Reproductive characteristics and behavior of the green porcelain crab (<i>Petrolisthes armatus</i>) in its introduced range
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Wassick, Ann
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Abstract
Invasive species are one of the many threats faced by marine habitats today and there are many characteristics that successful invaders share, including high reproductive output potential and small size at sexual maturity. One invasive species, the green porcelain crab (<i>Petrolisthes armatus</i>) is common in its introduced range, however its reproductive characteristics including mating behaviors are not known or have not been directly assessed. Crabs were collected from five locations in the introduced range (Wilmington, NC; Georgetown, SC; Charleston, SC; Bluffton, SC; and Savannah, GA) at two sites at each location, with small sample sizes at the Wilmington sites precluding their inclusion in analyses. At each site, ovigerous female abundances, reproductive output, and egg number and egg quality measurements were calculated. At two sites, Town Creek and Pinckney Landing, allometric relationships, based on eight body measurements, were assessed to determine size at sexual maturity. I compared fecundity estimates and size at sexual maturity among populations along a latitudinal gradient and reproductive output and smallest ovigerous female to estimates in the native range. At Grice only, I hand collected crabs to conduct a laboratory experiment to examine the effects of sex ratio (all-male, all-female and mixed-sex) on crab spacing measured by nearest-neighbor (NN) distances and inferred potential mate acquisition behaviors. Crabs held in aerated tanks under a constant density and three sex ratio treatments and were observed twice daily for position and interactions for five day durations. Mean NN distances calculated for focal crabs in each tank were compared between mixed-sex and single-sex treatments. Crabs at the northern locations, which are at the range limit of <i>P. armatus</i> within the introduced range, appear to be maximizing reproductive potential and NN results are consistent with male <i>P. armatus</i> protecting access to prospective mates. Results of this study have helped fill knowledge gaps for this species in its introduced range.