Effects of white-tailed eagle (Haliaeetus albicilla) nestling diet on mercury exposure dynamics in Kopački rit Nature Park, Croatia

TY - JOUR

T1 - Effects of white-tailed eagle (Haliaeetus albicilla) nestling diet on mercury exposure dynamics in Kopački rit Nature Park, Croatia

AU - Bjedov, Dora

AU - Mikuska, Alma

AU - Begović, Lidija

AU - Bollinger, Eric

AU - Bustnes, Jan Ove

AU - Deme, Tamas

AU - Mikuška, Tibor

AU - Morocz, Attila

AU - Schulz, Ralf

AU - Søndergaard, Jens

AU - Eulaers, Igor

PY - 2023/11

Y1 - 2023/11

N2 - The present study assessed for the first time the magnitude and dietary ecological source of total mercury (THg) exposure in a southern population of white-tailed eagles (Haliaeetus albicilla), an apex predator species shown valuable for environmental biomonitoring. This population depends on the Kopački rit Nature Park – the most important breeding site. We assessed THg exposure, using nestling body feathers collected between 2014–2019 (n = 72), and potential dietary ecological sources, proxied by prey remains and stable isotope analysis. Results show THg concentrations vary significantly over the years, though not showing any time trend. Prey remains analysis shows nests with aquatic prey remains to exhibit higher THg concentrations (median: 7.57 μg g−1 dw; min – max: 6.00–13.16 μg g−1 dw) compared to those with terrestrial remains (median: 3.94 μg g−1 dw; min – max: 0.28–12.04 μg g−1 dw) or evidencing a mixed diet (median: 7.43 μg g−1 dw; min – max: 3.38–12.04 μg g−1 dw). Nests with a predominant aquatic diet show elevated lower δ13C and higher δ15N values, indicating agreement between both dietary approaches. The model selection reveals a combination of year and δ15N best explain the variability in feather THg concentrations. Complementing these predictors with a dietary descriptor based on prey remains results in a poorer model fit and lowered explanatory power, similar to sexing the nestlings. The observed body feather THg concentrations (median: 6.99 μg g−1 dw; min − max: 0.27 − 17.16 μg g−1 dw) exceeded putative biogeochemical background levels (5.00 μg g−1 dw) in 71% of the nestlings, though, did not seem to exceed a threshold at which detrimental physiological effects are expected (40 μg g−1 dw). Continued monitoring is warranted as the studied population is likely exposed to a larger cocktail of contaminants while resident-protected bird areas.

AB - The present study assessed for the first time the magnitude and dietary ecological source of total mercury (THg) exposure in a southern population of white-tailed eagles (Haliaeetus albicilla), an apex predator species shown valuable for environmental biomonitoring. This population depends on the Kopački rit Nature Park – the most important breeding site. We assessed THg exposure, using nestling body feathers collected between 2014–2019 (n = 72), and potential dietary ecological sources, proxied by prey remains and stable isotope analysis. Results show THg concentrations vary significantly over the years, though not showing any time trend. Prey remains analysis shows nests with aquatic prey remains to exhibit higher THg concentrations (median: 7.57 μg g−1 dw; min – max: 6.00–13.16 μg g−1 dw) compared to those with terrestrial remains (median: 3.94 μg g−1 dw; min – max: 0.28–12.04 μg g−1 dw) or evidencing a mixed diet (median: 7.43 μg g−1 dw; min – max: 3.38–12.04 μg g−1 dw). Nests with a predominant aquatic diet show elevated lower δ13C and higher δ15N values, indicating agreement between both dietary approaches. The model selection reveals a combination of year and δ15N best explain the variability in feather THg concentrations. Complementing these predictors with a dietary descriptor based on prey remains results in a poorer model fit and lowered explanatory power, similar to sexing the nestlings. The observed body feather THg concentrations (median: 6.99 μg g−1 dw; min − max: 0.27 − 17.16 μg g−1 dw) exceeded putative biogeochemical background levels (5.00 μg g−1 dw) in 71% of the nestlings, though, did not seem to exceed a threshold at which detrimental physiological effects are expected (40 μg g−1 dw). Continued monitoring is warranted as the studied population is likely exposed to a larger cocktail of contaminants while resident-protected bird areas.

KW - Apex predator

KW - Biomonitoring

KW - Prey remains

KW - Risk assessment

KW - Stable isotope analysis

UR - https://www.scopus.com/pages/publications/85168826953

U2 - 10.1016/j.envpol.2023.122377

DO - 10.1016/j.envpol.2023.122377

M3 - Journal article

C2 - 37586682

AN - SCOPUS:85168826953

SN - 0269-7491

VL - 336

JO - Environmental Pollution

JF - Environmental Pollution

M1 - 122377

ER -