Publication Date:
2016-06-04
Description:
We investigated how fast the 15 N and 13 C stable isotope signature of copepods changes and how fast the isotope signals in microzooplankton and copepods change in the field. In experiments C1, copepodites of the copepod Acartia tonsa raised on Rhodomonas baltica were switched to a diet of Oxyrrhis marina and the 15 N and 13 C signature followed for 8 days. The 15 N increased by 0.18 ± 0.03 day –1 in animals fed O. marina while it decreased by 0.14 ± 0.02 day –1 with a R. baltica diet and equilibrium was reached after 5 days. Enrichment of nitrogen 15 N ( 15 N) was 2.4 ± 0.26 with R. baltica and 4.1 ± 0.38 with O. marina as food, and corresponding factors for carbon ( 13 C), 1.7 ± 0.38 and 2.3 ± 0.30. 15 N in the field, using seston 0–10 µm as the baseline, ranged from 2.4 to 3.1 for copepods and 1.0 to 1.6 for the microzooplankton (10–90 and 90–200 µm). Nitrate input resulted in low 15 N for copepods (2.4) and high for microzooplankton (1.4–1.6), indicating that copepods were feeding indiscriminately on phyto- and microzooplankton after the event. The second period showed higher 15 N (3.1) and a higher trophic level of copepods, but lower of microzooplankton (1.0–1.1).
Print ISSN:
0142-7873
Electronic ISSN:
1464-3774
Topics:
Biology
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