The Effect of Light on the Growth and Morphology of the Threatened Seagrass Halophila johnsonii

• Activity Number: 591
• Type: Contributed
• Date/Time: Wednesday, August 4, 2010 : 2:00 PM to 3:50 PM
• Sponsor: Section on Statistics and the Environment
• Author(s): Dexter C. Whittinghill*+ and Courtney E. Richmond and Kamille K. Hammerstrom
• Companies: Rowan University and Rowan University and Moss Landing Marine Laboratories
• Keywords: Multiple regression ; seagrass growth ; ambient light ; threatened species

Abstract

The threatened seagrass H. johnsonii has a limited habitat of 200 km of eastern Florida coastline. Seagrasses play a vital role in the subtidal marine community, providing habitat and food, and stabilizing the sediment. We simulated the effects of light-diminishing overwater structures (such as docks) on ambient light to study the effect on the growth and morphology of H. johnsonii. The predictors were year (1 and 2) and the proportion of ambient light to reach the plant (100%, 60% and 30%), while the five responses were the number of nodes, average internode distance, total biomass, average length of leaves, and proportion of total biomass on the primary branch. Multiple regression techniques were used to conclude that as light decreased, the number of nodes, internode distance, and total biomass decreased, while leaf length and proportion of biomass on the primary axis increased.