Chronic Ingestion of Coal Fly-Ash Contaminated Prey and Its Effects on Health and Immune Parameters in Juvenile American Alligators (Alligator mississippiensis)

Abstract

Coal-burning power plants supply approximately 37 % of the electricity in the United States. However, incomplete combustion produces ash wastes enriched with toxic trace elements that have historically been disposed of in aquatic basins. Organisms inhabiting such habitats may accumulate these trace elements; however, studies investigating the effects on biota have been primarily restricted to shorter-lived, lower-trophic organisms. The American alligator (Alligator mississippiensis), a long-lived, top-trophic carnivore, has been observed inhabiting these basins, yet the health or immune effects of chronic exposure and possible accumulation remains unknown. In this study, we investigated how chronic dietary ingestion of prey contaminated with coal combustion wastes (CCWs) for 25 months, and subsequent accumulation of trace elements present in CCWs, affected juvenile alligator immune function and health. Alligators were assigned to one of four dietary-treatment groups including controls and those fed prey contaminated with CCWs for one, two, or three times a week. However, no effect of Dietary Treatment (p > 0.05) was observed on any immune parameter or hematological or plasma analyte we tested. Our results suggest that neither exposure to nor accumulation of low doses of CCWs had a negative effect on certain aspects of the immune and hematological system. However, future studies are required to elucidate this further.

Accumulation of coal combustion residues and their immunological effects in the yellow-bellied slider (Trachemys scripta scripta)

“…Furthermore, PHA swelling response in T. s. scripta was not correlated with any claw trace element concentrations. Similar to our results, Finger et al (2016) found that significant accumulation of trace elements present in CCRs had no effect on PHA swelling response in American alligators (Alligator mississippiensis). However, adult common eiders (Somateria mollissima) exposed to Se, a trace element found in high concentrations in coal ash, had weaker PHA responses relative to control birds (Franson et al 2007).…”

Relação entre elementos traço, resposta imune inata e níveis hormonais de anuros da espécie Rhinella diptycha

“…However, toads from the less contaminated site presented a greater edema intensity in response to a PHA injection, indicating that environmental contamination may impact the intensity of cellular immune response. Similar to our results, other studies showed that individuals living in contaminated sites or administrated with trace elements also respond to PHA injection but did not find correlation of trace elements accumulated in blood, kidney, and liver with swelling intensity (Beck et al, 2014;Finger et al, 2016). Our results together are pointing out that environmental contamination is driving physiological and morphological differences among the areas, with toads from the less contaminated site having better immunity.…”

“…Regarding immunity, toads from the three sites presented a similar general response pattern with a reduction of BKA in response to an acute stressor and an edema in response to a PHA injection. Similar results were found in studies with birds (Tachycineta bicolor and Somateria mollissima borealis), alligators (Alligator mississippiensis) and tortoises (Kinosternon subrubrum) comparing contaminated by trace elements and reference sites (Beck et al, 2014;Cochran et al, 2018;Finger et al, 2016;Wayland et al, 2002). This could indicate that contamination by trace elements do not interfere strongly in the ability of those animals to mount an immune response against foreign pathogens.…”

Snake scales record environmental metal(loid) contamination

“…Long-lived taxa such as turtles and crocodilians are particularly suitable bioindicators due to their longevity and affiliation with water (Buah-Kwofie et al 2018;Rowe 2008;Slimani et al 2018); however, the use of high trophic tier snakes is becoming increasingly common (Haskins et al 2019;Hopkins et al 2004;Lettoof et al 2020b;Liu et al 2019;Schwabenlander et al 2019). Reptiles respond to contaminant exposure differently to other taxa such as birds and mammals in several ways: they can ingest and accumulate high concentrations of contaminants that would be fatal to other taxa (Hopkins et al 2005;Weir et al 2015); they are generally more resistant to the toxicological effects of contaminants (Chin et al 2013;Finger et al 2016;Mauldin et al 2019); and their slower energy expenditure results in longer contaminant depuration times (Linder et al 2010;Rueda et al 2016).…”