Quantifying hermit crab recruitment rates and megalopal shell selection on wave-swept shores

Abstract

The availability of shells has been shown to limit populations of adult hermit crabs and alter the outcome of interspecific interactions. However, few studies have addressed such issues in newly settled crabs. A major impediment has been the absence of techniques to quantify the use of shells by settling crabs. Here we present a simple technique for assessing hermit crab recruitment in rocky habitats. The method appears to measure differences in settlement rates among sites without substantial bias. By offering several different species of microgastropod shells, we also found that settling Pagurus hirsutiusculus have distinct shell preferences. Such shell preferences may lead to resource limitation at the juvenile stage which may have cascading effects on the distribution, abundance, or shell use patterns of adult hermit crabs.