The ecological effects of hard-bottom habitat degradation on the Florida stone crab

Abstract

Repeated cyanobacterial blooms in Florida Bay have resulted in the degradation of hard-bottom habitat throughout the region. Despite the loss of structure-forming sponges, nothing is known about the effects on the iconic Florida stone crab, Menippe mercenaria, which utilize hard-bottom to shelter and forage. We examined the potential impacts of these algal blooms by comparing crab nutritional condition, trophic position, and site fidelity between bloom-impacted and non-impacted regions. Menippe mercenaria from both regions were of similar nutritional condition; however, δ¹⁵N stable isotope analysis revealed M. mercenaria to have greater trophic variability in bloom-impacted regions, suggesting crabs in degraded habitats foraged on a wider variety of prey. δ¹³C measurements showed a marked shift between regions, suggesting the source of primary production in these regions differed in δ¹³C values, species composition, or both. Site and den fidelity remained similar; likely due to the abundance of solution holes available as shelters. Overall, results indicate M. mercenaria have high resiliency to the habitat degradation caused by these blooms, but fundamental changes in their trophic ecology suggest that blooms could be causing a broader alteration to these communities.