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Marie Noele Croteau, Ph.D.

Marie came to the USGS in September 2002 as a postdoctoral fellow to study the bioavailability and bioaccumulation of metals in freshwater food webs. Her work focused on understanding how metals are transferred through food webs and how trophic position in a food web influences exposure to metals.

Marie used nitrogen and carbon stable isotopes to show that cadmium, in contrast to copper, could be magnified along certain freshwater food webs. This suggests that processes that drive Cd trophic transfer are more complex than that of organo-metals, metalloids and organic contaminants.

In addition to her work on metal trophic transfer, she refined an approach that involves the use stable metal isotopes (rather than radioisotopes) to describe accumulation and loss dynamics in freshwater invertebrates. Characterization of bioaccumulation dynamics is critical to understanding risks associated with contaminant exposure in organisms. For instance, this tracing technique allowed showing that a slow rate constant of loss for Cu likely explains the elevated levels of this toxic trace metal found in molluscs in nature, and that diet is an important bioaccumulation pathway for metals for several aquatic species.

She used biodynamic modeling and the enriched stable isotope tracers in novel ways to understand the fate and effects of nanosized metals in aquatic organisms as well as to investigate how the geochemical properties of mineral particles consumed by organisms affect their bioavailability.