Radioisotope Turnover and Energy Flow in Terrestial Isopod Populations

Abstract

Radiocesium turnover rates in terrestrial isopod populations were used to measure food consumption and metabolism under natural and laboratory—simulated field conditions. Four old—field and forest species were studied: Armadillidium vulgare (Latreille), Armadillidium nasatum Budde—Lund, Cylisticus convexus (DeGeer), and Metoponorthus pruinosus (Brandt). Uptake, body burden equilibria, and elimination rates for 134Cs were related to environmental temperatures (Q10°2). dietary supplements of stable Na, K, and Cs salts produced no effect upon 134Cs elimination rates. Assimilation fractions from food were 60 to 64% for digestible dry matter, 70 to 73% for caloric intake, and 70 to 87% for radiocesium. Body equilibrium concentrations and biological half—lives of radiocesium in each species permitted estimates of food consumption comparable to gravimetric determinations. Food intake varied between different species and ranged from 1.5 to 3.5% of dry body weight per day. Bomb calorimetry and respirometry measurements were used to partition the total energy budgets, caloric inputs required for maintenance, production, and growth were determined. Radiocesium elimination rates were correlated with the metabolic rates of individual species, and radionuclide turnover rates in tagged individuals were demonstrated to be a practicable means of determining the activity and metabolism of species in the natural habitats.

Biokinetics of selected heavy metals and radionuclides in the common Mediterranean echinoid Paracentrotus lividus: sea water and food exposures

“…Linearity was systematically tested by a linearity test for regression with replication (Zar 1984). If radiotracer losses displayed an exponential shape, the kinetics were described either by a single-component exponential model where h is the biological depuration rate constant (d-l) and allows the calculation of the radiotracer biological half-life (T1,1,2 = In2/)L), or by a 2-component exponential model where the 'S' subscript refers to a short-lived component (S component) while the '1' subscript refers to a long-lived component (1 component) (Hubbell et al 1965, Reichle 1967, Reichle e t al. 1970, Whicker & Schultz 1982).…”

“…1970, Whicker & Schultz 1982). The exponential model showing the is an estimate of the fraction of radioactivity assimibest fitting accuracy (decision based on calculation of lated from food (Reichle 1967, Fowler & Guary 1977, the coefficients of dertermination, R2, and examination Miramand et al 1982). A biological half-life may be of the residuals) was then selected.…”

“…calculated for both short-and long-lived components Considering the 2-component exponential model, (TblIls a n d Tb1,21) using the corresponding depuration the short-lived component is a model for the loss of the rate constants (h, or ?L,, respectively) (Hubbell et al proportion of radiotracer pool that is weakly associated 1965, Reichle 1967, Reichle et al 1970, Whicker & with the organism. while the long-lived component is a Schultz 1982).…”

Allometric Relationship of Postmolt Net Ion Uptake, Ventilation, and Circulation in the Freshwater CrayfishProcambarus clarkii: Intraspecific Scaling

“…Second, the majority of existing studies have focused on metabolic rate or anatomical features that can be easily measured. Third, much of the existing data have been interspecific since most species do not cover several orders of magnitude in size during the course of their life history (exceptions: Weymouth et al 1944;Reichle 1967;Bicudo 1986;Wheatly 1989). Therefore, the goal of this article was to rectify these deficiencies by examining intraspecific allometry of ion flux, ventilation, and circulation in the freshwater crayfish, Procambarus clarkii (Girard).…”

U.S. Radioecology Research Programs of the Atomic Energy Commission in the 1950s

“…The insects consumed approximately 6% of the plant biomass during a growing season. A new radiological technique was now available to measure herbivory and predation in natural ecosystems (Reichle 1967;Reichle and Crossley 1967 The pits were both operational and experimental at the same time. They were experimental in that they were located in a shale formation, which had been found to have high sorptive properties for a number of fission products and therefore was being considered for a possible approach to dealing with large volumes of liquid wastes.…”