Comparing the behavior and morphology of wild-collected and hatchery-propagated long-spined urchins (Diadema antillarum): implications for coral reef ecosystem restoration

Coral reefs in the Caribbean Sea have progressively degraded in recent decades due to multiple stressors that include the mass mortality of a keystone invertebrate herbivore, Diadema antillarum (Philippi, 1845), in the 1980s. The population of D. antillarum in the Florida Keys has yet to recover, but recent advances in rearing captive-spawned D. antillarum have raised the possibility that D. antillarum can be produced in captivity and released into the wild as part of coral reef restoration efforts. However, organisms raised under artificial conditions could differ from their wild counterparts in ways that might reduce their fitness. Therefore, we conducted a series of experiments that compared the behavioral and morphological characteristics of hatchery-propagated and wild-collected D. antillarum. We demonstrate that hatchery-propagated D. antillarum raised in a non-rugose environment do not display the crevice shelter-seeking behavior of wild individuals. However, they did respond to the chemosensory stimulus of a potential predator, although they did not exhibit the escape behavior exhibited by wild individuals. Hatchery-propagated D. antillarum also exhibited lower spine density than wild individuals, likely the result of being maintained in conditions that did not induce spine breakage. However, this apparent habitat-induced morphological deficit was mitigated by maintaining them in rugose conditions. Our results suggest that competent hatchery-propagated D. antillarum can eventually be produced for coral reef restoration efforts, but they also underscore the need to further evaluate whether the behavioral deficiencies we identified can be effectively mitigated to ensure that ecologically competent individuals can be produced for such efforts.