Oxygen consumption and ammonia excretion of Xiphopenaeus kroyeri Heller (Penaeidae) in relation to mass temperature and experimental procedures Shrimp oxygen uptake and ammonia excretion

Xiphopenaeus kroyeri (Heller, 1862) is important to the shrimp fishery in Brazil and is one of the main contributors to the benthic megafauna biomass in Sao Paulo State littoral coast. Routine metabolic (R) and ammonia-N (U) excretion rates, defined as those measured during minimum but uncontrolled activity, were quantified in this shrimp at five different temperatures (20, 22, 25, 28 and 30 degrees C) in a flow through system. The animals rapidly achieved uniform rates, showing little handling stress, which may represent an experimental artifact that is responsible for wide variations in the measurement of routine rates. A circadian rhythm of R and U rates was detected, as they were significantly higher during dark conditions. The following predictive equations relating R and U rates, body mass and temperature during the day were developed: R = e((3.66+0.078T))M(0.849), U = e((5.34+0.083T))M(0.880) [R (mu l O-2 . h(-1)); U (nmol N-NH4+. h(-1)); M (g wet weight); T (degrees C)]. These equations can be used to estimate both parameters in the species general energy budget. Q(10) values obtained in this study are in the range normally found for crustaceans, and O:N ratios showed that the seabob has a protein dominated metabolism in postabsortive stage at all tested temperatures. Copyright (C) 1997 Elsevier Science B.V.