Parasites of Crustaceans and Fishes in the Indian River Lagoon, Florida: A Meta-Analysis Across Intertidal Systems and Taxa

Parasites are often used as indicators of ecosystem health. Habitats with high biodiversity are also rich in parasites, especially trophically transmitted parasites that rely on predation between hosts to complete life cycles. In this study, we surveyed parasite prevalence to assess the trophic complexity of seagrass-associated food webs in the Indian River Lagoon (IRL), a 252-km estuary on Florida’s Atlantic coast that has experienced extensive seagrass die-offs. We quantified infection prevalence in intertidal species of crustaceans and fishes in the IRL and used meta-analysis of studies in comparable systems to provide context for our results. Overall, parasite prevalence in the IRL was roughly 11% lower than that documented in other coastal and estuarine systems. Of note, the prevalence of larval-stage trophically transmitted parasites requiring two or more hosts to complete life cycles was approximately 17% lower in the IRL, suggesting that food web complexity is reduced or unstable in our system. The IRL watershed is predominantly suburban; however, the parasite data suggest that trophic complexity is more comparable to studies conducted in urban environments. Due to ongoing issues with water quality, seagrass coverage in the IRL is often ephemeral and fragmented, which likely restricts the movement of hosts and contributes to lower parasite prevalence in remnant habitat patches. Restoration efforts are ongoing, and our parasite data can be used as a baseline for assessing the return of trophic complexity to the IRL following decades of nutrient pollution and seagrass loss.