Cristina Morales-Reyes1, Thomas Wichard1
1Institute for Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Germany.
Unfortunately, pollution caused by mine drainage is more common than we think. Untreated copper wastes flowing directly into a bay resulted in massive mortality of fish and molluscs (Castilla and Nealler 1978). However, Ulva compressa was unmistakably a visible aquatic organism inhabiting the discharge site, suggesting tolerance to high copper concentrations (Vermeer and Castilla 1991). To date, this discovery has prompted copper studies in Ulva compressa (Moenne et al. 2020).
Chemical signals are important interaction mediators between organisms that significantly impact ecosystems. Ecologists and analytical chemists work closely to identify the specific molecules that regulate ecological interactions, and metabolomics techniques have allowed for significant progress in this area. Despite numerous studies on Ulva and its tolerance to copper, no consideration has been given to potential interactions with its associated bacteria as producers of metallophores (i.e., organic ligands) that could act as a copper buffer, becoming a sequester mechanism.
Thus, using Ulva mutabilis as a model organism, an untargeted metabolomics approach including endo-metabolite extraction was applied to study Ulva‘s gametes under cupric stress EDTA was used in artificial culture medium to complex copper mimicking the function of Cu-complexing dissolved organic matter. Gametes released into a harmful (i.e. high copper concentration) environment were collected after 24 hours of incubation during their settlement. Metabolite profiling revealed a significant difference between high and low EDTA concentrations at equal total Cu concentrations, supporting our hypothesis that organic matter contributes to copper stress management in the chemosphere of Ulva.
Castilla, J. C. & E. Nealler (1978) Marine environmental impact due to mining activities of El Salvador copper mine, Chile. Marine Pollution Bulletin, 9, 67-70.
Moenne, A., M. Gómez, D. Laporte, D. Espinoza, C. A. Sáez & A. González (2020) Mechanisms of Copper Tolerance, Accumulation, and Detoxification in the Marine Macroalga Ulva compressa (Chlorophyta): 20 Years of Research. Plants, 9, 681.
Vermeer, K. & J. C. Castilla (1991) High cadmium residues observed during a pilot study in shorebirds and their prey downstream from the El salvador copper mine, Chile. Bulletin of Environmental Contamination and Toxicology, 46, 242-248.