Rapid 13C/12C turnover during growth of brown shrimp (Penaeus aztecus)

Abstract

Using natural-abundance C/C ratios as tracers, carbon turnover rates were determined for postlarval brown shrimp, Penaeus aztecus, in five laboratory growth experiments. Although tissue turnover in adult animals generally occurs during maintenance metabolism and is a function of time, turnover for young postlarval shrimp was accelerated during growth, and was primarily a function of weight gained rather than time. Metabolic loss of tissue carbon during growth was usually approximated by the function, Fraction lost=1-(initial weight/final weight). For shrimp that switch diets in the sea, model calculations show that this high turnover rate coupled with a four-fold weight increase suffices for shrimp to achieve a close isotopic resemblance of 1‰ or less (δC units) to the new diet.In accordance with these predictive calculations, shrimp which had increased in weight by a factor of four or more in the culture experiments showed essentially constant isotopic values reflecting their new diets. For these larger animals, the average animal-diet difference varied across three diets from-0.9 to +11‰, and the δC range among individuals was ≦1.4‰ in each experiment.

Application of stable isotope analysis to differentiate shrimp extracted by industrial fishing or produced through aquaculture practices

“…Penaeid shrimps are highly mobile organisms and change their feeding habits as a function of the available trophic items in their feeding niches. Despite these fast trophic changes, previous studies conducted in laboratory have demonstrated that shrimps rapidly achieve isotopic equilibrium with their diets and reflect the isotopic value of the available preys or feeding items over a period of 2-3 weeks (Fry and Arnold 1982;Gamboa-Delgado et al 2011). In the present study, the observed poor correlation (R 2 ranged from 0.07 to 0.16) between individual shrimp mass and isotopic values of samples of the same wild origin indicate that animals having different sizes were probably feeding on similar trophic elements.…”

Naturally-occurring stable isotopes as direct measures of larval feeding efficiency, nutrient incorporation and turnover

“…Protein synthesis studies in trout (Oncorhynchus mykiss) have shown that results obtained using enriched stable isotopes are similar to those obtained using radio-labelled amino-acids (Houlihan et al, 1995a). Carter et al (1994Carter et al ( , 1998 (Fry and Arnold, 1982;Al-Maslamani, 2006;GamboaDelgado and Le Vay, 2009b). This is due to the very fast growth rates characteristic of early life stages, so that observed carbon and nitrogen isotopic changes in larvae are thus mainly due to tissue accretion and not to tissue metabolic turnover, the converse of typical observations in adult organisms (Martinez de Rio et al, 2009).…”

“…This is due to the very fast growth rates characteristic of early life stages, so that observed carbon and nitrogen isotopic changes in larvae are thus mainly due to tissue accretion and not to tissue metabolic turnover, the converse of typical observations in adult organisms (Martinez de Rio et al, 2009). Exponential models applied to associate isotopic changes with time (or biomass increase) can also be used to assess elemental turnover rates (Fry and Arnold, 1982;Hesslein et al, 1993). As is also the case for isotopic mixing models (see following section), the resolution of such models in the estimation of elemental turnover rates and elemental t 50 is improved, with better fit to vannamei has the advantage of distinguishing between isotopic change due to metabolic turnover (m) and that due to isotopic dilution through growth (k).…”

“…Similarly, Herzka et al (2001) applied a model proposed by Fry and Arnold (1982) to estimate the relative influence of growth dilution and metabolic turnover components of isotopic tissue changes in larvae of red drum, Sciaenops ocellatus, resulting from habitat changes at settlement. Table 3 presents examples of estimated carbon and nitrogen turnover rates and metabolic elemental half times in tissue using stable isotopes at natural abundance levels in larval and post-larval fish and crustaceans.…”

Turnover rates of nitrogen stable isotopes in the salt marsh mummichog, Fundulus heteroclitus, following a laboratory diet switch

“…Atmospheric nitrogen gas was used as the standard. Stable isotope ratios are expressed as parts per thousand differences from this standard in the following equation (Peterson and Fry 1987 A c-value of -1 indicates turnover due only to growth (simple dilution) while c-values less than -1 represent proportionately greater contributions of metabolic turnover to overall isotopic change (Fry and Arnold 1982).…”