MEPS 186:219-225 (1999)  -  doi:10.3354/meps186219

The significance of feeding history on the value of heterotrophic microzooplankton as prey for larval crabs

Stephen D. Sulkin*, Gene L. McKeen

Shannon Point Marine Center, 1900 Shannon Point Road, Anacortes, Washington 98221, USA

ABSTRACT: Larvae of 4 species of crabs of the genus Cancer (C. gracilis, C. magister, C. oregonensis and C. productus) were raised in the laboratory from hatching to the post-larval megalopa stage on diets of nauplii of the brine shrimp Artemia sp. and on 2 diets of the rotifer Brachionus plicatilis. One of the rotifer diets had been cultured on the chlorophyte Dunaliella tertiolecta, the other on the chrysophyte Isochrisis galbana. In 3 of the 4 crab species, Dunaliella-fed rotifers did not support development to the megalopa, whereas Isochrisis-fed rotifers did. In the fourth species, C. productus, survival to the megalopa was only 1% on Dunaliella-fed rotifers, whereas Isochrisis-fed rotifers supported development equal to that of the Artemia-fed control. Differences between the 2 rotifer diets were evident in all species by Stage 3, although the first significant occurrence of increased mortality on the Dunaliella-fed rotifer diet varied among species. In all 4 species, development rate was faster as early as the first molt on the Isochrisis-fed rotifer diet as compared to the Dunaliella-fed rotifer diet, a difference maintained throughout development. Only in C. gracilis did survival to the megalopa on the Isochrisis-fed rotifer fall substantially below that seen for Artemia-fed larvae. Stage mortality on the Isochrisis-fed rotifer diet typically equaled that of the Artemia sp. control. Differences in development rates between the Isochrisis-fed rotifer diet and the Artemia sp. diet varied among species, as did megalopa weight. We attribute differences between the 2 rotifer diets to the high content of long-chain ω-3 polyunsaturated fatty acids in I. galbana and their absence in D. tertiolecta. The value of heterotrophic microzooplankton as prey for crab larvae, either in culture or in nature, will depend upon the prey's own feeding history.


KEY WORDS: Crab larvae · Diet · Heterotrophs · Microzooplankton


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