Appendix A. Equations used to estimate N and P excretion rates of gizzard shad.
Excretion rates were directly quantified in the lakes in the months indicated, as described in the source references. Pexc = P excretion rate (µg P excreted·fish-1·h-1), Nexc = N excretion rate (µg N excreted·fish-1·h-1), M = fish body mass (g wet mass).
Lake and date |
P excretion rate |
N excretion rate |
Source |
Burr Oak, July 1999 |
log Pexc = 1.626 + 0.673log M |
log Nexc = 2.393 + 0.647logM |
1 |
Burr Oak, June 2000 |
log Pexc = 1.573 + 0.675log M |
log Nexc = 2.470 + 0.714logM |
1 |
Burr Oak, July 2001 |
log Pexc = 1.505 + 0.715log M |
log Nexc = 2.617 + 0.379logM |
1 |
Pleasant Hill, July 1999 |
log Pexc = 1.502 + 0.687log M |
log Nexc = 2.430 + 0.561logM |
1 |
Pleasant Hill, June 2000 |
log Pexc = 0.902 + 0.971log M |
log Nexc = 2.647 + 0.521logM |
1 |
Pleasant Hill, July 2001 |
log Pexc = 1.317 + 0.747log M |
log Nexc = 2.206 + 0.452logM |
1 |
Acton, June 1994 |
log Pexc = 1.358 + 0.816log M |
log Nexc = 1.914 + 0.887logM |
2 |
Acton, August 1994 |
log Pexc = 0.988 + 0.877log M |
log Nexc = 1.991 + 0.845logM |
2 |
Acton, July 1999 |
log Pexc = 1.732 + 0.499log M |
log Nexc = 2.173 + 0.675logM |
1 |
Acton, June 2000 |
log Pexc = 1.384 + 0.689log M |
log Nexc = 2.480 + 0.640logM |
1 |
Acton July 2001 |
log Pexc = 1.164 + 0.905log M |
log Nexc = 1.738 + 0.738logM |
1 |
1 Higgins, K. A., M. J. Vanni, and M. J. González. In press. Detritivory and the stoichiometry of nutrient cycling by a dominant fish species in lakes of varying productivity. Oikos.
2 Schaus, M. H., M. J. Vanni, T. E. Wissing, M. T. Bremigan, J. E. Garvey, and R. A. Stein. 1997. Nitrogen and phosphorus excretion by detritivorous gizzard shad in a reservoir ecosystem. Limnology and Oceanography 42:1386–1397.