. Under conditions of rising Holocene sea level the barrier island system has retreated landward through erosional shoreface retreat. This landward retreat of the barrier island system has led to constantly changing conditions of water quality, substrate composition, circulation, and water depth within the Indian River Lagoon. These changes have taken place over a broad range of spatial and temporal scales. Because each of these parameters influence coastal biodiversity, it can be assumed that at least some of the historical changes noted to have occurred within the Indian River Lagoon are a natural response to Holocene sea-level rise and the concomitant landward retreat of the barrier island system. -from Author