Food resources influence levels of persistent organic pollutants and stable isotopes of carbon and nitrogen in tissues of Arctic foxes (Vulpes lagopus) from the Pribilof Islands, Alaska

Figures & data

Table 1. Summary data and ANOVA results for Pribilof foxes. Geometric means of fat POP concentrations (ng/g, lipid wt), and arithmetic means of lipids in fat with 95% CI, ANOVA F-statistics and p values for covariates (sex, age class, island, access to anthropogenic foods and body condition), by summed POP concentrations. Covariates for which there are significant differences (p < 0.05) are in boldface. Tukey’s HSD test was used to determine post-hoc pairwise significant differences in POP mean values (by analyte class) within covariate groups. Single and double asterisks denote statistically significant differences between levels of a parameter (p < 0.05).

		Lipid (%)			∑PCBs^a			∑CHLs^b			∑HCHs^c			∑DDTs^d			HCB			∑PBDEs^e
	n	mean	95% CI	F, p	mean	95% CI	F, p	mean	95% CI	F, p	mean	95% CI	F, p	mean	95% CI	F, p	mean	95% CI	F, p	n	mean	95% CI
Female	27	71	67–75	1.3, 0.26	1514*	1015–2257	6.0, 0.02	1318*	907–1915	6.0, 0.02	295*	207–421	8.1, <0.01	78*	49–123	6.6,0.01	13	8–23	0.4, 0.52	6	29	21–39
Male	23	66	57–74		3388*	2038–5632		2818*	1728–4597		646*	431–968		178*	118–269		10	6–19		10	60	36–101
Adult	35	67	61–73	0.8, 0.37	2291	1601–3279	0.3, 0.58	1995	1352–2944	0.8, 0.37	427	307–592	0.1, 0.76	110	75–161	<0.1, 0.99	11	6–18	0.6, 0.45	13	47	29–74
Nonadult	16	72	66–77		1862	894–3877		1479	851–2571		380	211–684		110	57–211		15	9–24		3	41	29–57
Adult F	19	70	65–75	1.4, 0.25	1738	1173–2576	1.7, 0.19	1514	990–2314	2.3, 0.11	339	229–502	1.5, 0.24	85	49–149	1.3, 0.28	13	6–27	0.7, 0.49	5	28	20–39
Adult M	15	63	51–74		3548	1958–6428		3162	1647–6073		603	357–1018		166	103–268		8	4–18		8	66	35–125
Juveniles	16	72	66–77		1862	894–3877		1479	851–2571		380	211–684		110	57–211		15	9–24		3	41	29–57
St. George	13	70	61–79	0.1, 0.71	1380	985–1935	2.3, 0.13	1000*	731–1367	5.3, 0.03	302	250–364	1.4, 0.24	126	84–188	0.2, 0.64	33*	15–73	11.2, <0.01	10	36	28–48
St. Paul	38	68	63–73		2455	1605–3753		2239*	1519–3300		457	315–664		105	68–160		9.0*	6–12		6	68	28–161
Access – high	19	69	62–75	0.8, 0.44	1738	924–3268	1.6, 0.21	1585	935–2687	1.7, 0.20	331	195–561	1.4, 0.27	46*^,**	26–79	11.3, <0.01	11	7–17	0.2, 0.79	2	33	19–57
Access – possible	15	73	65–80		1698	1005–2869		1380	897–2124		372	247–559		186**	117–297		10	5–23		4	47	22–98
Access – low	17	65	57–74		3236	1956–5354		2754	1476–5140		562	344–920		182*	123–270		14	7–32		10	49	28–84
Body condition – excellent	12	76*	68–83	3.9, 0.01	1349	770–2362	0.9, 0.45	1288	726–2285	1.3, 0.28	339	174–659	0.2, 0.91	120	59–246	0.4, 0.75	16	7–35	1.3, 0.29	4	51	20–129
Body condition – very good	18	73	69–77		2291	1529–3432		1820	1215–2726		407	293–567		135	84–218		14	8–25		7	39	28–54
Body condition – good	15	63	54–72		2399	1112–5176		1738	926–3260		437	244–782		89	46–173		12	6–25		2	35	33–37
Body condition – fair	6	55*	38–72		3236	891–11752		3981	981–16148		479	147–1556		85	27–267		4	2–13		3	68	12–368

^a∑PCBs is the sum of congeners 17, 18, 28, 31, 33, 44, 49, 52, 66, 70, 74, 82, 87, 95, 99, 101/90, 105, 110, 118, 128, 138/163/164, 149, 151, 153/132, 156, 158, 170, 171, 177, 180, 183, 187, 191, 194, 195, 199, 205, 206, 208 and 209 (Ballschmiter et al. 1992). ^b∑CHLs is the sum of cis-chlordane, trans-chlordane, cis-nonachlor, trans-nonachlor, nonachlor III, heptachlor, heptachlor epoxide and oxychlordane. ^c∑HCHs is the sum of α-HCH, β-HCH and γ-HCH (lindane). ^d∑DDTs is the sum of o,p’-DDD, p,p’-DDD, o,p’-DDE, p,p’-DDE, o,p’-DDT and p,p’-DDT. ^e∑PBDEs is the sum of BDE congeners 28, 47, 49, 66, 85, 99, 100, 153, 154, 155 and 183 (labelled according to the same scheme as the Ballschmiter congener designations for chlorinated biphenyls). PBDEs were only determined in a subset (n = 16) of samples.

Table 2. Summary data and ANOVA results for Pribilof foxes. Arithmetic means of stable isotope values of carbon and nitrogen (‰) in muscle with 95% confidence intervals (CI), and ANOVA F-statistics and p values for covariates (sex, age class, island, access to anthropogenic foods and body condition), by stable isotope values. Covariates for which there are significant differences (p < 0.05) are in boldface. Tukey’s HSD test was used to determine post-hoc pairwise significant differences in mean values within covariate groups. Single and double asterisks denote statistically significant differences between levels of a parameter (p < 0.05).

		δ^13C (aq)^a			δ^15N
	n	mean	95% CI	F, p	mean	95% CI	F, p
Female	22	-19	-19.5 – -18.5	<0.1, 0.91	14.8*	13.9–15.7	6.1, 0.02
Male	17	-19	-19.7 – -18.4		16.3*	15.6–17.1
Adult	26	-18.9	-19.4 – -18.5	0.5, 0.48	15.7	14.9–16.4	0.8, 0.37
Nonadult	13	-19.1	-19.8 – -18.5		15.1	13.9–16.2
Adult F	15	-19	-19.5 – -18.5	0.3, 0.73	15.2	14.0–16.3	1.6, 0.21
Adult M	11	-18.8	-19.7 – -18.0		16.4	15.5–17.3
Juveniles	13	-19.1	-19.8 – -18.5		15.1	13.9–16.2
St. George	13	-19.3	-20.1 – -18.5	1.1, 0.31	16.1	15.0–17.1	1.8, 0.18
St. Paul	26	-18.8	-19.3 – -18.4		15.2	14.4–15.9
Access: high	16	-18.7**	-19.0 – -18.4	4.8, 0.01	14.2*	13.6–14.8	8.5, <0.01
Access: possible	8	-19.8*,**	-20.9 – -18.7		15.6	13.9–17.3
Access, low	15	-18.9*	-19.5 – -18.2		16.8*	15.9–17.6
Body condition: excellent	8	-19.4	-20.1 – -18.8	2.3, 0.10	15.8	14.3–17.2	2.6, 0.07
Body condition: very good	13	-18.6	-19.0 – -18.2		16.2	15.3–17.0
Body condition: good	14	-19.3	-20.1 – -18.4		14.4	13.4–15.4
Body condition: fair	4	-18.4	-19.4 – -17.3		16.5	14.1–19.0

^a Carbon stable isotope values were normalized for lipid content according to the method of Post et al. (2007) for aquatic organisms.

Table 3. PCA rotated component-loading weights for POPs contaminant classes and stable isotopes in Pribilof foxes (n = 39). Only weights > 0.5 were reported.

	Factor 1	Factor 2	Factor 3	Factor 4
% variance	47.7	16.9	15.0	13.7
eigenvalue	3.3	1.2	1.1	1.0
∑PCBs	0.58
∑CHLs	0.58
∑HCHs	0.57
∑DDTs				0.64
HCB			0.95
δ^13C^a		0.90
δ^15N				0.77

^a Carbon stable isotope values normalized for lipid content according to the method of Post et al. (2007) for aquatic organisms.

Figure 1. Proportions of PCB congeners by homolog group (chlorination level) in adult male, adult female and juvenile/pup Pribilof foxes from St. Paul and St. George islands. Tri-and tetra-chlorinated congeners made an insignificant contribution (<2%) to the totals and are not shown.

Figure 2. Nitrogen (δ¹⁵N) vs. carbon (δ¹³C) stable isotope values (‰) in Pribilof foxes by sex and island. Error bars are standard error. For both islands combined, males had significantly higher δ¹⁵N values than females (16.3‰ vs. 14.8‰; p = 0.02).

Table 4. Full GLM parameters and coefficients for PCA Factors 1 to 4 for POPs and stable isotopes in Pribilof foxes (n = 39). Age class (adult vs. juvenile/pup), sex, island and access to human foods were included as potential covariates. Covariates for which there are significant differences (p < 0.05) are in boldface.

			Standard
	Model	Estimate	error	p value
Factor 1	Intercept	−0.92	0.58	0.125
	Sex (male)	1.53	0.50	0.004
	Island (St. Paul)	1.88	0.59	0.003
	Access (high vs. low)	−1.47	0.61	0.023
	Access (possible vs. low)	−0.65	0.72	0.378
	Age class (adult vs. nonadult)	−0.79	0.57	0.171
Factor 2	Intercept	−0.27	0.35	0.939
	Sex (male)	−0.14	0.30	0.640
	Island (St. Paul)	−0.32	0.35	0.368
	Access (high vs. low)	1.18	0.37	0.003
	Access (possible vs. low)	−0.74	0.43	0.096
	Age class (adult vs. nonadult)	−0.10	0.34	0.771
Factor 3	Intercept	0.97	0.38	0.015
	Sex (male)	−0.26	0.32	0.424
	Island (St. Paul)	−1.07	0.38	0.007
	Access (high vs. low)	−0.21	0.40	0.596
	Access (possible vs. low)	−0.21	0.47	0.661
	Age class (adult vs. nonadult)	−0.032	0.37	0.931
Factor 4	Intercept	0.78	0.37	0.044
	Sex (male)	−0.11	0.32	0.736
	Island (St. Paul)	−0.73	0.37	0.060
	Access (high vs. low)	−0.5	0.40	0.212
	Access (possible vs. low)	−0.68	0.46	0.150
	Age class (adult vs. nonadult)	−0.29	0.36	0.424

Ballschmiter K., Bacher R., Mennel A., Fischer R., Riehle U. & Swerev M. 1992. The determination of chlorinated biphenyls, chlorinated dibenzodioxins, and chlorinated bibenzofurans by GC-MS. Journal of High Resolution Chromatography 15, 261–270.

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Post D.M., Layman C.A., Arrington D.A., Takimoto G., Quattrochi J. & Montana C.G. 2007. Getting to the fat of the matter: models, methods and assumptions for dealing with lipids in stable isotope analyses. Oecologia 152, 179–189.

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