New Publications

Biodiversity of freshwater diatom communities during 1000 years of metal mining, land use, and climate change in Central Sweden

Frederik De Laender and colleagues subjected a unique set of high-quality paleoecological data to statistical modeling to examine if the biological richness and evenness of freshwater diatom communities in the Falun area, a historical copper (Cu) mining region in central Sweden, was negatively influenced by 1000 years of metal exposure. Contrary to ecotoxicological predictions, we found no negative relation between biodiversity and the sedimentary concentrations of eight metals. Strikingly, our analysis listed metals (Co, Fe, Cu, Zn, Cd, Pb) or the fractional land cover of cultivated crops, meadow, and herbs indicating land disturbance as potentially promoting biodiversity. However, correlation between metal- and land-cover trends prevented concluding which of these two covariate types positively affected biodiversity. Because historical aqueous metal concentrations—inferred from solid-water partitioning—approached experimental toxicity thresholds for freshwater algae, positive effects of metal mining on biodiversity are unlikely. Instead, the positive relationship between biodiversity and historical land-cover change can be explained by the increasing proportion of opportunistic species when anthropogenic disturbance intensifies. Our analysis illustrates that focusing on the direct toxic effects of metals alone may yield inaccurate environmental assessments on time scales relevant for biodiversity conservation.

Full reference (link)

De Laender F, Verschuren D, Bindler R, Thas O, Janssen CR. 2012. Biodiversity of Freshwater Diatom Communities during 1000 Years of Metal Mining, Land Use, and Climate Change in Central Sweden. Environ. Sci. Technol. 46(16) : 9097-9105.

Identification of pathways, gene networks, paralogous gene families in Daphnia pulex responing to exposure to the toxic cyanobacterium Microcystis aeruginosa

Jana Asselman and colleagues describe in their most recent paper the implementation of a whole-genome expression microarray to identify pathways, gene networks, and paralogous gene families responsive to the toxic cyanobacterium Microcystis in the waterflea Daphnia pulex. They identified four pathways/gene networks and eight paralogous gene families affected by Microcystis. Differential regulation of the ribosome, including three paralogous gene families encoding 40S, 60S, and mitochondrial ribosomal proteins, suggests an impact of Microcystis on protein synthesis of D. pulex. In addition, differential regulation of the oxidative phosphorylation pathway (including the NADH:ubquinone oxidoreductase gene family) and the trypsin paralogous gene family (a major component of the digestive system in D. pulex) could explain why fitness is reduced based on energy budget considerations.

Full reference (link)

Asselman J, De Coninck D, Glaholt S, Colbourne JK, Janssen CR, Shaw JR, De Schamphelaere KAC. 2012. Identification of Pathways, Gene Networks, and Paralogous Gene Families in Daphnia pulex Responding to Exposure to the Toxic Cyanobacterium Microcystis aeruginosa. Environ. Sci. Technol. 46(15) : 8448–8457.