Displaced juvenile and subadult Caribbean spiny lobsters show strong orientation toward home dens

Abstract

Caribbean spiny lobsters are known to undergo migration as adults, but the dispersal and homing ability of subadults and juveniles is not well characterized. Given that settlement habitat for juveniles is inshore seagrass / hardbottom and reproductive habitat is offshore coral reefs, dispersal during ontogeny serves as a bottleneck potentially limiting adult population density. Previous studies have examined factors associated with movement and den selection by juvenile lobsters such as shelter type, predators, and conspecific density. Their attraction to odors of healthy conspecifics plays a significant role in aggregation of lobsters in casitas and traps. But what is unknown is whether juvenile lobsters possess the map and compass orientation found in adults. To examine the ontogeny of homing ability, we conducted multiple mark / displace tracking studies using acoustic telemetry in juvenile hardbottom and subadult coral patch reef habitats. All lobsters regardless of size tend to relocate to new crevice shelters when handled, even if returned to their original shelter. Thus, for non-displaced lobsters tagged and returned to their point of capture, distance and angle travelled appears to be random with distance increasing as function of body size. However, for juvenile and subadult lobsters tagged and displaced away from their point of capture, the distance and angle travelled when released is significantly directed toward the point of capture. Thus, it appears that the map and compass ability of Caribbean spiny lobsters appears early in ontogeny and may allow for individuals to safely explore unfamiliar locations while retaining knowledge of how to return to known shelter. This ability to expand their known habitat map while maintaining knowledge of critical diurnal shelter locations is expected to facilitate their ontogenetic dispersal to adult habitat.