Laboratory investigations of the effects of predator sex and size on prey selection by the Asian crab, Hemigrapsus sanguineus

Selection of an omnivorous diet by the mangrove tree crab Aratus pisonii in laboratory experiments

“…Dimorphism in crab claw size has allowed males to feed on a wider variety of food items (Kyomo, 1992;Brousseau et al, 2001;Buck et al, 2003). Adult A. pisonii males tend to have larger club-shaped chelae (Warner, 1979), which may allow greater ability and force with which to grasp food items, and possibly greater breadth in diet as well.…”

Effect of predation by the invasive crab Hemigrapsus sanguineus on recruiting barnacles Semibalanus balanoides in western Long Island Sound, USA

“…Laboratory observations confirm that the Asian shore crab readily removes recruited barnacles from substrate surfaces (rocks, settling plates) and consumes them (McDermott 1998b, D. J. Brousseau unpubl.). Because of its small size (generally < 50 mm CW), however, it is capable of eating only juvenile shelled prey (Brousseau & Baglivo 2001), suggesting that the greatest predation impact in natural populations would occur early in the barnacle life cycle. In western Long Island Sound the recruitment period of Semibalanus balanoides overlaps with the onset of the seasonal activity cycle of H. sanguineus in mid-to late March.…”

“…It is particularly adept at scraping food from hard surfaces (McDermott 1998b), but it can crush or chip open small shelled prey. In the laboratory H. sanguineus has a demonstrable impact on juvenile shellfish prey (Brousseau & Baglivo 2001, Lohrer & Whitlatch 2002, Bourdeau & O'Connor 2003 and the green crab Carcinus maenas (Jensen et al 2002). Microcosm experiments run under laboratory and natural conditions also show that predation by H. sanguineus causes significant declines in juvenile mussels, barnacles, and ephemeral algae (Tyrrell et al 2006).…”

Simple and Complex Interactions

“…The Optimal Foraging Theory predicts that consumers will prefer prey that maximises the ratio of energy uptake relative to energy used for foraging, handling and feeding (Stephens and Krebs 1986) . Besides the identity, morphology or behaviour of the predator, prey characteristics like shell thickness (Brousseau et al 2001) , epibiosis (Laudien and Wahl 1999) , induction of byssus thread production (Cote 1995) or the presence of shell-boring species (Buschbaum et al 2006) can further complicate prey size selections by predators in opposing directions and with different magnitudes.…”