344 
Fishery Bulletin 117(4) 
DO level (mg/L) 2.5 3.0 4.0 
ABC 
Temperature (°C) 
Temperature (°C) 
Figure 3 
Temperature (°C) 
Effects of temperature and dissolved oxygen (DO) level on (A) standard metabolic rate (SMR), (B) maximum 
metabolic rate (MMR), and (C) aerobic metabolic scope (AMS) of juvenile striped bass (Morone saxatilis) 
during trials conducted in aquarium tanks at the Marine Resources Research Institute, South Carolina 
Department of Natural Resources, from June through December 2014. Error bars indicate standard errors 
of the mean. 
temperature was no longer related to MMR (Table 2). The 
results were similar when these analyses were run with 
raw MMR as the response, except that the MMR at 32°C 
was significantly greater than the MMRs at both 20°C and 
25°C, Kyi was not related to raw MMR, and weight was 
positively related to raw MMR (Table 2). 
The values of AMS were significantly different across 
temperatures and DO levels, although the interaction 
between treatments was not significant (Table 2). The AMS 
at 20°C was significantly lower than the AMS at 32°C, and 
the AMS at 25°C was intermediate and not significantly dif¬ 
ferent from the AMS values at other temperatures (Table 1, 
Fig. 3). The AMS values increased with increasing DO con¬ 
centration (Table 1, Fig. 3). Aerobic metabolic rate was neg¬ 
atively related to weight but was not related to Kn (Table 2). 
The results were similar when DO level was replaced with 
P0 2 in the linear model, except that treatment tempera¬ 
ture was no longer related to AMS and P0 2 was positively 
related to AMS (Table 2). The results were similar when 
raw AMS was used as the response, except that fish wet 
weight was positively related to AMS (Table 2). 
Exhaustion time was significantly different across DO 
levels (Table 2). Fish in the 4.0-mg/L treatment had sig¬ 
nificantly longer exhaustion times compared with fish in 
the 3.0-mg/L and 2.5-mg/L treatments (Table 1). Neither 
temperature nor the interaction between treatments 
were significant terms in the model (Table 2). Exhaustion 
time was positively related to fish wet weight (Table 2). 
When DO concentration was replaced with P0 2 in the 
linear model, P0 2 and fish wet weight were both posi¬ 
tively related to exhaustion time and Kn was negatively 
related to exhaustion time. Treatment temperature was 
a significant predictor of exhaustion time when P0 2 was 
used (Table 2), with exhaustion times significantly longer 
at 25°C than at 32°C and with exhaustion time at 20°C 
being intermediate and not significantly different from 
the exhaustion times at 25°C or 32°C. 
Discussion 
This study is the first to investigate the effects of tempera¬ 
ture and DO concentration on the metabolism of striped 
bass in coastal waters of the southeastern United States. 
Within the range tested, SMR was greatest at 32°C. The 
SMRs increased with increasing temperature at DO levels 
of 3.0 and 4.0 mg/L (Fig. 2), supporting our first prediction. 
Notably, at a DO concentration of 2.5 mg/L, SMR was low¬ 
est at 25°C, a result that may have been influenced by high 
variability and small sample size. The MMRs increased 
with increasing temperature at all DO levels. Contrary to 
our second prediction, MMR was highest at 32°C at every 
DO level. The increase in both SMR and AMS with tem¬ 
perature caused a net increase in AMS across tempera¬ 
ture. Again, contrary to predictions, AMS was highest at 
32°C. Although increases in SMR and MMR are predicted 
within a normal temperature range, the magnitude of 
these changes was lower than expected. The Q 10 tempera¬ 
ture coefficient is a measure of the rate of change of a pro¬ 
cess as a consequence of increasing the temperature by 
10°C. In a normal temperature range, Q 10 values of 2-3 are 
expected, but in this study a Q 10 value of approximately 
1.3 was observed for SMR and MMR. The relatively par¬ 
allel changes in SMR and MMR led to a Q 10 value of 1.2 
for AMS, indicating wide thermal breadth for striped bass 
in the study area. This result may indicate that southern 
stocks of striped bass are well equipped to cope with tem¬ 
perature fluctuations, which are common in their estua¬ 
rine habitat. 
The results of previous studies of northern populations 
of striped bass indicate an optimum temperature in the 
mid-20s (degrees Celsius) (Coutant and Carrol, 1980; 
Coutant et al., 1984) and a lethal temperature in the lower 
30s (degrees Celsius), depending on life stage (Tagatz 4 ; 
Gift, 1970). These findings indicate that our highest treat¬ 
ment temperature (32°C) may be approaching the lethal 
