Interactions between phenanthrene exposure and historical chemical stress: Implications for fitness and ecological resilience of the sentinel species Daphnia magna

• Published in: The Science of the total environment Vol. 949; p. 174963
• Main Authors: Gigl, Florian, Abdullahi, Muhammad, Barnard, Marianne, Hollert, Henner, Orsini, Luisa
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-11-2024
• Subjects: Acute toxicity; Chronic toxicity; Fitness; PAHs; Waterflea; PAHs; Chronic toxicity; Waterflea; Acute toxicity; Fitness
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.174963

Polycyclic aromatic hydrocarbons (PAHs) arise from incomplete combustion of oil, coal, and gasoline, with lipophilic properties facilitating their widespread distribution and persistence. Due to their biochemical attributes, PAHs can accumulate in animal tissues, potentially causing mutagenic and carcinogenic effects. Since the industrial revolution, PAH concentrations in the environment have risen, with lakes showing levels from 0.159 to 33,090 μg/kg sediment. Despite acute toxicity studies showing adverse effects on freshwater organisms, the long-term impacts and synergistic interactions with other pollutants remain largely unexplored.
This study investigates the impact of phenanthrene (PHE), a prominent PAH found in aquatic environments, on Daphnia magna, a species of significant ecological importance in freshwater ecosystems globally, being both a sentinel species for chemical pollution and a keystone organism in freshwater aquatic ecosystems. Leveraging the dormancy of D. magna, which spans decades or even centuries, we exposed strains with diverse histories of chemical contaminant exposure to environmentally relevant concentrations of PHE. Initially, acute exposure experiments were conducted in accordance with OECD guidelines across 16 Daphnia strains, revealing substantial variation in acute toxic responses, with strains naïve to chemical pollutants showing the lowest toxicity. Utilizing the median effect concentration EC10 derived from acute exposures, we assessed the impacts of chronic PHE exposure on life history traits and ecological endpoints of the 16 strains. To elucidate how historical exposure to other environmental stressors may modulate the toxicity of PHE, temporal populations of D. magna resurrected from a lake with a well-documented century-spanning history of environmental impact were utilized. Our findings demonstrate that PHE exposure induces developmental failure, delays sexual maturation, and reduces adult size in Daphnia. Populations of Daphnia historically exposed to chemical stress exhibited significantly greater fitness impacts compared to naïve populations. This study provides crucial insights into the augmented effects of PAHs interacting with other environmental stressors.
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•Leveraging Daphnia dormancy, we assessed acute and chronic PHE toxicity in strains with varied contaminant exposure histories•PHE exposure induces developmental failure, delays sexual maturation, and reduces adult size in Daphnia•Populations of Daphnia with chemical exposure history had greater fitness impacts than naïve ones•We challenge the validity of current toxicity practice based on acute toxicity tested of single genotypes