Ecological Archives E092-034-A4

Gaston E. Small, Catherine M. Pringle, Mark Pyron, and John H. Duff. 2011. Role of the fish Astyanax aeneus (Characidae) as a keystone nutrient recycler in low-nutrient neotropical streams. Ecology 92:386–397.

Appendix D (TABLE D1). Best statistical models (based on lowest corrected Akaike information criterion value) for N and P excretion rates, and N:P excretion ratio, when points at minimum detection limit are included (n = 531). R2 values for N, P, and N:P excretion models are 0.22, 0.27, and 0.10, respectively.

Log N excretion rate
Parameter Estimate (SE) DF t value P βstd
Intercept 0.821 0.104 1 7.89 < 0.001  
Log wet body mass (g) 1.152 0.095 1 12.08 < 0.001 0.426
Insects in diet (%) 0.374 0.123 1 3.03 0.003 0.118
Log P excretion rate
Intercept 0.453 0.257 1 1.76 0.078  
Log wet body mass (g) 0.958 0.090 1 10.63 < 0.001 0.543
Body P (%) -0.175 0.054 1 -3.27 0.001 -0.188
Insects in diet (%) 0.350 0.115 1 3.05 0.002 0.170
Stream SRP 0.005 0.001 1 5.00 < .001 0.289
Log N:P excretion ratio
Intercept 2.640 0.315 1 8.37 < 0.001  
Body N:P ratio 0.347 0.076 1 4.58 < 0.001 0.035
Insects in diet (%) -1.823 0.421 1 -4.33 < 0.001 -0.873
Stream SRP -0.003 0.001 1 -4.13 < 0.001 -0.171

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