Predation on Bivalve Veligers by Polychaete Larvae

Abstract

Polychaete larvae from several families are thought to be natural predators upon planktonic bivalve larvae. However, little direct evidence of interactions between these predators and prey is available. We conducted predator-prey experiments on laboratory roller tables for five putative predatory polychaete larvae, representing four families (metatroch-less larvae of the Polynoidae and metatrochophore larvae of the Spionidae, the Magelonidae, and the Phyllodocidae). D-hinge veliger larvae of the oyster Crassostrea gigas were offered as prey. Predation was monitored over a range of prey densities and in the presence and absence of background plankton. "Background plankton" are any naturally occurring plankton assemblages found in whole, unfiltered seawater at ambient concentrations. For all polychaete larvae examined, when natural C. gigas densities and background plankton were used, no predation was observed. Magelonids and phyllodocids did not consume any C. gigas larvae, regardless of conditions. Polynoid and spionid trochophores consumed C. gigas veligers at both the "natural" and unnaturally high prey densities in filtered seawater. The addition of background plankton eliminated the predation at all natural prey densities and significantly reduced the predation observed at high prey densities.

Low rates of predation on planktonic marine invertebrate larvae

“…However, after 2 or more days, the abundance and composition of background plankton, especially protists, can begin to change dramatically in a relatively small closed system. Background plankton is known to have a profound effect on predation rates (Johnson & Brink 1998) and this was behind our choice to limit observations to 24 h. At the close of experiments, corrals were hauled from the sea and corral water exited through the codend bucket. Contents were fixed immediately in 4% buffered formalin.…”

“…The gut contents of selected predators (all cnidarians, all ctenophores, chaetognaths, fishes, and Arctonöe vittata trochophores) were examined to determine predation on wild larvae. These predators were selected because they are considered by many to be important predators and their typical prey sizes encompass the sizes of larvae in corrals (Nelson 1925, Hirota 1974, Bailey et al 1975, Hobson & Chess 1976, Reeve 1980, Purcell & Mills 1988, Rumrill 1990, Purcell et al 1991, AlvarezCadena 1993, Chandy & Greene 1995, Morgan 1995, Phillips & Pernet 1996, Johnson & Brink 1998. The most common prey items observed were adult copepods, nauplii (Table 5), and phytoplankton.…”

Morphology, feeding and behaviour of British Magelona (Annelida: Magelonidae), with discussions on the form and function of abdominal lateral pouches

“…Bivalve and polychaete larvae, pelagic eggs and tintinnids have been recorded in the diets of magelonid larvae (Lebour, 1922;Thorson, 1946;Smidt, 1951;Kühl, 1974;Wilson, 1982). Although doubts exist as to whether natural predation on bivalve larvae is common (Johnson and Brink, 1998), prevalence may be higher in laterstage larvae (Wilson, 1982;Johnson and Brink, 1998). McIntosh (1911) and Mare (1942) additionally reported the presence of sand, silt and debris, which likely concurs with our observations for M. mirabilis, and lends support for the presence of interspecific variation in feeding between co-existing magelonid species.…”

Stage-specific distribution of barnacle larvae in nearshore waters: potential for limited dispersal and high mortality rates

“…Lamare & Barker 1999), in open coastal waters it requires observations of plankton distribution at spatial and temporal scales that are seldom achieved (but see Natunewicz et al 2001). Thus, laboratory (Johnson & Brink 1998) and indirect field methods are usually employed to estimate mortality from ratios of local larval production to recruitment (e.g. Connell 1970), or from information on the stage composition of larvae over a given area (Aksnes et al 1997).…”