BISHOP ET AL : OXYGEN CONSUMPTION OF BROWN SHRIMP 



3-h periods (Table 1), but were not found to be 

 significantly different. The mean oxygen con- 

 sumption rates for individual shrimp during the 

 24-h test varied from 0.20 to 0.38 mg O2 g wet 

 h~' and were significantly different (Table 1). 



m 



Table 1. — Mean diurnal oxygen consumption rates (mg Oz-g 

 wet m"' • h' ) of five Penaeus aztecus: m = mass. 



' Differences among time periods not significant 

 ^Differences among shrimp fiigtily significant (P- 01) 



Light; Reduced Light Effects 



Mean oxygen consumption rates and standard 

 error for seven shrimp tested in light compared 

 with reduced light were 0.25±0.09 and 0.17±0.09 

 mg O2  g wet m ~^  h~^ and were not found to differ 

 significantly. 



Disturbance Effects 



The mean oxygen consumption rate of 6.7 g 

 shrimp after disturbance was 0.56±0.05 mg O2 -g 

 wet m~^ h"^ and 4.3 times higher than that 

 (0.13 ±0.01 mg Oag wet m-^-h'^) for resting 

 shrimp. This difference was highly significant. 



Crowding Effects 



Mean oxygen consumption rates and standard 

 error for 3.7 g f! aztecus tested singly and in pairs 

 were 0.50±0.06 and 0.41±0.05 mg Oag wet 

 m~' -h"'. These differences were not found to be 

 significant. One or two 3.7 g shrimp in the test 

 chamber resulted in an average of 0.035 or 0.071 g 

 of shrimp cm"^ of chamber floor and 0.015 or 0.031 

 g of shrimp cm""^ of chamber volume. 



Mean oxygen consumption rates and standard 

 error of 6.7 gP. aztecus tested singly and in groups 

 of two, three, and four were 0.30±0.04, 0.37 ±0.02, 

 0.35±0.03, and 0.29±0.02 mg O2 g wet m"^ h'^ 

 respectively. These differences were not statisti- 

 cally significant. One, two, three, or four 6.7 g 



shrimp in the test chamber represented 0.064, 

 0.126, 0.188, or 0.247 g of shrimp cm-^ and 0.028, 

 0.054, 0.081, or 0.107 g of shrimp cm~', respec- 

 tively. 



Size, SaHnity, and Temperature Effects 



In the factorial test, size and temperature were 

 the only significant main effects, but salinity-size 

 and salinity-temperature effects were significant 

 interactions. (Figure 1, Table 2). The smaller 



aztecus 





O) 



E 



IS 



23 28 



TEMPERATURE ("C) 



Figure 1. — Mean oxygen consumption rate of 3.7 and 6.7 g 

 Penaeus aztecus vs. temperature at salinities of 10, 20, and 30%o. 



shrimp consumed more oxygen per unit mass (0.44 

 mg O2  g wet m -1 • h-i ) than did the larger shrimp 

 (0.40 mg O2 g wet m~^ h-i), but this difference 

 was confined to salinities of 20%o as shown by the 

 salinity-size interaction (Figure 1, Tables 2, 3). In 

 20%o S, the 3.7 g shrimp consumed an average of 

 0.46 mgOj g wetm-i h-^ and the 6.7 g shrimp 

 consumed about 0.34 mg O2 g wet m ~J h"!. 



745 



