Persistent Organic Pollutants (POPs) in the Puget Sound Ecosystem: An evaluation of POPs in fecal samples of Southern Resident killer whales

The Puget Sound ecosystem of Washington State has been riddled with human impacts. Exposure to persistent organic pollutants (POPs) is listed as a primary risk factor for the endangered Southern Resident killer whale (SRKWs, Orcinus orca) population that resides in these waters. The objective of this study is to obtain real-time measures of POP (PBDEs, PCBs, and DDTs) levels in SRKW scat (fecal) samples to quantify variations in toxicant levels by pod, age, sex, reproductive status, and birth order, as well as prey availability and year. Samples were collected using detection dogs that ride on the bow of a boat and use scent to locate fresh scat on the water’s surface. Using this non-invasive method we collected 267 samples over 4 years (2010-2013) across our 5-month study period. In our validation study using samples from 14 individual whales, gas chromatography/mass spectrometry was used to quantify contaminant levels, reproductive and thyroid hormones measurements were measured by radioimmunoassay, and species/individual was confirmed by DNA analysis. Significant correlations were apparent between toxicant measurements in scat and previously analyzed blubber-biopsy samples from the same whale (n=7 unique pairs; ∑PCBs, r=0.75, p=0.05; ∑PBDEs, r=0.76, p=0.05; ∑DDTs, r=0.92, p \u3c 0.01). Consistent with blubber biopsy measurements, the toxicant profiles in scat samples demonstrate significantly higher ∑DDT/∑PCB ratios in K and L pods, known to forage off the California coast, compared to J pod (p=0.02 and 0.02, respectively), and significantly lower (p \u3c 0.05) levels of ∑PCB, ∑PBDE, and ∑DDT were detected in reproductive age females compared to males and post-reproductive females, adjusted for pod. These validated measures will be applied to all samples to investigate temporal patterns and variations in toxicant levels relative to population demographics, hormones measures, and environmental factors. Results are forthcoming and will be presented at the conference