Benthic Habitat Preference by Callinectes sapidus in Indian River Lagoon, Florida
Presentation Type
Short presentation 10-15 minutes
In Person or Zoom Presentation
In-Person
Campus
Daytona Beach
Status
Student
Student Year and Major
Masters, Integrated Environmental Science
Invited Speaker Institution/Department
Bethune-Cookman University
Presentation Description/Abstract
Historically, seagrass beds (e.g., Halodule wrightii, Thalassia testudinum) have provided critical nursery grounds for juvenile blue crabs, offering shelter and abundant foraging opportunities. However, recurring system-wide algal blooms have led to declines in seagrass cover and an increase in macroalgae relative abundance, such as Gracilaria tikvahiae. Macroalgae have been known to offer structural refuge for juvenile blue crabs elsewhere, but its suitability as a long-term nursery habitat in the IRL remains uncertain. To investigate this issue, long-term datasets dating from 1998-2023 from the Florida Fish and Wildlife Conservation Commission (Fisheries-Independent Monitoring) and the St. Johns River Water Management District (Seagrass and Macroalgae Surveys) have been analyzed. Spatial and statistical modeling, including Generalized Additive Models, has linked blue crab presence and abundance to habitat parameters (seagrass percent cover, water quality, etc.) across multiple sampling years. Additionally, ex situ experiments using a controlled raceway design were conducted to compare habitat preference between macroalgae- and seagrass-dominated settings. Juvenile blue crabs were observed for selection patterns and subjected to gut content analyses to highlight any dietary differences tied to specific benthic structures. Results indicate that blue crab demographics were strongly correlated with seagrass abundance prior to the 2012 die-off but exhibited weaker associations thereafter, reflecting a reduced reliance on seagrass as habitat. Ex situ trials showed no significant preference between seagrass and macroalgae, suggesting that both habitats can serve as short-term refuge for juveniles. Results will inform fisheries management, highlighting the importance of balancing macroalgal proliferation with ecological integrity in the IRL’s changing ecosystem.
Keywords
Indian River Lagoon, blue crab, seagrass die-off, macroalgae, nursery habitat, estuarine ecology
Benthic Habitat Preference by Callinectes sapidus in Indian River Lagoon, Florida
Historically, seagrass beds (e.g., Halodule wrightii, Thalassia testudinum) have provided critical nursery grounds for juvenile blue crabs, offering shelter and abundant foraging opportunities. However, recurring system-wide algal blooms have led to declines in seagrass cover and an increase in macroalgae relative abundance, such as Gracilaria tikvahiae. Macroalgae have been known to offer structural refuge for juvenile blue crabs elsewhere, but its suitability as a long-term nursery habitat in the IRL remains uncertain. To investigate this issue, long-term datasets dating from 1998-2023 from the Florida Fish and Wildlife Conservation Commission (Fisheries-Independent Monitoring) and the St. Johns River Water Management District (Seagrass and Macroalgae Surveys) have been analyzed. Spatial and statistical modeling, including Generalized Additive Models, has linked blue crab presence and abundance to habitat parameters (seagrass percent cover, water quality, etc.) across multiple sampling years. Additionally, ex situ experiments using a controlled raceway design were conducted to compare habitat preference between macroalgae- and seagrass-dominated settings. Juvenile blue crabs were observed for selection patterns and subjected to gut content analyses to highlight any dietary differences tied to specific benthic structures. Results indicate that blue crab demographics were strongly correlated with seagrass abundance prior to the 2012 die-off but exhibited weaker associations thereafter, reflecting a reduced reliance on seagrass as habitat. Ex situ trials showed no significant preference between seagrass and macroalgae, suggesting that both habitats can serve as short-term refuge for juveniles. Results will inform fisheries management, highlighting the importance of balancing macroalgal proliferation with ecological integrity in the IRL’s changing ecosystem.