Fate and toxicity of engineered nanomaterials in the environment: A meta-analysis.

The global environment annually receives thousands of tons of engineered nanomaterials (ENMs, particles less than 100 nm diameter). These particles have high active surface area, unique chemical properties, and can enter cells. Humanity uses many ENMs for their biological reactivity (e.g. microbicides), but their environmental effects are complex. We cataloged 2102 experimental results on whole organisms for 22 particle classes (mainly on Ag, Zn, Ti, and Cu) to assess biological responses, effective and lethal concentrations, and bioaccumulation of ENMs. Most responses were negative and varied significantly by particle type, functional group of organism, and type of response. Smaller particles tended to be more toxic. Aquatic organisms responded more negatively than did terrestrial organisms. Animals generally were most sensitive and plants least. Silver ENMs generally had the strongest negative effects. Effective and lethal concentrations generally exceeded modeled environmentally relevant concentrations and organisms usually did not accumulate or biomagnify to concentrations above those in their environment. However, most experiments lasted less than a week and were not field studies. Research to date is probably insufficient to understand chronic effects and long-term biomagnification. Numerous unique and untested ENMs continue to enter environments at accelerating rates, and our analysis indicates potential for negative effects. Our data suggest substantial research is still required to understand the ultimate influence of ENMs as they continue to accumulate in the environment. Around 40% of the papers with experimental data for ENMs failed with respect to reporting means, sample sizes, or experimental error, or they did not have proper experimental design (e.g. lack of true controls). We need more high-quality experiments that are more realistic (field or mesocosm), longer duration, contain a wider range of organisms, and account for complex food web structure.

Harmony on the prairie? Grassland plant and animal community responses to variation in climate across land-use gradients.

Human induced climate and land-use change are severely impacting global biodiversity, but how community composition and richness of multiple taxonomic groups change in response to local drivers and whether these responses are synchronous remains unclear. We used long-term community-level data from an experimentally manipulated grassland to assess the relative influence of climate and land use as drivers of community structure of four taxonomic groups: birds, mammals, grasshoppers, and plants. We also quantified the synchrony of responses among taxonomic groups across land-use gradients and compared climatic drivers of community structure across groups. All four taxonomic groups responded strongly to land use (fire frequency and grazing), while responses to climate variability were more pronounced in grasshoppers and small mammals. Animal groups exhibited asynchronous responses across all land-use treatments, but plant and animal groups, especially birds, exhibited synchronous responses in composition. Asynchrony was attributed to taxonomic groups responding to different components of climate variability, including both current climate conditions and lagged effects from the previous year. Data-driven land management strategies are crucial for sustaining native biodiversity in grassland systems, but asynchronous responses of taxonomic groups to climate variability across land-use gradients highlight a need to incorporate response heterogeneity into management planning.