In situ measurement of tissue turnover and energy conversion efficiencies in lake trout (Salvelinus namaycush) using a novel toxicokinetic approach

Abstract

We determined polychlorinated biphenyl (PCB) elimination patterns in lake trout (Salvelinus namaycush) from Lake Ontario using biomonitoring data collected from 1977 to 1993. The in situ elimination rates of these persistent pollutants were found to describe tissue turnover rates in lake trout. A model relating tissue turnover rates and endogenous energy conversion efficiencies revealed that chemical elimination in larger organisms is primarily regulated by food limitation and bioenergetic mechanisms rather than chemical kinetics. Lake trout approximately 2500 g and larger were observed to have higher PCB elimination rates than smaller fish as a result of increased lipid mobilization to supplement metabolic demands due to increased time spent foraging. This study concludes that the growth and production of large predators in Lake Ontario are regulated by the bioenergetic constraints of searching for prey in a foodlimited environment. We also demonstrate that persistent organic pollutant kinetics can describe the proportion of endogenous energy required to support metabolism and production, thus providing important in situ measurements of bioenergetic processes.Résumé : Des données de surveillance biologique de 1977 à 1993 nous ont servi à déterminer les patrons d'élimination des biphényls polychlorés (BPC) chez le touladi (Salvelinus namaycush) au lac Ontario. Les taux d'élimination sur place des ces polluants persistants représentent les taux de remplacement tissulaire chez le touladi. Un modèle qui met en relation les taux de remplacement tissulaire et les efficacités endogènes de conversion énergé-tique montre que l'élimination chimique chez les organismes de plus grande taille est principalement contrôlée par la limitation de nourriture et les mécanismes bioénergétiques que par la cinétique chimique. Les touladis d'environ 2500 g et de taille supérieure ont des taux d'élimination de BPC plus élevés que les poissons plus petits à cause d'une mobilisation plus forte des lipides pour assurer les besoins énergétiques requis par un temps plus long passé à la recherche de nourriture. Notre étude conclut que la croissance et la production des grands prédateurs dans le lac Ontario sont contrôlées par les contraintes bioénergétiques reliées à la recherche de proies dans un milieu où la nourriture est limitée. Nous démontrons aussi que la cinétique des polluants organiques persistants peut décrire la proportion de l'énergie endogène qui est requise pour supporter le métabolisme et la production, ce qui fournit des mesures in situ des processus bioénergétiques.[Traduit par la Rédaction] Paterson et al. 471

Trends of legacy and emerging-issue contaminants in Lake Simcoe fishes

“…Use of the decay model allows direct comparison of our results with those who have used a similar model in temporal trend studies in the Great Lakes (DeVault et al, 1996;French et al, 2006;Huestis et al, 1996;Paterson et al, 2005). This model is intrinsically linear when log-transformed and was estimated by ordinary least-squares linear regression (lnC t = lnC 0 + k 2 t).…”

“…This model is intrinsically linear when log-transformed and was estimated by ordinary least-squares linear regression (lnC t = lnC 0 + k 2 t). Individual concentration data for each time point were included to incorporate the variability of each year in our regression analysis, as recommended by Zar (1984), consistent with several previous studies (Hickey et al, 2006;Huestis et al, 1996;Paterson et al, 2005). However, temporal trend analysis using arithmetic means was also performed (DeVault et al, 1996;French et al, 2006), which led to similar results except that both r 2 and p-values were generally greater because the use of mean values does not incorporate variability within years and lowers the power associated with the tests.…”

Temporal and spatial trends of organochlorines and mercury in fishes from the St. Clair River/Lake St. Clair corridor, Canada

“…First, we used the common first-order exponential decay model (C t =C 0 e k2t ), where C 0 and C t are the concentrations initially and at time t (year), respectively, and k 2 is the apparent first-order rate constant, which allows direct comparison of our results with those who have used a similar model in temporal trend studies in the Great Lakes (DeVault et al, 1996;French et al, 2006;Huestis et al, 1996;Paterson et al, 2005). This model is intrinsically linear when log-transformed and was estimated by ordinary least-squares linear regression (lnC t =lnC 0 + k 2 t).…”

“…Contaminant trends in fish are often reflective of ambient conditions, although they also depend on changes in the food web, especially in top predatory species (DeVault et al, 1996;French et al, 2006;Paterson et al, 2005). However, with due consideration of food web processes, fish concentrations can be used as valuable indicators of what is occurring in the ambient environment.…”

Brominated and chlorinated flame retardants in Lake Ontario, Canada, lake trout (Salvelinus namaycush) between 1979 and 2004 and possible influences of food‐web changes

“…Toxicol. Programs monitoring a variety of species are important in examining temporal trends, because species like lake trout and herring gulls have different diets and bioenergetics and respond to changing ecosystem dynamics in different ways [20,21]. 28, 2009 911 mulates contaminants to detectable concentrations and integrates exposure through its food web [17,18].…”