Impacts of climate change on hypersaline conditions of estuaries and xenobiotic toxicity

Climate change has had significant impacts on the hydrologic cycle of the planet. Of particular concern are estuarine environments, such as San Francisco Bay (USA) which is fed by diminishing snow pack runoff leading to gradual increases in salinity. Salinity enhances the acute toxicity of several agricultural chemicals in anadromous fish through augmented biochemical activation catalyzed by enzymes that are induced during hypersaline acclimation. This review discusses the mechanisms of the enhanced toxicity, the enzymes involved and the regulation of the enzymes by hypersaline conditions. Given the rapid changes taking place in the world's waterways, environmental modification of toxicological pathways should be a significant focus of the research community as the toxicity of multiple xenobiotics may be enhanced.