Mercury concentrations in blood and feathers of nestling Bald Eagles in coastal and inland Virginia

Abstract

Background: Mercury (Hg) and methylmercury are widely considered significant issues for wildlife, and in particular, piscivorous birds due to their widespread availability and neurotoxic properties. Whereas a substantial number of studies of Hg contamination of Bald Eagles (Haliaeetus leucocephalus) have been conducted throughout the east coast of the United States, little has been done that directly addresses Hg contamination in Bald Eagles in Virginia, particularly the inland population. Methods: We collected blood and feather samples from nestling Bald Eagles in the coastal plain, piedmont, and western regions of Virginia in an effort to determine which areas of the state were more likely to contain populations showing evidence of Hg toxicity. We analyzed the samples for total Hg using a Milestone DMA-80. Results: Samples collected from individuals located in the coastal region exhibited low concentrations of Hg compared to those further inland located on freshwater rivers and reservoirs. Samples collected from the inland population exhibited levels in some areas that are approaching what may be considered to be sub-lethal to avian health (blood: mean 0.324 mg/kg, SE = 0.13, range = 0.06-0.97 mg/kg; feather: mean = 8.433 mg/kg, SE = 0.3, range = 3.811-21.14 mg/kg). Conclusions: Even after accounting for known point-sources of Hg, the inland eagle population in Virginia is susceptible to concentrations of Hg that are significantly higher than their coastal counterparts. Moreover, several locations besides those currently known to be impacted by point-sources are exhibiting concentrations that are approaching a sub-lethal level.

Birds and plastic pollution: recent advances

“…These species could be used as bioindicators to evaluate the plastic pollution burden in different environments because they have been well studied in the past two decades. In addition, as long-lifespan species (e.g., albatrosses, shearwaters, and vultures) can breed over many decades (Moore 2008 ), they could be used to evaluate the potential toxicological effects of chronic plastic exposure on both individual survival and reproductive output (Kramar et al 2019 ; Marín-Gómez et al 2020 ; Sánchez et al 2020 ). Furthermore, these species could be used to evaluate the effects of food contaminated with plastic debris and the intergenerational transfer of MPs through allofeeding of offsprings (Sánchez et al 2020 ), as observed in the Cory’s Shearwater ( Calonectris diomedea ) fledglings (Rodríguez et al 2012 ), Providence Petrel ( Pterodroma solandri ) (Bester et al 2010 ), Black-footed Albatross ( Phoebastria nigripes ) (Rapp et al 2017 ), Laysan Albatross ( P. immutabilis ) (Young et al 2009 ), Short-tailed Shearwater (Carey 2011 ), Wedge-tailed Shearwater ( A. pacifica ) (Verlis et al 2013 ), Flesh-footed Shearwater (Lavers et al 2014 ), and other petrels (Rapp et al 2017 ).…”

Does melanin-based plumage coloration reflect health status of free-living birds in urban environments?

“…This procedure is the best method used in most bird species, because many species do not have other blood vessels large enough for venipuncture (Stevens and Ridgway 1966). In recent studies, the methods of blood collection are not very detailed (Kramar et al 2019) even if this is a common procedures. In the following details, all the steps are listed to ensure optimal reproducibility of the work.…”