Table B1. Two-way ANOVA applied to the change in nutrient levels () from ~1 day before to 1 day after the nutrient pulse (see also Fig. 2 in the main text).
Response
Variable |
1999
|
2000
|
|||||
Source |
df |
F |
P |
df |
F |
P |
|
total N |
Zoop |
3, 15 |
0.15 |
0.93 |
3, 24 |
0.85 |
0.48 |
Pulse |
1, 15 |
29.01 |
<0.0001 |
1, 24 |
33.77 |
<0.0001 |
|
Zoop × Pulse |
3, 15 |
0.29 |
0.83 |
3, 24 |
1.00 |
0.41 |
|
total P |
Zoop |
3, 16 |
1.14 |
0.36 |
3, 24 |
0.31 |
0.82 |
Pulse |
1, 16 |
0.21 |
0.65 |
1, 24 |
38.56 |
<0.0001 |
|
Zoop × Pulse |
3, 16 |
0.93 |
0.45 |
3, 24 |
1.46 |
0.25 |
Notes: One mesocosm was not included in the 1999 TN analysis due to a lost sample. Effects for which P < 0.05 are indicated in bold font.
Table B2. Two-way analyses of zooplankton biomass variables sampled just prior to the nutrient pulse.
A) Two-way MANOVA on Daphnia, small cladoceran, and copepod biomass for 1999 and 2000. Rotifers were sufficiently rare that they were not included in this analysis. | ||||||
1999
|
2000
|
|||||
Source |
df |
F |
P |
df |
F |
P |
Zoopl. |
9, 48 |
10.33 |
<0.0001 |
9, 72 |
5.69 |
<0.0001 |
Pulse |
3, 14 |
0.06 |
0.98 |
3, 22 |
0.51 |
0.68 |
Zoopl. × Pulse |
9, 48 |
0.71 |
0.70 |
9, 72 |
0.33 |
0.96 |
B) Univariate, two-way ANOVA for each component of the MANOVA, plus total biomass including rotifers. There were 3 numerator df for the Zoop and Zoop × Pulse tests and 1 numerator df for the Pulse test, with 16 denominator df in 1999 and 24 in 2000. RV = response variable. | ||||||
1999
|
2000
|
|||||
RV |
Source |
F |
P |
F |
P |
|
Daphnia
|
Zoop
|
72.30
|
<0.0001
|
92.20
|
<.0001
|
|
|
Pulse
|
0.21
|
0.65
|
0.26
|
0.62
|
|
|
Zoop
× Pulse
|
0.07
|
0.97
|
0.02
|
0.99
|
|
Small cladocerans
|
Zoop
|
3.30
|
0.05
|
33.56
|
<.0001
|
|
Copepods
|
Zoop
|
12.63
|
0.0002
|
3.60
|
0.03
|
|
|
Pulse
|
0.04
|
0.85
|
0.88
|
0.36
|
|
|
Zoop
× Pulse
|
1.77
|
0.19
|
0.73
|
0.55
|
|
Total biomass
|
Zoop
|
14.94
|
<.0001
|
82.60
|
<.0001
|
|
|
Pulse
|
0.27
|
0.61
|
0.47
|
0.50
|
|
|
Zoop
× Pulse
|
1.34
|
0.30
|
0.25
|
0.86
|
|
C) Linear contrasts for the univariate ANOVAs in (B). There were two contrasts planned at the outset of the experiment: (1) No Added Zooplankton vs. the three +Zooplankton treatments, and (2) Copepod vs. Daphnia treatments. Degrees of freedom for the F test were (1,16) in 1999 and (1,24) in 2000. | ||||||
1999
|
2000
|
|||||
RV |
No Added
vs. +Zooplankton
|
Copepod
vs. Daphnia
|
No added
vs. +Zooplankton
|
Copepod
vs. Daphnia
|
||
Daphnia |
F = 38.15 P < 0.0001 |
F = 159.41 P < 0.0001 |
F = 276.30 P < 0.0001 |
F = 0.72 P = 0.41 |
||
Small cladocerans |
F = 2.61 P = 0.13 |
F = 2.09 P = 0.17 |
F = 100.32 P < 0.0001 |
F = 0.047 P = 0.83 |
||
Copepods |
F = 28.65 P < 0.0001 |
F = 5.87 P = 0.028 |
F = 3.15 P = 0.089 |
F = 0.025 P = 0.88 |
||
Total zooplankton |
F = 44.60 P < 0.0001 |
F = 0.23 P = 0.64 |
F = 243.84 P < 0.0001 |
F = 2.82 P = 0.11 |
Notes: These analyses evaluate the effects of the zooplankton treatments and check that there was no difference between control and pulse mesocosms prior to the pulse. Response variables were log10(x + 0.01) transformed prior to analysis; 0.01 was the minimum biomass observed in any zooplankton functional group. Results were qualitatively similar for density variables, but are not presented here.
Table B3. Backwards indicator variable regressions predicting sensitivity and return time from a zooplankton variable, a year indicator, and their interaction.
A) Sensitivity (Before/After metric) | ||||||||
Predictor | Intercept (95% CI) |
Slope (95% CI) |
Change in Int. (95% CI) |
Change in slope (95% CI) |
R2 | MSE | F | P |
Total biomass | 20.66 (17.23, 24.09) |
-12.39 (-15.48, -9.31) |
16.67 (9.72, 23.62) | 0.75 | 26.7 | 37.94 | 0.0001 | |
Cladoceran length | 17.60 (12.61, 22.59) |
-3.84 (-10.07, 2.39) |
16.35 (6.64, 26.07) | -26.82 (-38.47, -15.18) |
0.67 | 35.8 | 16.07 | 0.0001 |
Daphnia biomass | 9.73 (5.20, 14.25) |
-4.74 (-6.42, -3.07) |
7.64 (0.57, 14.70) | 0.61 | 42.3 | 19.28 | 0.0001 | |
Small cladoceran biomass | 11.37 (8.15, 14.59) |
-3.98 (-5.94, -2.02) |
0.40 | 64.4 | 17.44 | 0.0003 | ||
Copepod biomass | 17.65 (12.24, 23.06) |
-7.91 (-13.99, -1.84) |
0.22 | 84.4 | 7.17 | 0.0127 | ||
B) Sensitivity (Control/Pulse metric) | ||||||||
Predictor | Intercept (95% CI) |
Slope (95% CI) |
Change in Int. (95% CI) |
Change in Slope (95% CI) |
R2 | MSE | F | P |
Total biomass | 18.02 (14.81, 21.23) |
-10.15 (-13.03, -7.27) |
13.47 (6.97, 19.97) |
0.70 | 23.3 | 29.38 | 0.0001 | |
Cladoceran length | 16.17 (11.87, 20.46) |
-4.39 (-9.75, 0.96) |
12.89 (4.54, 21.24) |
-21.16 (-31.17, -11.15) |
0.66 | 26.4 | 15.62 | 0.0001 |
Daphnia | 8.99 (5.02, 12.97) |
-3.94 (-5.41, -2.47) |
6.22 (0.00, 12.43) |
0.58 | 32.7 | 17.31 | 0.0001 | |
Small cladocerans | 10.28 (7.51, 13.05) |
-3.33 (-5.02, -1.64) |
0.39 | 47.8 | 16.49 | 0.0004 | ||
Copepods | 15.46 (10.80, 20.11) |
-6.50 (-11.72, -1.27) |
0.20 | 62.4 | 6.54 | 0.0167 | ||
C) Return time (Before/After metric) | ||||||||
Predictor | Intercept (95% CI) |
Slope (95% CI) |
Change in Int. (95% CI) |
Change in Slope (95% CI) |
R2 | MSE | F | P |
Total biomass | 23.73 (18.71, 28.75) |
-11.36 (-15.88, -6.85) |
12.96 (2.78, 23.14) |
0.57 | 57.2 | 16.48 | 0.0001 | |
Cladoceran length | 22.44 (15.54, 29.33) |
-6.40 (-15.00, 2.196) |
9.39 (-4.03, 22.80) |
-19.44 (-35.51, -3.36) |
0.49 | 68.2 | 7.56 | 0.0010 |
Daphnia | 16.12 (12.68, 19.57) |
-3.61 (-5.24, -1.99) |
0.44 | 73.65 | 20.80 | 0.0001 | ||
Small cladocerans | 13.83 (9.99, 17.67) |
-3.87 (-6.20, -1.53) |
0.31 | 91.74 | 11.57 | 0.0022 | ||
Copepods | 19.73 (13.48, 25.97) |
-7.38 (-14.39, -0.37) |
0.15 | 112.32 | 4.69 | 0.0398 | ||
D) Return time (Control/Pulse metric) | ||||||||
Predictor | Intercept (95% CI) |
Slope (95% CI) |
Change in Int. (95% CI) |
Change in Slope (95% CI) |
R2 | MSE | F | P |
Total biomass | 27.01 (21.38, 32.64) |
-5.34 (-8.44, -2.24) |
0.33 | 76.43 | 12.53 | 0.0015 | ||
Cladoceran length | 25.07 (18.41, 31.74) |
-0.62 (-8.93, 7.70) |
6.01 (-6.96, 18.98) |
-19.62 (-35.16, -4.08) |
0.44 | 63.74 | 6.22 | 0.0028 |
Daphnia | 20.30 (16.69, 23.90) |
-2.69 (-4.39, -0.98) |
0.29 | 80.68 | 10.50 | 0.0033 | ||
Small cladocerans | 18.53 (14.79, 22.27) |
-3.12 (-5.39, -0.84) |
0.23 | 86.77 | 7.94 | 0.0091 | ||
Copepods | 25.51 (20.20, 30.81) |
-9.32 (-15.27, -3.37) |
0.28 | 81.02 | 10.35 | 0.0035 |
Notes: Biomass variables were log10(x + 0.01)-transformed to linearize relationships. Degrees of freedom for the F statistic were determined as P – 1 and 28 – P, where P is the number of parameters listed in each row of the table.