OXYGEN CONSUMPTION AND HEMOLYMPH OSMOLALITY OF 

 BROWN SHRIMP, PENAEUS AZTECUS 



James M. Bishop, > James G. Gosselink,^ and James H. Stone^ 



ABSTRACT 



Oxygen consumption and (or) osmoregulation of brown shrimp was measured under conditions appli- 

 cable to their natural environment or culture. Shrimp were acclimated to test salinity and temperature 

 a minimum of 1 week prior to any test and to the respirometer chamber for 1 hour prior to recording 

 data. Time of day, effects of white-light illumination, and crowding were not found to influence 

 significantly their mass ( m) specific oxygen consumption rate (mg O2  g wet m • h ); however, 

 disturbedshrimpconsumedoxygennearly four times faster than shrimp at rest (0.56 vs. 0.13 mg02  g 

 wet m ~ ' • h ~ ' ). The effects of size (3.7 and 6.7 g shrimp), salinity (10, 20, and 30% ), and temperature 

 (18°, 23°, 28°, 33° C) on shrimp hemolymph concentrations and oxygen consumption rates showed 

 that hemolymph osmolalities increased significantly with salinity and that oxygen consumption 

 rates increased significantly with temperature. Mean hemolymph concentrations in 10, 20, and 30%o 

 salinity were 616, 696, and 774 milliosmoles, but differences among oxygen consumption rates in 

 these salinities were negligible, supporting the hypothesis that relatively little energy is required 

 for osmoregulation by euryhaline species. Mean hemolymph concentrations were significantly higher 

 for 3.7 g shrimp (796 milliosmoles) than for 6.7 g shrimp (753 milliosmoles) only 30?. salinity, indi- 

 cating that the larger shrimp may be better hypoosmoregulators. At 18° C, oxygen consumption 

 rates averaged 0.29 mg O2 • g wet m ' • h ' and increased significantly at each test temperature 

 to 0.55 mg O2  g wet m ' • h ~' at 33° C. Indirect calorimetry calculations showed that juvenile 

 shrimp (~5.2 g) in 10-30% salinity and 23°-28° C respired a daily equivalent approximating 3.4% of 

 their energy content, that is, 105 calories. 



Shrimp comprise the basis for the nation's most 

 valuable seafood industry (Roedel 1973). Demand 

 has surpassed domestic production, and in 1975 

 the United States imported about 37% of its an- 

 nual consumption (National Marine Fisheries 

 Service 1978). Demand and high pound value have 

 made shrimp an attractive species for culture 

 ( Rose et al. 1975 ). Although slirimp iPenaeus spp. ) 

 culture is biologically possible, no operations have 

 been economically successful in the United States. 

 Reasons for this, in part, are that in spite of years 

 of study, many basic aspects of shrimp behavior, 

 biology, and physiology remain unknown. Fun- 

 damental to intensive husbandry of any animal is 

 knowledge of its energy budget, i.e., its consump- 

 tion and utilization of energy under specified con- 

 ditions. 



Energy budgets are usually depicted as flow 

 schemes and diagrammatically trace energy de- 

 rived from food to expenditures in various 



^Marine Resources Research Institute, South Carolina 

 Wildlife and Marine Resources Department, P.O. Box 12559, 

 Charieston, SC 29412. 



^Center for Wetland Resources, Louisiana State University, 

 Baton Rouge, LA 70803. 



Manuscript accepted March 1980. 



FISHERY BULLETIN: VOL. 78, NO. 3, 1980. 



physiological processes (see Brody 1945; Harris 

 1966; Crampton and Harris 1969; Brett 1970). The 

 amount of energy channelled through an or- 

 ganism and the compartmentalization of that 

 energy depends upon environmental and 

 physiological variables such as season, tempera- 

 ture, photoperiod, salinity, sex, size, age, food, 

 crowding, stage of molt cycle, etc. (Zeuthen 1947; 

 Waterman 1960; Prosser and Brown 1961; 

 Crampton and Harris 1969; Brett 1970). Because 

 metabolic demands of maintenance and feeding 

 activity must be satisfied before growth can occur, 

 knowledge of these demands under various condi- 

 tions may be used advantageously to control or 

 manipulate food conversion (Brett 1970). Most as- 

 similated energy is expended in basal metabolism 

 and maintenance (Brody 1945). 



Internal respiration or intermediary metabo- 

 lism is the sum of enzymatic reactions in which 

 energy is made available for biological work (Pros- 

 ser and Brown 1961), and the best measure of 

 metabolism is caloric output (Fry 1957). Obtain- 

 ing the caloric output for an experimental or- 

 ganism requires the determination of its oxygen 

 consumption, carbon dioxide production, nitrogen 

 excretion, and the caloric content of excreta (Fry 



741 



