GSA Annual Meeting in Indianapolis, Indiana, USA - 2018

Paper No. 96-41
Presentation Time: 9:00 AM-6:30 PM


CARLSON, Claire, Department of Earth and Environmental Sciences, University of Iowa, Iowa City, IA 52240, MILBRANDT, Eric, Marine Laboratory, Sanibel-Captiva Conservation Foundation, Sanibel, FL 33957 and CRAMER, Bradley D., Department of Earth and Environmental Sciences, University of Iowa, 115 Trowbridge Hall, Iowa City, IA 52242

In many coastal areas, excess nutrients from terrestrial sources have led to rapid growth in hypoxia, algae blooms and loss or degradation of habitat. Macroalgae is well-known for ecosystem services including nutrient sequestration and can be used to restore eutrophic waterways, while simultaneously creating economic opportunities through aquaculture practices.

To determine the viability of macroalgae aquaculture in Sanibel, Florida, three testing sites along with two different techniques (enclosed vs. exposed) were established. All three testing sites were equipped with two macroalgae aquaculture lines. One line featured exposed macroalgae attached by fishing line and the other held macroalgae samples enclosed in mesh bags. The goal of this project was to see which method would lead to the greatest amount of algal growth, as well as which techniques were the most influential for aquaculture success in Tarpon Bay.

The project spanned a total of four weeks during the months of July and August. Each line had three different macrolagae species: Gracilaria Bursa-Pastoria, Gracilaria Tikvahiae, and Ancanthophora spicifera that were alternated on the line. A YSI sonde was used to gather data, such as temperature, dissolved oxygen, pH, salinity, and turbidity, as a way to monitor the daily conditions at the three sites. Plaster of Paris Clod Cards were also attached to the aquaculture lines to illustrate flow rates at the sites. Lastly, a laboratory tissue strength test was performed on all three species of algae to determine the algaeā€™s ability to fracture.

After performing the various tests, the species Gracilaria bursa-pastoris proved to be the most durable, while also having the highest growth rate as measured with volume displacement. This species appears to be the best macroalgae of those tested for aquaculture practices in Tarpon Bay. From the results, areas that are shallow with increased flow rates provide the best growing conditions.