Potential impacts of engineered nanomaterials on the marine environment are largely unknown. Determining these impacts is a complicated endeavor, made more difficult by the large diversity in nanomaterial structure and composition, as well as fate and transport in different environments. These physicochemical criteria combine to determine the biological interactions, or toxicity. We have examined the effects of exposure to ZnO, CuO, CeO2 and Ag nanomaterials on marine phytoplankton. Phytoplankton are fundamental to assessing ocean health as they are the basis of most marine foodwebs, so even subtle changes in growth rates can have large outcomes when scaled up to population or ecosystem levels. Endpoints examined in this study were chosen with the aim of linking cellular targets of toxicity with population and ecosystem level effects so as to provide a broad scale perspective on this issue. We have adapted a suite of fluorescence based assays for cellular targets of cytotoxicity in two species of phytoplankton. These assays can be performed in high-content screens using a fluorescence plate reader, thus facilitating rapid and inexpensive examination of a large number of nanomaterials. Specific cytotoxicity targets include reactive oxygen species production, mitochondrial membrane potential and cell death. To link these toxicity endpoints to cellular processes we have measured the subcellular localization of nanomaterials in different organelles. From the impacts to organelles and individual cells, we scaled up to measure growth rate and photosynthetic efficiency. These represent the major ecological functions of phytoplankton, so by determining the impacts of nanomaterials on these parameters we can statistically model population-level effects, as well as predicting ecosystem-wide impacts. In combination with chemical descriptions of nanomaterial fate and transport, these approaches provide a framework for assessing the environmental impacts of nanomaterials on marine phytoplankton across a broad yet interdependent range of scales.

Impacts of engineered nanomaterials on marine phytoplankton across levels of biological organization

248th National Meeting (2014)

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