THE EFFECTS OF CHEMICAL CUES ON CARIBBEAN KING CRAB LARVAE (MAGUIMITHRAX SPINOSISSIMUS) METAMORPHOSIS AND SETTLEMENT 

In the Florida Keys, coral habitats have declined since the 1970s due to various stressors including coral bleaching, diseases, and marine heat waves. This decline has resulted in a shift from coral-dominated communities to macroalgal-dominated habitats, resulting in ecosystems with lower economic and ecological value. To address the increase in macroalgae,  restoration efforts propose outplanting herbivorous grazers such as the Caribbean king crab (Maguimithrax spinosissimus) onto Florida reefs. In this study, we determined which chemical cues influence settlement in king crab larvae using five different chemical cue treatments representing potential positive and negative settlement cues. These included: control (purified ozonated seawater), chemically defended algae (Dictyota spp.), conspecifics (M. spinosissimus), and spiny lobster (Panulirus guttatus, predator). Larvae were monitored at six-hour intervals until the juvenile stage, during which we documented individual survival and time to metamorphosis across treatments. Our results indicate the presence of Dictyota spp. and P. guttas in habitats will likely result in significantly lower larval settlement rates with on average smaller juveniles, whereas normal conditions and conspecific cues will likely result in significantly higher larval settlement rates with on average larger juveniles. These findings suggest that restoration and aquaculture efforts could enhance survival and settlement rates for king crab larvae by incorporating conspecific cues during their development. By understanding the environmental cues promoting or deterring settlement, this research provides valuable insights for coral restoration organizations in the Florida Keys, offering a strategic approach to mitigate the impacts of macroalgal shifts and contribute to the health of coral ecosystems.

For more information, email: taqueen@eckerd.edu