The ninespine stickleback as a model organism in arctic ecotoxicology

Background: The Arctic is subject to atmospheric deposition of persistent organic pollutants through the process of global distillation. It also contains thousands of sites with local sources of contamination, including military installations, mining operations, and petroleum extraction facilities. Pollutants accumulate in surface waters. Aim: To investigate the utility of ninespine stickleback (Pungitius pungitius) as a sentinel fish species to monitor the presence and biological effects of chemical contamination in the Arctic. Organism: Pungitius pungitius is a circumpolar species that occurs in freshwater, brackish water, and marine habitats. It is often the most abundant fish present. It appears to be relatively hardy with respect to potentially lethal effects of contaminants, which allows investigation of perturbed biological processes such as endocrine, gene expression, and developmental disruption. Biomarker development: We developed a homologous vitellogenin assay for the ninespine stickleback to assess the presence of estrogen-modulating contaminants in surveys of arctic contaminated sites. We also validated a thyroxine (T₄) assay for the ninespine stickleback to enable investigations of thyroid-disrupting contaminants. We review recent work that demonstrates the efficacy of transcriptional profiling to identify disrupted gene networks by finding functionally related groups of genes that are up-or down-regulated due to contaminant exposure. Results and conclusions: We collected spatially explicit contaminated site data for the Arctic and found that more contaminated sites lie within the distribution of the ninespine stickleback than within that of the threespine stickleback. This biogeographic advantage combined with a suite of biomonitoring tools makes the ninespine stickleback a suitable model organism for studying contaminants in marine, brackish, and fresh waters throughout the Arctic.