Abstract
Existing viewpoints and theories of selective grazing by copepods are briefly reviewed in order to formulate explicit hypotheses to be tested experimentally. Based on these hypotheses, a series of grazing experiments was run to determine (1) the extent of the selective ingestion capabilities of Acartia clausi and (2) how these capabilities were affected by previous feeding histories. Groups of copepods were separately preconditioned on a small diatom (Thalassiosira pseudonana), a large diatom (T. fluviatilis), or a plastic sphere. The ingestive behavior was then examined on various combinations of spheres and food particles. Spheres offered alone were not ingested. In mixtures of diatoms and spheres, the copepods avoided ingesting spheres intermediate in size between the sizes of the diatoms. The copepods either ingested particles on either side of the spheres, or ignored all particles less than the size of the largest spheres. The pattern observed depended upon the size of the preconditioning food. However, if the spheres were larger than the largest food particles, the copepods still selectively ingested the food particles. The above results demonstrate that A. clausi has a complex grazing behavior consisting of (1) more efficient grazing on larger particles within its particle-size ingestion range; (2) the ability to alter “effective” setal spacing to optimize feeding behavior (i.e., the ability to increase efficiency of capture of food particles, and to avoid non-food particles); and (3) the ability for post-capture rejection of non-food particles when they interfere with the ingestion of food particles on which the copepod has been preconditioned. The behavioral patterns observed depend heavily on the food preconditioning and the presence or absence of non-food particles. These results clearly indicate that a simple “mechanistic” explanation of selective grazing is insufficient.
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Literature Cited
Boyd, C.M.: Selection of particle sizes by filter-feeding copepods: a plea for reason. Limnol. Oceanogr. 21, 175–180 (1976)
Conover, R.J.: Oceanography of Long Island Sound, 1952–1954. VI. Biology of Acartia clausi and A. tonsa. Bull. Bingham Oceanogr. Coll. 15, 156–233 (1956)
— Feeding on large particles by Calanus hyperboreus (Krøyer). In: Some contemporary studies in marine science, pp 187–194. Ed. by H. Barnes. London: George Allen & Unwin Ltd. 1966
— Some relations between zooplankton and bunker C oil in Chedabucto Bay following the wreck of the tanker Arrow. J. Fish. Res. Bd Can. 28, 1327–1330 (1971)
Conover, R.J. Feeding interactions in the pelagic zone. J. Cons. int. Explor. Mer (in press)
Donaghay, P.L. and L.F. Small: Long-term food modification by Acartia clausi: a preliminary view. Mar. Biol. 52, 129–136 (1979)
Friedman, M.M. and J.R. Strickler: Chemoreceptors and feeding in calanoid copepods (Arthropoda: Crustacea). Proc. natn. Acad. Sci. U.S.A. 72, 4185–4188 (1975)
Frost, B.: Effects of size and concentration of food particles on the feeding behaviour of the marine planktonic copepod Calanus pacificus. Limnol. Oceanogr. 17, 805–815 (1972)
— Feeding behaviour of Calanus pacificus in mixtures of food particles. Limnol. Oceanogr. 22, 472–491 (1977)
Gamble, J.C., J.M. Davies and J.H. Steele: Loch Ewe bag experiment, 1974. Bull. mar. Sci. 27, 146–175 (1977)
Harvey, W.H.: Note on selective feeding by Calanus. J. mar. biol. Ass. U.K. 22, 97–100 (1937)
Lam, R.K. and B.W. Frost: Model of copepod filtering response to changes in size and concentration of food. Limnol. Oceanogr. 21, 490–500 (1976)
Lehman, J.T.: The filter-feeder as an optimal forager, and the predicted shapes of feeding curves. Limnol. Oceanogr. 21, 501–516 (1976)
Marshall, S.M. and A.P. Orr: The biology of a marine copepod, 188 pp. London: Oliver & Boyd 1955
Mayzaud, P. and R.J. Conover: Influence of potential food supply on the digestive enzyme activity of neritic copepods. Proc. 10th Eur. mar. Biol. Symp. 2, 415–427 (1976). (Ed. by G. Persoone and E. Jaspers. Wetteren, Belgium: Universa Press)
— and S.A. Poulet: The importance of the time factor in the response of zooplankton to varying concentrations of naturally occurring particulate matter. Limnol. Oceanogr. 23, 1144–1154 (1978)
Mullin, M.M.: Some factors affecting the feeding of marine copepods of the genus Calanus. Limnol. Oceanogr. 8, 239–250 (1963)
Nival, P. et S. Nival: Efficacite de filtration des copepods planctoniques. Annls Inst. océanogr., Paris (N.S.) 49, 135–144 (1973)
—— Particle retention efficiencies of an herbivorous copepod, Acartia clausi (adult and copepodite stages): effects on grazing. Limnol. Oceanogr. 21, 24–38 (1976)
O'Connors, H.B., L.F. Small and P.L. Donaghay: Particle-size modification by two size classes of the estuarine copepod Acartia clausi. Limnol. Oceanogr. 21, 300–308 (1976)
Poulet, S.A.: Grazing of Pseudocalanus minutus on naturally occurring particulate matter. Limnol. Oceanogr. 18, 564–573 (1973)
— Seasonal grazing of Pseudocalanus minutus on particles. Mar. Biol. 25, 109–123 (1974)
Richman, S., D.R. Heinle and R. Huff: Grazing by adult estuarine calanoid copepods of the Chesapeake Bay. Mar. Biol. 42, 69–84 (1977)
Schnack, S.: Untersuchungen zur Nahrungsbiologie der Copepoden (Crustacea) in der Kieler Bucht, 144 pp. Dissertation, Universität Kiel 1975
Storm, S.: Selective feeding, ingestion and assimilation rates and distribution of the copepod Acartia in Chesapeake Bay, 162 pp. Baltimore. Ph.D. Thesis, John Hopkins University 1974
Strickler, J.R. and G. Rosenberg Visual observation of filter-feeding by copepods. A. Mtg Am. Soc. Limnol. Oceanogr. Abstr. (June 1977), p. 56 (1977). (East Lansing, Michigan: Michigan State University)
Wilson, D.S.: Food size selection among copepods. Ecology 54, 909–914 (1973)
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Communicated by J.M. Pérès, Marseille
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Donaghay, P.L., Small, L.F. Food selection capabilities of the estuarine copepod Acartia clausi . Marine Biology 52, 137–146 (1979). https://doi.org/10.1007/BF00390421
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DOI: https://doi.org/10.1007/BF00390421