Salinity Alters Toxicity of Commonly Used Pesticides in a Model Euryhaline Fish Species (Menidia beryllina)

Abstract

Changing salinity in estuaries due to sea level rise and altered rainfall patterns, as a result of climate change, has the potential to influence the interactions of aquatic pollutants as well as to alter their toxicity. From a chemical property point of view, ionic concentration can increase the octanol–water partition coefficient and thus decrease the water solubility of a compound. Biologically, organism physiology and enzyme metabolism are also altered at different salinities with implications for drug metabolism and toxic effects. This highlights the need to understand the influence of salinity on pesticide toxicity when assessing risk to estuarine and marine fishes, particularly considering that climate change is predicted to alter salinity regimes globally and many risk assessments and regulatory decisions are made using freshwater studies. Therefore, we exposed the Inland Silverside (Menidia beryllina) at an early life stage to seven commonly used pesticides at two salinities relevant to estuarine waters (5 PSU and 15 PSU). Triadimefon was the only compound to show a statistically significant increase in toxicity at the 15 PSU LC50. However, all compounds showed a decrease in LC50 values at the higher salinity, and all but one showed a decrease in the LC10 value. Many organisms rely on estuaries as nurseries and increased toxicity at higher salinities may mean that organisms in critical life stages of development are at risk of experiencing adverse, toxic effects. The differences in toxicity demonstrated here have important implications for organisms living within estuarine and marine ecosystems in the Anthropocene as climate change alters estuarine salinity regimes globally.

Accounting for transgenerational effects of toxicant exposure in population models alters the predicted long-term population status

“…Bif, which is a commonly used insecticide and a member of the third most popular class of pesticides used globally (pyrethroids), is not designed to specifically interact with hormone receptors [ 27 , 36 ]. However, a number of studies demonstrate that Bif can act as both an estrogen receptor (ER) agonist and antagonist in fishes and in vitro , depending upon metabolic state and concentration [ 36 , 59–61 ].…”

“…Given that disrupted egg production, decreased hatching rates, or lowered quality of offspring all directly contribute to population fitness [ 24–26 ], the observed impact to silverside fecundity and thus fitness at environmentally relevant exposure levels (ng/l) in the above-described works calls for a better understanding of the longer-term implications. Furthermore, as a bioindicator species [ 21 , 27 ], measured impacts to the silverside can be extrapolated to fishes with similar life histories, exposure risks, and/or habitat usage. For these reasons, we used data acquired from earlier empirical work to parameterize a single-species population model to predict the impact of a single exposure to EDC representative of those detected in aquatic ecosystems globally, as well as to extrapolate to estimate cumulative effects from a more realistic continuous exposure scenario.…”

Natural and synthetic microfibers alter growth and behavior in early life stages of estuarine organisms

“…Microfiber exposures with mysids were initiated at seven days post fertilization (dpf) (n=9) under static renewal conditions for seven days. Menidia beryllina embryos were harvested from broodstock held at the OSU Hatfield Marine Science Center and placed into three acclimation aquaria of 5, 15, and 25 PSU salinities with filtered AFSW following modified methods from Middaugh et al (1987), as done in previous studies in the Brander lab (DeCourten et al, 2020;Hutton et al, 2021;Siddiqui et al, 2022). Larvae were placed into exposure vessels at 6 ± 1 days post fertilization (dpf) (n=6) and maintained under static renewal conditions for 96 h.…”

Norethindrone alters growth, sex differentiation and gene expression in marine medaka (Oryzias melastigma)

“…947 ng/g 33 . Due to the compound effect of salinity on the activity of pollutants, the experiments in freshwater fish may not be able to accurately assess the ecological risk of the NET in the ocean 34 . Marine medaka ( Oryzias melastigma ) is a small euryhaline fish, which is widely used in monitoring toxicity in aquatic environments 35–37 .…”

“…33 Due to the compound effect of salinity on the activity of pollutants, the experiments in freshwater fish may not be able to accurately assess the ecological risk of the NET in the ocean. 34 Marine medaka (Oryzias melastigma) is a small euryhaline fish, which is widely used in monitoring toxicity in aquatic environments. [35][36][37] In this study, long-term exposure to NET was used to evaluate the effect of NET on the growth, sexual differentiation, gonadal histology, and transcriptional expression of genes related to the HPG axis.…”