Impacts of Climate and Feeding Conditions on the Annual Accumulation (1986–2009) of Persistent Organic Pollutants in a Terrestrial Raptor

Abstract

The relationships between climate variability, feeding conditions, and the annual accumulation of polychlorinated biphenyls (PCB), 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p'-DDE) and polybrominated diphenyl ethers (PBDE) in eggs (n = 168) of tawny owls (Strix aluco) were assessed over a 24-year period (1986-2009) in Central Norway. Winter climate variables included the North Atlantic Oscillation (NAO) and snow conditions, whereas feeding conditions were assessed using vole abundance. The concentrations of all compounds declined between 79% (p,p'-DDE) and 86% (PBDE) over the time period. For PCB and p,p'-DDE, the accumulation was positively associated with snow depth, and negatively associated with NAO (i.e., high accumulation in cold and dry winters) when vole abundance was low, suggesting trade-offs between winter severity and feeding conditions. That is, females mobilize more body fat reserves in cold winters when feeding conditions are poor, which results in increased circulating contaminant concentrations and maternal transfer to the eggs. Owls may also have been forced to feed on prey with higher contaminant loads due to restricted prey availability. For the recently banned PBDEs, the accumulation was high when NAO was low, while snow depth was positively associated with PBDE accumulation only when feeding conditions were good. This suggests somewhat different dynamics of PBDE in the environment or in the owls, compared to PCB and p,p'-DDE. However, climate and feeding conditions explained as much of the annual variation in concentrations of all POPs, as the overall decreasing trend over the 24 years. Hence, such factors should be considered in monitoring programs for POPs. Moreover, to better understand the mechanisms of climate effects on POP accumulation, future studies should measure pollutants in different components of the food chain.

Perfluoroalkyl substance concentrations in a terrestrial raptor: Relationships to environmental conditions and individual traits

“…All information regarding the chemical analyses of PFASs (i.e., C 6 –C 8 , C 10 PFSAs [perfluorohexane sulfonate, perfluoroheptane sulfonic acid, PFOS, perfluorodecane sulfonate], C 8 –C 14 PFCAs [perfluoro‐octanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorotetradecanoic acid], and perfluoro‐octane sulfonate) in tawny owl eggs collected between 1986 and 2009 can be found in Ahrens et al . The chemical analysis of the lipid‐soluble persistent organic pollutants (i.e., polychlorinated biphenyls [PCBs], dichlorodiphenyldichloroethylene [DDE], and polybrominated diphenyl ethers) is described in Bustnes et al .…”

“…Second, such increased input could, however, be facilitated or offset by local conditions. For example, precipitation or snow may make the PFASs more or less accessible to different species in the food chain , and temperature may influence chemical processes (possibly biotransformation) or the behavior of different prey. Third, since most PFASs are biomagnifying , the intake by the owls may vary depending on the trophic position of the prey; that is, when owls are feeding on herbivorous voles, they will be expected to have a lower intake of PFAS than when feeding on insectivorous birds .…”

“…Finally, PFASs are environmentally persistent, and accumulation in individuals may occur over years, suggesting that older females will lay eggs with higher content than young ones. Moreover, since PFASs are also associated with plasma lipid levels , the excretion of such compounds into the eggs may depend on female lipid dynamics and thereby body condition . Furthermore, since tawny owls lay as many as 6 eggs , the contaminant load will be divided among several eggs and each egg may contain less PFAS, predicting a negative relationship with clutch size.…”

Combined and interactive effects of global climate change and toxicants on populations and communities

“…In contrast, tawny owls ( Strix aluco ) accumulated more PCB in years with colder winters than in years with warmer winters. One of the proposed explanations was that in strict winters, availability of the preferred prey (voles) was restricted, and the owls may have been forced to feed on alternative prey (passerine birds) with higher contaminant loads 38. Clearly, more knowledge is needed on the impacts of GCC on trophic interactions for better prediction of toxicant exposure and bioavailability through food webs 39, 40.…”

“…Studies of regular large-scale climatic forcing, such as the North Atlantic Oscillation and the El Niño–Southern Oscillation, have given much insight into climatic influences on ecological processes (reviewed in Stenseth et al 89). Such short-term for long-term approaches would also bring more realism into field studies of toxicant effects under climate change 38. Nevertheless, the time frame of ecological responses to these climatic phenomena would still be short compared with the long-term climatic trends.…”