ISSN:
1432-1793
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Vertical distribution, chlorophylla (chla) and phaeopigment concentrations in the gut, and natural nitrogen isotope ratio (δ 15N) were investigated for pelagic amphipodsThemisto japonica (Bovallius) collected from the Sea of Japan in July 1987. Differences in diel vertical migration behavior were clearly observed between small and largeT. japonica. Many small (〈5 mm body length) amphipods appeared in the phytoplankton-rich shallow layers. Their gut pigment concentrations were higher (mean 0.52 ± 0.15µg chla g−1 amphipod) than those of large amphipods (mean 0.33±0.14µg g−1); this implies that the amphipods fed on a large amount of phytoplankton during the early stage of life. Theδ 15N values of small amphipods were lower (5.7 to 6.3‰) than those of large amphipods (6.8 to 11.7‰), reflecting the lower trophic level of small amphipods compared to large ones. Theδ 15N values for small amphipods were similar to those of herbivorous zooplankton. The amphipods' feeding behavior thus changes from herbivorous to carnivorous as they grow.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01319392
