Using biomimetics to understand marine invertebrate larval settlement and recruitment

Recruitment of benthic marine invertebrates is critical to population dynamics. Behavior of larvae (i.e., settlement preference) and physical transport processes may determine recruitment; however, they are not well understood. The goal of this project was to examine the relative roles of behavior and physical transport on settlement and recruitment of the barnacle Semibalanus balanoides. Larvae were photographed on natural rock at 10 sites in the intertidal. Larvae were also photographed on replicas of the 10 natural rock sites, fabricated using soft lithography, that were placed randomly at the same sites in the intertidal. There were two peaks in settlement on all natural sites: the first in early February, which had been observed before, and another in mid-March that had not been previously observed. This suggested that similar physical mechanisms were responsible for transporting larvae, but that they were different from previous years. Research is ongoing to determine the physical mechanisms that could cause these differences. Settlement was also greatest at two sites, on both the natural rock and replica panels. However, settlement was not significantly different on the replicas of these rocks placed at other sites. This suggests that settlement depended on macro-habitat  rather than settlement preference for micro-habitat (i.e., microtopography, or pits and grooves in the rock). However, it remains unclear why larvae exhibit preference for macro-habitat. These results are important for understanding the factors that influence settlement and recruitment, which impacts population dynamics, community structure, and population connectivity of benthic marine invertebrates.