Search

A fundamental assumption of biotelemetry studies is that there are no adverse consequences from the surgical implantation or presence of the acoustic transmitter. In fisheries, most studies have evaluated this assumption over only short time periods (<2 years) in a laboratory setting. Here we compared the survival, growth, and body condition of populations of lake trout (Salvelinus namaycush) in three lakes containing tagged and untagged individuals over a 12-year period (2002–2013). We found no significant negative effects of acoustic telemetry tagging on the long-term survival of fish (estimates of combined annual survival ranged from 67% to 91%) and no negative effect of surgical implantation on growth or body condition for fish of either sex. Additionally, we found no significant effect of transmitter:fish mass ratio on fish survival, growth (with the exception of smaller-bodied fish in one lake), or condition. Our results indicate the use of transmitters weighing <1.25% (in water) of fish mass is a desirable criterion for larger-bodied adult lake trout. Our findings support the assumption that long-lived fish species tagged with acoustic transmitters via intracoelomic surgery survive, grow, and maintain body condition similar to untagged conspecifics over the long term in the wild. [ABSTRACT FROM AUTHOR]

An individually based (IB) model to predict PCB concentrations in the bottlenose dolphin population of Charleston, SC, USA, was developed with the aim to gain a better understanding of the bioaccumulation behavior and health risk of dietary PCBs across the population and their prey. PCB concentrations predicted in male and female bottlenose dolphin were in good agreement with observed tissue concentrations corroborating the reliability of the model performance and its utility in gaining a more complete view of risk. The modeled cumulative distribution of ΣPCB concentrations for the population with a breakdown into juvenile, adult male, and female subclasses ranged from 3600 to 144,400 ng/g lipid with 66% to >80% of the population exceeding the established threshold for adverse health effects of 17,000 ng/g lipid. The model estimated that a dietary PCB concentration not exceeding 5.1 ng/g wet wt would be required to reach a condition where 95% of the population would have tissue levels below the health effect threshold. The IB model for PCBs in bottlenose dolphins provides a novel approach to estimating the maximum acceptable dietary concentration for PCBs, a central and important factor to protect these apex predators. The model also enables effective prediction of concentrations in dolphins from fish contaminant surveys which are logistically easier and less costly to collect. [ABSTRACT FROM AUTHOR]

Polychiorinated biphenyl (PCB) concentrations declined rapidly in environmental compartments and most biota following implementation of regulations in the 1970s. However, the metabolic recalcitrance of PCBs may delay responses to such declines in large, long-lived species, such as the endangered and highly PCB-contaminated resident killer whales (Orcinus orca) of the Northeastern Pacific Ocean. To investigate the influence of life history on PCB-related health risks, we developed models to estimate PCB concentrations in killer whales during the period from 1930 forward to 2030, both within a lifetime (~50 years) and across generations, and then evaluated these in the context of health effects thresholds established for marine mammals. Modeled PCB concentrations in killer whales responded slowly to changes in loadings to the environment as evidenced by slower accumulation and lower magnitude increases in PCB concentrations relative to prey, and a delayed decline that was particularly evident in adult males. Since PCBs attained peak levels well above the effects threshold (17 mg/kg lipid) in ~1969, estimated concentrations in both the northern and the more contaminated southern resident populations have declined gradually. Projections suggest that the northern resident population could largely fall below the threshold concentration by 2030 while the endangered southern residents may not do so until at least 2063. Long-lived aquatic mammals are therefore not protected from PCBs by current dietary residue guidelines. [ABSTRACT FROM AUTHOR]

Abstract: Individual- and population-based models were developed to simulate the bioaccumulation of persistent organic pollutants (POPs) over the lifetime of ringed seals (Phoca hispida) and account for the effects of age, growth, body condition and sex (including gestation, birth and lactation). Lactational transfer was described using a milk to blubber partition coefficient, which was shown to be a function of K ow (K MB =1/(1.676+1.293·10−7 ·Kow) r 2 =0.60, n =32, p <0.001). Simulations showed that nursing mothers could transfer between 5% and 40% of their burden of low and high K MB contaminants, respectively, to their milk over 40 days of lactation. The models were calibrated using a POPs dataset for 50 seals (29 males, 21 females) from Arviat, Nunavut. They were initially calibrated for a group of eight highly recalcitrant PCB congeners (e.g. PCBs 153, 180) assuming a baseline elimination rate (k e) of about 0.03 year−1. For congeners more prone to biotransformation a satisfactory fit could only be reached by iteratively increasing k e to values ranging from 0.05 to 2.5 year−1 for PCBs 187 and 18, respectively; thus the models became a means for estimating k e. Estimated k e values were correlated with a calculated index of susceptibility to biotransformation (k e =0.0284/ R rel r 2 =0.98, n =20, p <0.001). This relationship was used to estimate k e values used in simulations to hind-cast temporal trends of ΣPCB, ΣDDT, ΣCHL, αHCH, βHCH in ringed seal populations and to predict potential future trends. Results of these simulations showed good agreement with measured concentrations in seals from two locations in the Canadian Arctic (Holman Island, NWT and Arctic Bay, Nunavut) collected between 1972 and 2001. The models show that the combined effects of rapid juvenile growth, a fast rate of population turnover and substantial capacity to eliminate many POPs result in fairly rapid responses to changes in contaminant loading, thus making ringed seals an effective choice for monitoring spatial and temporal trends of POPs in the Arctic marine ecosystem. [Copyright &y& Elsevier]

Concentrations of metals in hair are used often to develop pharmacokinetic models for both animals and humans. Although data on uptake are available, elimination kinetics are less well understood; stable isotope tracers provide an excellent tool for measuring uptake and elimination kinetics. In the present study, methylmercury concentrations through time were measured in the hair and blood of mink ( Neovison vison) during a controlled 60-d feeding experiment. Thirty-four mink were fed a standard fish-based diet for 14 d, at the end of which (day 0), 4 mink were sacrificed to determine baseline methylmercury (MeHg) concentrations. From day 0 to day 10, the remaining mink were fed a diet consisting of the base diet supplemented with 0.513 ± 0.013 µg Me199Hg/g and 0.163 ± 0.003 µg Me201Hg/g. From day 10 to day 60, mink were fed the base diet supplemented with 0.175 ± 0.024 µg Me201Hg/g. Animals were sacrificed periodically to determine accumulation of Me201Hg in blood and hair over the entire 60-d period and the elimination of Me199Hg over the last 50 d. Hair samples, collected from each mink and cut into 2.0-mm lengths, indicate that both isotopes of MeHg appeared in the hair closest to the skin at approximately day 10, with concentrations in the hair reaching steady state from day 39 onward. The elimination rate of Me199Hg from the blood was 0.05/d, and the ratio of MeHg in the hair to blood was 119. A large fraction of MeHg (22% to >100%) was stored in the hair, suggesting that in fur-bearing mammals the hair is a major route of elimination of MeHg from the body. Environ Toxicol Chem 2014;33:2873-2880. © 2014 SETAC [ABSTRACT FROM AUTHOR]

The development of an area-based polychlorinated biphenyl (PCB) food-web bioaccumulation model enabled a critical evaluation of the efficacy of sediment quality criteria and prey tissue residue guidelines in protecting fish-eating resident killer whales of British Columbia and adjacent waters. Model-predicted and observed PCB concentrations in resident killer whales and Chinook salmon were in good agreement, supporting the model's application for risk assessment and criteria development. Model application shows that PCB concentrations in the sediments from the resident killer whale's Critical Habitats and entire foraging range leads to PCB concentrations in most killer whales that exceed PCB toxicity threshold concentrations reported for marine mammals. Results further indicate that current PCB sediment quality and prey tissue residue criteria for fish-eating wildlife are not protective of killer whales and are not appropriate for assessing risks of PCB-contaminated sediments to high trophic level biota. We present a novel methodology for deriving sediment quality criteria and tissue residue guidelines that protect biota of high trophic levels under various PCB management scenarios. PCB concentrations in sediments and in prey that are deemed protective of resident killer whale health are much lower than current criteria values, underscoring the extreme vulnerability of high trophic level marine mammals to persistent and bioaccumulative contaminants. [ABSTRACT FROM AUTHOR]