Organohalogen contaminants and Blood plasma clinical-chemical parameters in three colonies of North Atlantic Great skua (Stercorarius skua).

The present study compares blood plasma clinical-chemical parameters (BCCPs) in birds from three geographically distinct North Atlantic Great skua (Stercorarius skua) colonies. Birds from these sites bioaccumulate different POP (persistent organic pollutant) concentrations and that enabled us to compare Great skua BCCPs in different exposure scenarios. Persistent organic pollutants (organochlorines: PCB, DDT, chlordanes, HCB, HCH, mirex and brominated flame retardants: PBDEs) and nineteen BCCPs were analysed in 114 adult Great skuas sampled during summer 2009 in North Atlantic colonies at Bjørnøya (n=42), Iceland (n=57) and Shetland (n=15). Specimens from Bjørnøya had the highest blood plasma concentrations of all contaminant groups followed by Iceland and Shetland birds, respectively (ANOVA: p<0.05). Most of the 19 BCCP parameters followed the pattern of colony differences found for contaminants, with Bjørnøya having the highest concentrations. However seven BCCPs, the three liver enzymes ALKP, ALAT and GGT as well as bile acids, cholesterol, sodium and potassium, did not differ between colonies (ANOVA: p>0.05). Therefore correlation analyses of these seven BCCPs vs. POPs were done on the combined colony data while the analyses of the remaining 12 BCCPs were carried out for each colony separately. The analyses of combined colony data showed that the blood plasma concentration of liver enzymes ALAT and GGT increased with increasing concentrations of ΣPBDE and ΣHCH, HCB and ΣCHL, respectively (all Pearson's p<0.05). In Great skuas from Shetland, the important osmotic transport protein albumin increased with increasing concentrations of ΣPCB and ΣDDT, while total blood plasma protein increased with ΣPCB, ΣDDT, ΣHCH and HCB concentrations (all Pearson's p<0.05). In both Bjørnøya and Iceland skuas, blood plasma pancreatic enzyme amylase decreased with increasing ΣHCH concentrations while the erythrocyte waste product total bilirubin in blood plasma increased with increasing ΣHCH and ΣPBDE concentrations in Iceland Great skuas (all Pearson's p<0.05). In Bjørnøya birds, blood plasma urea from protein metabolism (reflects kidney function) increased with increasing ΣPBDE concentrations (Pearson's p<0.05). Furthermore, a redundancy analysis showed that 10.6% of the variations in BCCPs could be explained by the variations in POP concentrations. Based on these results we suggest that liver and renal functions could be negatively affected by different POP compounds. It is, however, uncertain if the colony BCCP differences and their relationship to POP concentrations reflect health effects that could have an overall impact on the populations via reduced survival and reproduction parameters.