Effect of dietary history on selection of prey, and foraging behaviour among patches of prey, by the dogwhelk, Nucella lapillus (L.)
Hughes, R.N.; Dunkin, S. de B. (1984). Effect of dietary history on selection of prey, and foraging behaviour among patches of prey, by the dogwhelk, Nucella lapillus (L.). J. Exp. Mar. Biol. Ecol. 79(2): 159-172. http://dx.doi.org/10.1016/0022-0981(84)90217-X In: Journal of Experimental Marine Biology and Ecology. Elsevier: New York. ISSN 0022-0981; e-ISSN 1879-1697, more |  |
| Authors | | Top | - Hughes, R.N., more
- Dunkin, S. de B.
| | |
| Abstract | Dogwhelks originating from a population without access to mussels but maintained on a mixed diet of barnacles and mussels subsequently showed a preference for barnacles, whilst those maintained for 60 days on mussels developed a strong preference for mussels. Those that had never experienced mussels largely ignored them when presented, but overwhelmingly preferred barnacles to which they were accustomed. Those maintained for 90 days on mussels and then for 60 days on barnacles regained a preference for barnacles but still consumed more mussels than dogwhelks maintained solely on barnacles. Effects of ingestive conditioning therefore persisted at least for 60 days during which they were modified by experience with the alternative prey. Preferences resulting from ingestive conditioning were never reversed by the relative profitabilities of barnacles and mussels or by their relative abundances in feeding trials. Nevertheless, except for those totally inexperienced with mussels, dogwhelks incorporated more of the currently less preferred species into their diet when it was relatively more abundant. They had an additional tendency to continue choosing the same species during a foraging bout, whether or not they had become ingestively conditioned to it, a tendency which would enhance the likelihood of ingestive conditioning in the field. The susceptibility of dogwhelks to develop a strong, but reversible, preference for mussels or barnacles through ingestive conditioning is conducive to switching which, if occurring naturally, would take at least several months to complete and the initially preferred prey would become depleted to low levels.Dogwhelks apparently perceived clumps of mussels, placed on Petri dishes 0.5 m apart, as discrete patches of prey. They foraged mainly in darkness, tending to rest in corners of the aquarium or at the edge of the water during the light. On encountering a patch, dogwhelks would crawl over it for ˜0.7 h if subsequently rejected and 6.0 h if accepted, contacting most of the component mussels. Patches were not chosen according to their initial profitability or to their initial biomass, but those already being exploited by dogwhelks were visited more frequently and rejected less frequently than unexploited ones. Dogwhelks stayed longer in the more profitable patches and depleted them more than the others because the larger mussels, comprising the more profitable patches, individually took longer to handle and accounted for a greater proportion of the total biomass. The aggregative feeding response and the preference for certain sizes of prey probably cause dogwhelks in the field to congregate and feed longer where the preferred prey are most plentiful. More profitable patches are expected to be exploited sooner than less profitable patches, as predicted by the Marginal Value Theorem, but contrary to the Theorem the chosen patches will probably continue to be exploited even when depleted to well below the average profitability of patches in the area. |
|
