Benthic Habitat Mapping in High Energy Nearshore Environments Using Acoustic
Methods. B. J. DEAN1 and E. A. IRLANDI2. 1 - School of the Earth Ocean and
Environment – Marine Science Program, University of South Carolina, 712 Main Street,
PSC 108, Columbia, SC 29208 (803)-777-4535, deanbj@email.sc.edu. 2 - Department of
Marine and Environmental Systems, Florida Institute of Technology, 150 W. University
Blvd., Melbourne, FL 32901 (deceased).
Hard bottom and sedimentary habitats in the nearshore are affected by anthropogenic
disturbances, such as beach nourishment. Current monitoring practices rely on visual
techniques, such as aerial and underwater photography, conducted on an annual basis and
do not allow rigorous assessment of the effects of man induced, or even natural events,
on the distribution and composition of these essential habitats. These practices are
extremely user biased and have significant associated errors. By incorporating
technology into the highly dynamic environment of the surf zone, we demonstrated that
unbiased, reliable, and consistent results were possible. We investigated the use of an
acoustic ground discrimination system (RoxAnn) to determine changes in benthic
habitats in the nearshore area of northern Indian River County, FL where hard bottom
outcrops occur. This area has also been subjected to numerous beach nourishment
projects. We determined the precision of the acoustic method and conducted multiple
surveys to assess temporal and spatial changes in bottom types. We mapped the spatial
distribution of several sediment types, bare rock surfaces, Sabellarid worm reef, sponge
covered rock, and rock covered with two different algal morphologies over large areas
under conditions of suboptimal visibility. Short term (monthly) changes in the
distribution of rock and sand habitats were detected over a relatively calm summer
season, suggesting that annual monitoring is insufficient to assess the impacts of episodic
disturbances such as beach nourishment on benthic habitats.
BIOGRAPHY
Bradley Dean received his undergraduate degree in marine science and biology from
Coastal Carolina University in 2007 and his master’s degree in environmental sciences
from Florida Institute of Technology in 2009. He is currently a PhD student at the
University of South Carolina in their Marine Science Program. Bradley’s primary
interests include: acoustic acquisition and sediment transport as well as its seasonality
and distribution. Unfortunately, Dr. Elizabeth Irlandi passed away October 20, 2010
from breast cancer and this was her last research project.