The effects of changes in temperature and salinity on the behavior of the hermit crab Pagurus longicarpus

Hermit crabs of the species Pagurus longicarpus can be found in many Massachusetts tide pools. Temperatures and salinities in tide pools change far more rapidly than they do subtidally; moreover, climate change is predicted to bring warmer temperatures and increased rainfall to Massachusetts. Hermit crabs have no hard abdominal carapace and must rely on empty gastropod shells for shelter. In this research, I determined the size of shells that hermit crabs preferred in seawater of different temperatures and salinities and studied how changes in temperature and salinity affected their ability to find shelter and food. Hermit crabs in seawater of high temperature (33 °C) and salinity (40 ppt) were unlikely to occupy high quality shells within 24 h, and hermit crabs in low salinity seawater (20 ppt) often did not locate food within 15 min, suggesting that hermit crabs will struggle to find adequate shelter and food in the future.