Initial indications of polycyclic aromatic hydrocarbon exposure in Saskatchewan common loons

Common loons were captured from seven lakes within Meadow Lake Provincial Park in west–central Saskatchewan from 27 May to 5 June 2014 and 9–15 June 2015 (Fig. 1). Loons were caught using a suspended mist net with a loon decoy placed in the center (Uher-Koch et al. 2015). A playback of loon calls (yodel, tremolo, and wail) was used to lure individuals or pairs to the decoy. Captured loons were banded with a United States Geological Survey (USGS) aluminum band and a unique combination of plastic colored bands, enabling the individual identification of birds by field biologists during subsequent surveying. A suite of morphometric measurements was taken from captured individuals, including bill width, length, and depth, tarsal width and length, and mass. Blood samples were collected from the tibiotarsal vein to evaluate short-term Hg accumulation in individuals. Blood was drawn using a luer adapter directly into two 8 cc Vacutainers (Becton Dickinson, Franklin Lakes, New Jersey, USA) with sodium heparin. A total of 5–8 cc of blood was obtained from each individual. In addition, several capillary tubes were filled directly by placing them over the injection site. Upon filling, the ends were sealed (Critoseal, Fisher Scientific, Hampton, New Hampshire, USA).

To assess blood PAHs in 2014, several drops of blood were transferred to FTA cards (Fast Technology for Analysis of Nucleic Acids, GE Healthcare Life Sciences, Piscataway, New Jersey, USA) and placed in envelopes. To assess blood PAHs in 2015, 2–3 mL of blood were spun at 3000 rpm for 10 min and the plasma was decanted and frozen for analysis.

Feather samples, including one secondary feather from each wing, were collected to provide information on long-term Hg accumulation. To assess exposure to PAH during the winter period, four scapular feathers were collected in 2015 (scapular feathers were not obtained from loons in 2014). PAHs do not bioaccumulate, but their presence in feathers is indicative of circulating blood levels at the time of feather formation (C. Perkins, personal communication, 2014).

Standard laboratory protocols for analyzing total Hg in common loon tissues for blood and feathers as described by Evers et al. (1998) were followed. Analyses of blood and feather tissue samples were conducted at the Biodiversity Research Institute Laboratory (Gorham, Maine, USA). Analyses of blood and feather PAHs were previously described by Paruk et al. (2016), and were conducted at the University of Connecticut’s Center for Environmental Sciences and Engineering Laboratory. Sixteen parent PAHs were measured, as established by Keith and Telliard (1979) for the United States Environmental Protection Agency (phenanthrene, anthracene, naphthalene, acenaphthalene, fluorene, acenaphthene, fluoranthene, pyrene, chrysene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a,h)anthracene, indeno(1,2,3-cd)pyrene, and benzo(g,h,i)perylene).

To assess loon health, hematocrit was determined by placing 0.1 cc of blood in a hematocrit tube and spinning it for 7 min at 12 000 rpm using a hematocrit rotor. The percentage of whole blood vs. plasma was obtained using a hematocrit reader (Haefele et al. 2005). In addition, a full screening of blood chemistry for key health parameters was conducted in 2015 at the University of Miami Avian and Wildlife Laboratory (UMAWL). The UMAWL does a full range of screening, but for this study we focused on several key enzymes that are indicative of organ or tissue damage (aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), gamma glutamyl-transferase (GGT), and creatine phosphate (CPK).

Bird capture and handling methods complied with the guidelines of the American Ornithological Council on animal care under Environment Canada permit number #22636 and Institutional Animal Care and Use Committee permit number 042214-104.

Blood and feather Hg levels obtained from breeding common loons in Saskatchewan were compared with the Biodiversity Research Institute’s (briloon.org/) national loon mercury database. The database consists of blood and feather Hg levels obtained from over 5000 loons captured across North America. We used Paruk et al. (2016) to compare our blood PAH concentrations. This study examined blood PAHs obtained from common loons (n = 93) wintering off the Louisiana coast in an area that was heavily exposed to oil from the 2010 Deepwater Horizon oil spill. Blood chemistry data were compared with the only comparable data collected for 33 breeding loons from New York performed by the same lab (N. Schoch, personal communication, 2015).

Blood Hg values for all loons captured were low (<1.0 μg/g; Table 1), as established by Evers et al. (2008). Blood Hg concentrations reflect the near-term availability (i.e., days of exposure) of methylmercury in prey items. Loons are excellent indicators of Hg contamination (Evers et al. 2008); thus, the low Hg levels observed in the loons at Meadow Lake Provincial Park suggest that atmospheric fallout from anthropogenic and natural sources was low at this time.

One male loon captured 30 May 2014 on Mistohay Lake had a blood PAH value of 120 ng/g (Table 1). Based on blood PAHs levels obtained from common loons wintering off the Louisiana coast in an area that was heavily exposed to oil from the 2010 Deepwater Horizon oil spill (range 0–270.2 ng/g; Paruk et al. 2016), this level is considered high. Most birds can rapidly metabolize PAHs (<2 weeks) because of a well-developed mixed-function hepatic oxygenase system (Albers 2006). As spring migration takes 6–8 weeks for breeding Saskatchewan loons (Paruk et al. 2014a, 2014b), any PAHs they may have received during time spent in their winter environment would have been metabolized by the time they reached the breeding area. Loons typically return to breeding lakes within a day or two after ice out (Evers et al. 2010). Because the 2014 winter was exceptionally mild and ice out was 3 weeks earlier than normal (R. Espie, personal observation, 2014), loons likely returned to the breeding lakes in early to mid-May. This early arrival would have given the male loon on Mistohay Lake two to three weeks to eliminate any PAHs it acquired during its migration. Therefore, we feel that this individual was likely exposed to PAHs on its breeding lake. Also, elevated concentrations of PAHs were found in the scapular feathers of two of the four loons (50%) sampled in 2015. This indicates that these loons were exposed to PAHs in their wintering areas. Anthracene was observed in loon blood and phenanthrene was observed in feather tissue (Table 2). Both are lightweight, airborne-dispersed PAHs that persist for a long time in the environment. Because they are global pollutants it is difficult to identify their source, but oil sand operations west of the park produce PAHs and prevailing winds could deposit them in this region.

Hematocrit, glucose, total protein, and white blood cells fell within the normal range (Haefele et al. 2005) for loons (Table 3). All loons tested negative for avian influenza. Of the four loons assessed for blood chemistry, two (those breeding on Lac des Isles and Little Raspberry Lake) had no detectable feather PAH concentrations, and two (those breeding on Mistohay Lake and Mustus Lake) had high feather PAH concentrations, making an investigation of the physiological health of the birds with high PAH concentrations possible. One could posit that if oil exposure was high enough to cause tissue or organ damage then these loon individuals might also have elevated AST, ALT, LDH, and GGT levels compared with those individuals not exposed to PAHs. The results, however, were the reverse of what we expected (Table 3). Loons with no or low blood or feather PAH concentrations had high AST and ALA levels, whereas loons with high PAH concentrations had low AST and ALA levels. Given our small sample size, many other factors that we did not measure as part of our study could have brought about this result (e.g., stress, other contaminants, etc.). Baseline blood parameters are important references for assessing and monitoring population health and for understanding future population trends. As loons from this region of Saskatchewan winter in different ocean basins, there is the potential for the transmission of avian diseases from one basin to the other (Tracey et al. 2004). Thus, such baseline data are extremely valuable for monitoring the health of avian populations across the continent. More baseline data from loon populations across this region would be useful to obtain a broader understanding of overall loon health and exposure to environmental contaminants.

Collectively, these data suggest that loons in Meadow Lake Provincial Park are not at risk for Hg contamination; however, some individuals are exposed to PAHs in both their wintering and breeding areas. What effect, if any, these PAH concentrations have on loon fitness remains unclear. However, elevated blood PAH concentrations lower both body mass (body condition) and hematocrit levels (aerobic capacity) in common loons (Paruk et al. 2016), both of which are key factors for their survival and future reproductive success because they are long-distance migrants (Kenow et al. 2002; Paruk et al. 2014a, 2014b). Chronic exposure to environmental contaminants such as PAHs decreases fitness and survival (Iverson and Esler 2010). It is unclear what demographic or population level effects PAH exposure have on breeding loons in Meadow Lake Provincial Park, but the preliminary data suggest that it may warrant further monitoring.