Abstract
Here we review contaminant exposure and related health effects in six selected Baltic key species. Sentinel species included are common eider, white-tailed eagle, harbour porpoise, harbour seal, ringed seal and grey seal. The review represents the first attempt of summarizing available information and baseline data for these biomonitoring key species exposed to industrial hazardous substances focusing on anthropogenic persistent organic pollutants (POPs). There was only limited information available for white-tailed eagles and common eider while extensive information exist on POP exposure and health effects in the four marine mammal species. Here we report organ-tissue endpoints (pathologies) and multiple biomarkers used to evaluate health and exposure of key species to POPs, respectively, over the past several decades during which episodes of significant population declines have been reported. Our review shows that POP exposure affects the reproductive system and survival through immune suppression and endocrine disruption, which have led to population-level effects on seals and white-tailed eagles in the Baltic. It is notable that many legacy contaminants, which have been banned for decades, still appear to affect Baltic wildlife. With respect to common eiders, changes in food composition, quality and contaminant exposure seem to have population effects which need to be investigated further, especially during the incubation period where the birds fast. Since new industrial contaminants continuously leak into the environment, we recommend continued monitoring of them in sentinel species in the Baltic, identifying possible effects linked to climate change, and modelling of population level effects of contaminants and climate change.
Highlights
Determining the health status of wildlife including marine mammals is difficult as they are rarely observed and handled (Dietz et al, 2019; Letcher et al, 2010)
Since new industrial contaminants continuously leak into the environment, we recommend continued monitoring of them in sentinel species in the Baltic, identifying possible effects linked to climate change, and modelling of population level effects of contaminants and climate change
A significant decrease in xenobiotic markers Aryl hydrocarbon receptor (AHR) and Aryl hydrocarbon receptor nuclear translocator (ARNT) transcription was found in grey seal pups after weaning rehabilitation due to persistent organic pollutants (POPs) exposure during lactation reinforced by maternal fasting and adipose tissue mobilization (Lehnert et al 2014)
Summary
Determining the health status of wildlife including marine mammals is difficult as they are rarely observed and handled (Dietz et al, 2019; Letcher et al, 2010). To manage and conserve wildlife populations, it is crucial to quantify how pollution measured at the individual level propagates to population-level effects through impacts on mortality and reproduction, and effects on fertility, energy allocation, immune and endocrine functioning (Harding and Härkönen, 1999; Sundqvist et al, 2012; Harding et al, 2015) This requires a combination of in vitro doseresponse studies as well as in vivo studies of key species in the Baltic as reference populations from pristine areas such as the Arctic when possible. Information about health effects in the seal species was comprehensive while fewer investigations are reported on harbour porpoise, white-tailed eagles and common eiders that spend most of their time in the Baltic despite migration out of the area is happening after end breeding season (Kjellén and Roos, 2000; Swennen et al, 1989) These species were selected as they represent sentinel high trophic indicator species in the Baltic regions that for decades have been used to biomonitor the environment. The effects from other stressors such as infectious diseases on Baltic sentinel species is reported elsewhere in this virtual special issue (VSI) of Environment International
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