Modulation in Persistent Organic Pollutant Concentration and Profile by Prey Availability and Reproductive Status in Southern Resident Killer Whale Scat Samples

Persistent organic pollutants (POPs), specifically PCBs, PBDEs, and DDTs, in the marine environment are well documented, however accumulation and mobilization patterns at the top of the food-web are poorly understood. This study broadens the understanding of POPs in the endangered Southern Resident killer whale population by addressing modulation by prey availability and reproductive status, along with endocrine disrupting effects. A total of 140 killer whale scat samples collected from 54 unique whales across a 4 year sampling period (2010–2013) were analyzed for concentrations of POPs. Toxicant measures were linked to pod, age, and birth order in genotyped individuals, prey abundance using open-source test fishery data, and pregnancy status based on hormone indices from the same sample. Toxicant concentrations were highest and had the greatest potential for toxicity when prey abundance was the lowest. In addition, these toxicants were likely from endogenous lipid stores. Bioaccumulation of POPs increased with age, with the exception of presumed nulliparous females. The exceptional pattern may be explained by females experiencing unobserved neonatal loss. Transfer of POPs through mobilization of endogenous lipid stores during lactation was highest for first-borns with diminished transfer to subsequent calves. Contrary to expectation, POP concentrations did not demonstrate an associated disruption of thyroid hormone, although this association may have been masked by impacts of prey abundance on thyroid hormone concentrations. The noninvasive method for measuring POP concentrations in killer whales through scat employed in this study may improve toxicant monitoring in the marine environment and promote conservation efforts

Assimilation Efficiency of PBDE Congeners in Chinook Salmon

Polybrominated diphenyl ether (PBDE) flame retardants are environmental contaminants that can accumulate in biota. PBDE accumulation in an organism depends on exposure, assimilation efficiency, and elimination/metabolism. Net assimilation efficiency represents the fraction of the contaminant that is retained in the organism after exposure. In the present study, congener-specific estimates of net PBDE assimilation efficiencies were calculated from dietary exposures of juvenile Chinook salmon. The fish were exposed to one to eight PBDE congeners up to 1500 ng total PBDEs/g food. Mean assimilation efficiencies varied from 0.32 to 0.50 for BDE congeners 28, 47, 99, 100, 153, and 154. The assimilation efficiency of BDE49 was significantly greater than 100%, suggesting biotransformation from higher brominated congeners. Whole body concentrations of BDE49 significantly increased with both exposure to increasing concentrations of BDE99 and decreasing fish lipid levels, implying lipid-influenced debromination of BDE99 to BDE49. Excluding BDE49, PBDE assimilation efficiency was not significantly related to the numbers of congeners in the diets, or congener hydrophobicity, but was greater in foods with higher lipid levels. Estimates of PBDE assimilation efficiency can be used in bioaccumulation models to assess threats from PBDE exposure to Chinook salmon health and recovery efforts, as well as to their predators

Using Domestic and Free-Ranging Arctic Canid Models for Environmental Molecular Toxicology Research

The use of sentinel species for population and ecosystem health assessments has been advocated as part of a One Health perspective. The Arctic is experiencing rapid change, including climate and environmental shifts, as well as increased resource development, which will alter exposure of biota to environmental agents of disease. Arctic canid species have wide geographic ranges and feeding ecologies and are often exposed to high concentrations of both terrestrial and marine-based contaminants. The domestic dog (Canis lupus familiaris) has been used in biomedical research for a number of years and has been advocated as a sentinel for human health due to its proximity to humans and, in some instances, similar diet. Exploiting the potential of molecular tools for describing the toxicogenomics of Arctic canids is critical for their development as biomedical models as well as environmental sentinels. Here, we present three approaches analyzing toxicogenomics of Arctic contaminants in both domestic and free-ranging canids (Arctic fox, Vulpes lagopus). We describe a number of confounding variables that must be addressed when conducting toxicogenomics studies in canid and other mammalian models. The ability for canids to act as models for Arctic molecular toxicology research is unique and significant for advancing our understanding and expanding the tool box for assessing the changing landscape of environmental agents of disease in the Arctic

Fig 2 -

Concentrations of focal contaminants in Fucus spp. and Nereocystis at Salish Sea sites from the southernmost sites (left) to the northernmost sites (right). Bars are concentrations of a) Σ40PCBs (μg.kg-1 DW), b) benzo[a]-pyrene (BaP, μg.kg-1DW), c) total arsenic (mg.kg-1 DW), d) cadmium (mg.kg-1 DW), e) lead (mg.kg-1 DW), and f) total mercury (mg.kg-1 DW) calculated using the limit of quantification (LOQ)/2 when measured values were less than the LOQ. Upper ends of the vertical lines in a) are the calculated Σ40PCB concentrations when the LOQ was used for concentrations that were less than the LOQ. Lower ends of the bars are calculated values obtained when zero was used for the values less the LOQ. For a) Σ40PCBs and b) benzo[a]-pyrene, black dashed horizontal lines indicate the cancer slope factor-based screening levels (SLCSF). For c) total As, d) Cd, e) Pb, and f) total mercury, the upper black dashed horizontal line is the highest international limit (see Table 1) for the contaminant, and the lower black dashed horizontal line, if present, indicates the lowest international limit. Red and orange bars are concentrations in Fucus distichus that exceed or are less than the LOQ, respectively; yellow hatched bars or white hatched bars are concentrations in Fucus spiralis that exceed or are less than the LOQ, respectively; green cross-hatched or blue cross-hatched bars are concentrations in Nereocystis luetkeana that exceed or are less than the LOQ, respectively. Site codes are as in Fig 1.</p

Concentrations (in mg^.kg^-1 DW) of a) total arsenic (As), b) cadmium (Cd), and c) total mercury (Hg) in <i>Fucus distichus</i> (FD) and <i>Nereocystis luetkeana</i> (NL) at sites where both species were collected (N = 16).

Data are means ± 1 SD. Concentrations are significantly (PN. luetkeana than F. distichus for all three metals (paired t-tests).</p

References cited in supporting information.

(DOCX)</p

Comparisons of a) Σ₄₀PCBs, b) benzo[<i>a</i>]-pyrene, c) total arsenic, d) cadmium, e) lead, and f) mercury in <i>F</i>. <i>distichus</i> (red bars) and <i>N</i>. <i>luetkeana</i> (green bars) to commonly consumed foods.

Sites for which contaminant concentrations exceeded the mean + 2SD are shown separately. Bars labeled as F. distichus or N. luetkeana are mean concentrations (+ 1SD) from all sites that do not exceed the mean + 2SD. *Means that excluded sites with values greater than the mean + 2SD. Data for commonly consumed foods were obtained from [59–62]. More information about commonly consumed foods and the sources for this data are provided in S3 Table.</p

Calculations of totals for relevant organic chemicals presented in S1 Table.

(DOCX)</p

Recommended consumption rates (g DW/day).

Based on concentrations of Cd, Hg, Pb, benzo[a]pyrene (BaP), the sum of 40 PCB congeners (Σ40PCBs), and estimated total PCBs (ET-PCBs) calculated using the method of West et al. (2017) for each site where Fucus distichus (FD) and Fucus spiralis (FS) were collected. Bolded values are the lowest for a species at a particular site if the lowest value is less than 5 g dry weight/day. Values in parentheses below contaminant types are screening levels based on USEPA CSFs (PCBs and BaP) or RfDs (Cd and methyl Hg). The French limit for Pb was used as USEPA RfDs for Pb have not been assigned. Σ40PCB values were based on calculations that used ½ the LOQ when values were less than the LOQ. * Consumption rates that are lower using West et al.’s method [48] for estimating total PCBs relative to the sum of the 40 PCB congeners. ¥ Consumption rates that are higher using West et al.’s (2017) method for estimating total PCBs relative to the sum of the 40 PCB congeners. Site codes are as in Fig 1. (PDF)</p

Sites sampled in the Salish Sea.

AB: Agate Beach, AS: Ambleside, BB: Botanical Beach, BM: Britannia Mine, BR: Brothers Islands/Duntze Head, CA: Cape Mudge, CB: Coles Bay, CH: Camano Head, CI: Chatham Islands/Tl’chés, CM: Crofton Mill, DB: Deep Bay, DP: Duke Point Industrial Park, EF: Elk Falls Pulp Mill, CR: Campbell River, EH: Esquimalt Harbour, ES: East Sound, FW: Fresh Water Bay, FB: Fidalgo Bay Aquatic Reserve, FM: Four-Mile Rock, FR: Fort Rod Hill, GM: Goodridge Mill, PO: Portage Inlet HB: Hagan Bight, JB: Jefferson Beach, KB: Kulleet Bay, LT: Lone Tree Point, MF: Mukilteo Ferry, PA: Port Angeles, PE: Port of Everett, PH: Point Hope Shipyard, PI: Penelakut Island, PP: Post Point, PO: Portage Inlet, RB: Rock Bay, RW: Ruston Way, SB: Sooke Bay, SC: Smith Cove, SI: Senanus Island, SN: Sansum Narrows, SQ: Squaxin Island, TJ: Tsawwassen Jetty, VI: Vashon Island, VJ: Victoria Jetty, WP: Waterman Point, WG: Wing Point. Red circles indicate sites where only F. distichus were sampled, blue circles indicate sites where only F. spiralis were sampled, green squares indicate sites where only N. luetkeana were sampled, and green triangles indicate sites where both F. distichus and N. luetkeana were sampled.</p