Table 5.

Student-Newman-Keuls' (SNK) Test Comparison of Chlorophyll a concentrations for Control, Nitrogen (N), Phosphorus (P), and Nitrogen plus Phosphorus (N + P), and phosphorus gradient treatments (P1–P5, representing progressively higher P concentrations) using Passive Diffusion Periphytometer in the Bosque River Watershed during the period of July 30 – August 13, 1998.

Site	Treatment	Number of Replicates	Mean Chl. a (μg cm-2)	Standard Deviation (μg cm-2)	SNK Group (α = 0.05)
NB-03	C	8	0.49	0.24			C
	N	9	0.86	0.35			C
	N+P	9	4.55	1.92	A
	P1	7	0.67	0.17			C
	P2	7	0.71	0.24			C
	P3	9	0.67	0.24			C
	P4	9	0.85	0.42			C
	P5	9	0.79	0.19			C
NB-05	C	9	0.99	0.26			C
	N	9	1.02	0.42			C
	N+P	8	2.15	0.50		B
	P1	9	1.08	0.34			C
	P2	9	1.13	0.37			C
	P3	9	1.17	0.36			C
	P4	8	0.89	0.34			C
	P5	9	1.99	0.59		B