Meeting Abstract
Marine invertebrates frequently exhibit complex life cycles, including major life history transitions that coincide with habitat changes. In many marine invertebrates, adults live on the bottom of the ocean (the benthos), and broadcast spawn their gametes into the water column, where fertilization occurs and they begin life drifting in the water column as planktonic embryos and larvae, eventually metamorphosing into juveniles and returning to the benthos at settlement. Morphological phenotypic plasticity in response to environmental cues, may be especially important for organisms with complex life histories. As echinoderm larvae approach settlement, waterborne cues from the benthos may provide information about the future juvenile habitat, permitting expression of phenotypes that may improve post-metamorphic survival and performance. Larvae are known to detect and respond to the composition of the benthos when selecting settlement sites, but little is known about how benthic predator cues received by larvae affect juvenile phenotypes. We tested whether cues from a predator in a future habitat (the benthos) can be perceived by echinoderm larvae in their current habitat (the plankton) and modify juvenile phenotypes as they settle to the benthos. Larvae of Dendraster excentricus and Strongylocentrotus droebachiensis were exposed to predatory crab cues once juvenile rudiment formation began. S. droebachiensis exposed to crab cues as larvae had significantly more juvenile spines at settlement than those not exposed to the cue; however, there was no significant difference in spine length, disk area, or age at settlement. In contrast, D. excentricus larvae exhibited earlier settlement when introduced to a crab cue. These results suggest that planktonic larvae are capable of responding to benthic cues, but those responses may vary among species.
