| Abstrakt: |
AbstractSeasonal food availability for benthic feeders in Antarctica can influence the level of excreted metabolites, which may then be a source of N and P for autotrophs. In this study, we examined the effects of starvation of Waldeckia obesaand Glyptonotus antarcticuson the excretion of both N and P, and the chemical composition of their bodies. N-NH4+dominated in the pool of excreted nitrogen (93% and 77% of inorganic nitrogen, and 76% and 67% of total nitrogen, for W. obesaand G. antarcticus, respectively). Reactive phosphorus dominated in the pool of excreted phosphorus (72% and 65% of total phosphorus for G. antarcticusand W. obesa, respectively). The excretion of N-NH4+(in µmol N h−1100 g−1) dropped from 3,687 (W. obesa)and 1,336 (G. antarcticus)in the first day to about 0.6 after 10 days of starvation (for both species). Phosphorus excretion was generally lower than that of nitrogen (on average 0.046 and 0.017 µmol P h−1100 g−1for G. antarcticusand W. obesa, respectively), but no clear trend appeared with N as a result of starvation. The greatest decrease in nitrogen and protein content in W. obesawas recorded on the 3rd day of starvation (nitrogen: from 1.30% to 0.93%; protein: 8.15% to 5.80%) and in G. antarcticuson the 5th day of starvation (nitrogen: from 2.22% to 1.43%; protein: from 13.86% to 8.94%). Conclusions: (i) nitrogen and phosphorus compounds released by crustaceans may be a supplementary source of biogenic salts for autotrophs, (ii) nitrates constituting approx. 20% nitrogen may be used by phytoplankton in the period of new production, (iii) starvation reduces the excretion of N and P and the content of nitrogen and protein in crustaceans. |
