Ecotoxicological Effects of Four Commonly Used Organic Solvents on the Scleractinian Coral Montipora digitata

Abstract

Organic solvents are often used in aquatic toxicity tests to facilitate the testing of hydrophobic or poorly water-soluble substances such as ultraviolet (UV) filters, pesticides, or polycyclic aromatic hydrocarbons (PAHs). Knowledge of intrinsic effects (i.e., measured as standardized and non-standardized endpoints) of such carrier solvents in non-standardized organisms (i.e., corals), is critical to regulatory processes. Therefore, we exposed the reef-building coral Montipora digitata to the most commonly used carrier solvents ethanol, methanol, dimethyl sulfoxide, and dimethylformamide in the range of 10–100 µL L−1 for 16 days. The effects on mortality, photobiological, morphological, and oxidative stress markers were evaluated. In our study, all solvents resulted in significant morphological and/or oxidative stress responses, but not in mortality. Moreover, ethanol led to a rapid increase in turbidity, thus questioning its suitability as a carrier solvent in aquatic studies in general. Based on our observations, we could rank the solvent effects as follows: dimethylformamide < dimethyl sulfoxide ≈ methanol ≤ ethanol, with dimethylformamide showing the least and ethanol the most pronounced effects. We conclude that the use of solvents in toxicity studies with corals, particularly by examining non-standardized (e.g., morphological, physiological) endpoints, should be taken with caution and requires further elaboration.

Acute Toxicity Assays with Adult Coral Fragments: A Method for Standardization

“…Supplementary Materials S1.3—Figure S2 ) at DMF concentrations as low as 17.48 mg L −1 (nominal). In another study, the use of carrier solvents (e.g., DMF) in prolonged toxicity tests (16 days) led to sub-lethal effects (i.e., morphological variations) on M. digitata at concentrations of 100 mg L −1 (100 µL L −1 ) [ 50 ]. These authors collected evidence that the use of such additives leads to cumulative or confounding effects with the tested substance and that they need to be handled with caution.…”

The proliferation of antibiotic resistance genes (ARGs) and microbial communities in industrial wastewater treatment plant treating N,N-dimethylformamide (DMF) by AAO process

“…It has been widely used in diverse chemical, pharma industries because of its excellent miscibility with most organic liquids and water. As one of the components of industrial wastewater, DMF may enter the water body through sewage discharge, and have toxic effects on aquatic organisms, resulting in changes in the ecological structure and function of aquatic communities [ 7 ]. The presence of DMF may inhibit the growth and activity of soil microorganisms and destroy the function and stability of soil ecosystem [ 8 ].…”