Environmental Biology of Fishes

, Volume 10, Issue 3, pp 183–193

Diet, intestinal morphology, and nitrogen assimilation efficiency in the damselfish, Stegastes lividus, in Guam

  • Dennis R. Lassuy
Full paper

DOI: 10.1007/BF00001125

Cite this article as:
Lassuy, D.R. Environ Biol Fish (1984) 10: 183. doi:10.1007/BF00001125

Synopsis

Analysis of stomach contents of Stegastes lividus revealed a shift from omnivory in juveniles to herbivory in adults. Red algae, primarily Polysiphonia spp., Gelidiopsis intricata and Ceramium spp., formed the bulk of the diet in all size classes. Foraminifera and small crustaceans were of particular importance in the diet of juveniles. Net nitrogen assimilation efficiency of field-fed S. lividus was approximately 61%, and did not vary with fish size. The net assimilation efficiencies of fish fed on Enteromorpha in the laboratory ranged from size-class means of 36–79% for nitrogen and from 29–72% for total organic material, and increased from juveniles to adults. Apparently, juveniles compensate for a lower efficiency in assimilating plant food by including a higher percentage of animal material in their natural diets. The ratios of intestine length to standard length (IL/SL) and to intestine diameter (IL/ID) increased rapidly in juveniles and leveled off in adults. The retention time for ingested food items may only be about one-half as long in juveniles as in adults. The combination of observed IL/ID ratios and estimated retention times proved most valuable in the interpretation of ontogenetic changes in feeding habits and assimilation efficiency.

Keywords

PomacentridaeEupomacentrusHerbivorousFeeding habitsGut morphologyOntogenetic changes

Copyright information

© Dr W. Junk Publishers 1984

Authors and Affiliations

  • Dennis R. Lassuy
    • 1
  1. 1.Oregon Cooperative Fishery Research UnitOregon State UniversityCorvallisU.S.A.