Chemical sensing of microhabitat by pueruli of the reef-dwelling Caribbean spiny lobster Panulirus argus: testing the importance of red algae, juveniles, and their interactive effect

Although our knowledge about the early life of the Caribbean spiny lobster, Panulirus argus (Latreille, 1804), has increased considerably during recent decades, little is known about chemical sensing used by pueruli during settlement. Considering previously-reported benefits of inhabiting red algae Laurencia spp., such as increased growth rate and costs of close proximity to already settled benthic juveniles from predators, we predicted that the pueruli of P. argus will be attracted to the metabolites produced by red algae and repulsed by metabolites produced by juvenile conspecifics. We also expected that any preference for Laurencia spp. would cease or decrease if this cue was presented together with metabolites produced by conspecific given the reported costs of associating with them after settlement. Our results were not consistent with the predictions above. Our experiments suggest that pueruli do not display any preference for the metabolites produced by red algae or avoidance of metabolites produced by juvenile conspecifics. Unexpectedly, settling stages were attracted to water with a combination of metabolites produced by red algae and juveniles. We also examined the influence of conspecific and red algae abundance on pueruli settlement in Florida Bay, the most important nursery ground of P. argus in the USA. Partially consistent with our experiments, field data indicated that juvenile lobster density had a positive influence on pueruli settlement, as did a synergistic effect of juvenile lobster density and Laurencia spp. algae cover. Altogether, our field and laboratory data suggest that the interplay of environmental cues drives settlement of the Caribbean spiny lobster in a more complex manner than originally thought. Additional studies on the settling behavior of P. argus pueruli are needed to improve our understanding of the relationship between recruitment and fishery stocks in this heavily exploited species.