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

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 some areas 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. ...,
Study system: The Daphnia genotypes used in this study were previously resurrected from the sedimentary archive of Lake Ring, a shallow mixed lake in Jutland, Denmark (55°57′51.83″N. 9°35′46.87″E) (Cuenca Cambronero, Marshall, et al., 2018). The lake was semi-pristine between the 1900s and 1950s (semi-pristine phase; SP); sewage inflow from a nearby town increased the lake’s trophic levels leading to eutrophication from the 1950s to the 1970s (eutrophic phase; EP). Sewage was diverted from the 1980s, when run-off from agricultural land surrounding the lake caused an increase in pesticides inflow (1980-1990; pesticide phase; PP). Land use declined in modern times when the lake started recovering (Recovery Phase; RP) (Cuenca Cambronero et al., 2018; Davidson et al., 2007; Eastwood et al., 2023). Four D. magna genotypes from each lake phase were used in this study for acute and chronic exposures. Before the experiments, Daphnia genotypes were acclimated at 20±1 °C, 16:8 hr light-dark phot..., , 1. Gigl_etal_chronic toxicity. Fitness-linked life history traits collected following exposure to phenanthrene (PHE). GenotypeID; replicate; lake phase; treatment; age at maturity; size at maturity; day of release and size of first and second brood; overall fecundity expresses as number of juveniles in first and second brood combined; and mortality are shown. If mortality occurred before sexual maturity, life history traits linked to later life stages were not recorded (‘null’). If a mortality event does not occur and the life history traits are not recorded (‘null’), the individual is classified as a male.
2. Gigl_etal_acute toxicity: GenotypeID; replicate; lake phase; treatment (Phenanthrene concentration); percentage of immobilized Daphnia after 24h and 48h are shown.

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