Associations Between Winter Temperatures and the Timing and Duration of Annual Larval Recruitment of a Non-native Anomuran Crab

Abstract

The green porcelain crab, Petrolisthes armatus, a subtropical/tropical species, was first recorded on intertidal oyster reefs in South Carolina in 1995. Since then, its range has expanded north in a series of surges and setbacks that appear to be associated with particularly cold winters that may cause mortality. Petrolisthes armatus reproduces year-round in its native range whereas its reproductive season in the non-native range is limited to warmer months. Variation in the timing and duration of larval recruitment is not known for the non-native range and these factors may affect further range expansion. To determine whether P. armatus larval recruitment is related to temperature variation, in particular, the severity of winter temperatures, archival biweekly (every 2 weeks) larval samples collected 1994–2018 near its northern range limit in the North Inlet Winyah Bay National Estuarine Research Reserve (NERR) were examined. The goal was to determine whether the timing and duration of larval ingress varied over time and was related to temperature variation. Petrolisthes armatus larvae were first observed in samples collected in 1995. There was considerable interannual variability in the timing of the start of recruitment (coefficient of variation 29%), which ranged from the last week of March at the earliest to the last week of July at the latest, for all years but one. Earlier annual recruitment was positively correlated with a longer recruitment duration. The timing of first larval recruitment was also related to the severity of the preceding winter, with later larval recruitment occurring in years with several consecutive days of cold temperatures. Cold winter temperatures appear to affect overwintering populations and their ability to reproduce in the early spring. A decreasing frequency of severe winters along the coastal South Atlantic Bight may promote further poleward range expansion of P. armatus.