Modeling PCB-Bioaccumulation in the Bottlenose Dolphin (Tursiops truncatus): Estimating a Dietary Threshold Concentration

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

richards_etal_msat_genotypes

Corresponding DNA microsatellite (STR - short tandem repeart) genotypes for complete T. tursiops dataset, including geographic location of collections (Lat/Long) and gender of the source individual

Richards_et al_MtDNA haplotypes

Five unique mtDNA haplotypes found among 132 characterized bottlenose dolphin individuals. These sequences have also been deposited with GenBank under accession numbers KF366717-KF366721

richards_etal.msat_genotypes

Microsatellite DNA haplotype allele data generated by PCR amplification and genotyping. The following loci were genotyped as described - ev14, ff6, kwm12a, mk5, mk6, mk8, ppho130, ttr04, ttr19, ttr34, ttr48, ttr58, ttr63, txvt5, txvt

Nested general linear model, means, standard deviation (SD) for endocrine and catecholamine parameters for bottlenose dolphins from managed-care (Marine Mammal Program (MMP), Georgia Aquarium (GA) and wild populations (Indian River Lagoon (IRL), FL, Charleston (CHS), SC, adjusted for age and sex, by site.

<p>Nested general linear model, means, standard deviation (SD) for endocrine and catecholamine parameters for bottlenose dolphins from managed-care (Marine Mammal Program (MMP), Georgia Aquarium (GA) and wild populations (Indian River Lagoon (IRL), FL, Charleston (CHS), SC, adjusted for age and sex, by site.</p

Nested general linear model, means, standard deviation (SD) for protein electrophoresis for bottlenose dolphins from managed-care Georgia Aquarium (GA) and wild populations (Indian River Lagoon (IRL), FL, Charleston (CHS), SC, adjusted for age and sex, by site.

<p>Nested general linear model, means, standard deviation (SD) for protein electrophoresis for bottlenose dolphins from managed-care Georgia Aquarium (GA) and wild populations (Indian River Lagoon (IRL), FL, Charleston (CHS), SC, adjusted for age and sex, by site.</p

Gene transcript levels of measured cytokines from managed-care (Navy, Georgia Aquarium (GA)) and wild populations (Indian River Lagoon (IRL), FL, Charleston (CHS), SC), adjusted for age and sex, using a general linear model.

<p>Statistical differences between groups were found for the following five cytokines TNF, INFα, IL-4, IL-10, IRL2Rα (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0176202#pone.0176202.t005" target="_blank">Table 5</a> for statistical differences). Generally, higher transcript levels were found in wild dolphins versus one or both managed-care groups (note, the smaller the normalized value, the more a gene is transcribed, the larger the normalized value, the less a gene is transcribed).</p

Means and standard deviation of antibody titers to marine bacteria from managed-care (Navy, Georgia Aquarium (GA)) and wild populations (Indian River Lagoon (IRL), FL, Charleston (CHS), SC), adjusted for age and sex, using a general linear model.

<p>For all antibodies, significantly higher titers were found in wild dolphins compared to one or more of the managed dolphin groups (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0176202#pone.0176202.t005" target="_blank">Table 5</a> for statistical differences). No differences were observed between the two managed-care dolphin groups with their antibody titers to V. cholera and <i>M</i>. <i>marinarum</i> but differences occurred in the other three organisms (<i>E</i>. <i>rhusiopathiae</i>, <i>V</i>. <i>parahaemolyticus</i>, <i>E</i>.<i>coli</i>).</p

Nested general linear model, means, standard deviation (SD) for hematological parameters for bottlenose dolphins from managed-care (Marine Mammal Program (MMP) and Georgia Aquarium (GA)) and wild populations (Indian River Lagoon (IRL) and Charleston (CHS)), adjusted for age and sex, by site.

<p>Nested general linear model, means, standard deviation (SD) for hematological parameters for bottlenose dolphins from managed-care (Marine Mammal Program (MMP) and Georgia Aquarium (GA)) and wild populations (Indian River Lagoon (IRL) and Charleston (CHS)), adjusted for age and sex, by site.</p

Demographic data for bottlenose dolphins from managed-care (Marine Mammal Program (MMP), Georgia Aquarium (GA)) and wild populations (Indian River Lagoon (IRL), FL, Charleston (CHS), SC.).

<p>Demographic data for bottlenose dolphins from managed-care (Marine Mammal Program (MMP), Georgia Aquarium (GA)) and wild populations (Indian River Lagoon (IRL), FL, Charleston (CHS), SC.).</p