Anweiler et al.: Effects of temperature and hypoxia on the metabolic performance of Morone saxatilis 
343 
Ethical approval 
All applicable international, national, and institutional 
guidelines for the care and use of animals were followed. 
All procedures in this study involving animals were per¬ 
formed in accordance with the ethical standards of the 
institution or practice at which the procedures were con¬ 
ducted. Procedures used in this research were covered 
under College of Charleston Institutional Animal Care 
and Use Committee protocol 2016-01-29-081028. 
Results 
During all trials, the decrease in oxygen saturation in the 
chamber during the measurement period was linear (mean 
coefficient of determination [r 2 ]: 0.99 [SD 0.01]), indicating 
that the chamber had no leakage (Svendsen et al., 2016). 
The decrease in oxygen saturation observed while mea¬ 
suring background oxygen consumption was also linear 
(mean r 2 : 0.92 [SD 0.13]). Groups of fish used to compare 
among treatment temperatures had significantly different 
wet weights (F 246 =16.76,P<0.01),TL (F 2 46 =12.60,P<0.01), 
and Kn (F 2 46 =6.31, P<0.01) (Table 1), although these same 
factors were similar across all DO-concentration treat¬ 
ments (weight: F 24fi =0.50, P=0.61; TL: F 24fi =1.12, P=0.34; 
Kn: F 2 46 =1.05, P=0.36; Table 1). 
Strong linear relationships of the log of oxygen con¬ 
sumption on swimming speed allowed for calculation of 
SMR by extrapolation to zero for each individual (mean 
r 2 : 0.95 [SD 0.07]). The SMRs of striped bass were signifi¬ 
cantly different across temperatures, with the SMR at 
25°C being significantly lower than the SMR at 32°C and 
with the SMR at 20°C being intermediate and not signifi¬ 
cantly different from the SMRs at the other temperatures 
(Tables 1 and 2, Fig. 3A). Standard metabolic rate was 
not significantly affected by treatment DO concentration, 
the interaction of temperature and DO level, weight, or 
Kn (Table 2). The results were slightly different when DO 
concentration was replaced with P0 2 in the linear models: 
P0 2 was marginally negatively related to SMR (Table 2), 
and the SMR was higher for the 32°C treatment than for 
the 20°C and 25°C treatments. The models that used raw 
SMR were qualitatively similar (Table 2), with the excep¬ 
tion that fish wet weight was positively related to SMR as 
would be expected. 
The MMRs were significantly different across tempera¬ 
ture and DO-level treatments, although the interaction 
of these 2 factors was not significant (Table 2). The MMR 
at 20°C was significantly lower than the MMR at 32°C, 
and the MMR at 25°C was intermediate and not signifi¬ 
cantly different from the MMRs at other temperatures 
(Table 1, Fig. 3). The MMRs increased significantly with 
increasing DO concentration (Table 1, Fig. 3). Maximum 
metabolic rate was negatively related to Kn but not to 
weight (Table 2). When DO level was replaced with P0 2 
in the linear models, P0 2 was positively related and Kn 
was still negatively related to MMR. However, treatment 
Table 2 
Results from linear models used to test the effects of treatment temperature, dissolved oxygen (DO) concentration, partial pressure 
of oxygen (P0 2 ), fish wet weight, fish relative condition factor (Kn), and acclimation time of striped bass (Morone saxatilis) on stan¬ 
dard metabolic rate (SMR), maximum metabolic rate (MMR), aerobic metabolic scope (AMS), and exhaustion time. The top half of 
the table shows results for models with DO concentration at fixed-level treatments (2.5, 3.0, and 4.0 mg/L). The bottom half shows 
actual P0 2 in each treatment (a continuous variable). Values for SMR, MMR, and AMS were calculated by dividing oxygen con¬ 
sumption per hour by fish wet weight. Absolute or raw SMR, MMR, and AMS were calculated as metabolic rates not divided by fish 
wet weight. The degrees of freedom (df) numerator and denominator used to test each parameter in each model are separated by 
a comma. An alpha level of 0.05 was used to establish significance. Data used in models came from trials conducted at the Marine 
Resources Research Institute, South Carolina Department of Natural Resources, from June through December 2014. 
Model 
SMR 
MMR 
AMS 
Raw SMR 
Raw MMR 
Raw AMS 
Exhaustion 
time 
F 
P 
F 
P 
F 
P 
F 
P 
F 
P 
F 
P 
F 
P 
df 
Temperature 
8.55 
<0.01 
8.42 
<0.01 
4.02 
0.03 
9.18 
<0.01 
9.16 
<0.01 
4.21 
0.02 
3.13 
0.05 
2,39 
DO (mg/L) 
2.22 
0.12 
54.0 
<0.01 
72.4 
<0.01 
2.23 
0.12 
52.6 
<0.01 
71.8 
<0.01 
15.2 
<0.01 
2,39 
Temp*DO 
0.24 
0.91 
0.29 
0.88 
0.68 
0.61 
0.22 
0.92 
0.33 
0.86 
0.73 
0.58 
0.23 
0.92 
4,39 
Acclimation 
2.24 
0.14 
0.70 
0.41 
0.13 
0.72 
2.56 
0.12 
1.08 
0.31 
0.04 
0.85 
1.70 
0.20 
1,39 
Kn 
0.21 
0.65 
4.89 
0.03 
3.81 
0.06 
0.09 
0.76 
3.63 
0.06 
2.95 
0.09 
3.66 
0.06 
1,39 
Wet weight 
0.41 
0.53 
1.87 
0.18 
4.03 
0.05 
16.6 
<0.01 
26.1 
<0.01 
11.0 
<0.01 
5.70 
0.02 
1,39 
Temperature 
10.4 
<0.01 
0.85 
0.44 
0.69 
0.51 
11.2 
<0.01 
1.31 
0.28 
0.37 
0.69 
6.87 
<0.01 
2,42 
P0 2 (kPa) 
4.49 
0.04 
116 
<0.01 
150 
<0.01 
4.45 
0.04 
113 
<0.01 
148 
<0.01 
30.9 
<0.01 
1,42 
Temp*P0 2 
0.21 
0.77 
0.03 
0.97 
0.11 
0.90 
0.22 
0.81 
0.04 
0.96 
0.10 
0.91 
0.75 
0.48 
2,42 
Acclimation 
2.88 
0.10 
0.60 
0.44 
0.31 
0.58 
3.26 
0.08 
0.97 
0.33 
0.14 
0.71 
2.02 
0.16 
1,42 
Kn 
0.31 
0.58 
5.26 
0.03 
3.55 
0.07 
0.14 
0.71 
3.73 
0.06 
2.58 
0.12 
4.76 
0.03 
1,42 
Wet weight 
0.44 
0.51 
1.96 
0.17 
3.92 
0.05 
18.4 
<0.01 
30.9 
<0.01 
13.2 
<0.01 
5.44 
0.02 
1,42 
