Seagrass restoration efforts globally have been motivated by decreases in coverage associated with urban development and climate change. In the Indian River Lagoon (IRL), FL, seagrass beds declined by 58% between 2011-2019. During this time, the abundance of the native macroalga Caulerpa prolifera increased substantially in the IRL. It is not known how dense, continuous beds of C. prolifera could impact seagrass restoration projects in the IRL or natural recovery of this biogenic habitat. We tested the effect of C. prolifera density on planting the seagrass Halodule wrightii using mesocosms and a field experiment. Within mesocosms, growth of H. wrightii decreased with increasing C. prolifera density, providing evidence for density-dependent competition between these species. In the field, no effect was found of C. prolifera density on H. wrightii growth, but densities were much lower than in mesocosms. Overall, competitive effects of C. prolifera on H. wrightii are only detectable when C. prolifera is present in high densities. Practitioners of seagrass restoration should consider C. prolifera abundance as a factor which could impact projects but may not be as consequential as other more persistent drivers of environmental change.
Luciana Banquero
Dr. Linda Walters, Advisor
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