Multi-omics eco-surveillance of complex legacy contamination with a locally adapted estuarine invertebrate

Time-course of oral toxicity to contaminated groundwater in male Sprague Dawley rats

Assessing toxicity of complex mixtures of contaminants from industrial sites with historic and ongoing contamination remains a challenge for risk assessors. Groundwater from a pesticide packaging site in Canada containing a complex mixture of known and unknown contaminants was examined in male rats to determine the target organ toxicity. This study determined the time-course of toxicity (7, 14, 28, and 60 days) following ad libitum oral exposure to 0.05% v/v contaminated groundwater compared to tap water (control) in male Sprague Dawley rats (n=5 /group/time). Exposure to groundwater resulted in inflammation, indicated by a statistically significant increase in plasma lymphocyte and neutrophil counts on days 7 and 60, respectively, but a reduction in the plasma alpha 2 macroglobulin levels by day 60. Gonadotoxicity was indicated by a reduced Johnsen score (grading spermatogenesis) in all exposed groups at all time points, while seminiferous epithelial height was reduced on days 7, 14, and 28 compared to controls. Plasma testosterone was reduced in exposed groups on days 7 and 28, accompanied by elevated testicular lipid peroxidation at all time points compared to control. In contrast, lipid peroxidation in the lungs from exposed rats was elevated on days 7, 14, and 28. Plasma symmetric dimethylarginine was elevated on day 14 in the exposed group indicating renal impairment. Taken together, these results indicate that testes, kidney, immune and lung are target organs for the contaminated groundwater from this industrial site. The current study highlights the challenge in hazard assessment for complex mixtures and highlights the need for effects-directed analysis and the continued, albeit limited, use of animal models in toxicity testing.

Multiple-biomarkers show the importance of blue carbon to commercially important fishery species

Coastal blue carbon ecosystems (BCE) support nearshore food webs and provide habitat for many commercially important fish and crustacean species. However, the complex links between catchment vegetation and the carbon food-base of estuarine systems are difficult to disern. We employed a multi-biomarker approach (stable isotope ratios - δ¹³C and δ¹⁵N, fatty acid trophic markers - FATMs and metabolomics - central carbon metabolism metabolites) to test links between estuarine vegetation and the food sources available to commercially important crabs and fish occurring within the river systems of the near-pristine eastern coastline of the Gulf of Carpentaria, Australia. Stable isotope analysis confirmed the dietary importance of fringing macrophytes to consumer diet, but showed that this is modulated by their dominance along the riverbank. FATMs indicative of specific food sources further confirmed the differences among upper intertidal macrophytes (driven by concentrations of 16: 1ω7, 18:1ω9, 18:2ω6, 18:3ω3 & 22.0) and seagrass (driven by 18:2ω6, 18:3ω3). These dietary patterns were also reflected in the concentration of central carbon metabolism metabolites. Overall, our study demonstrates the congruence of different biomarker approaches to resolve biochemical links between blue carbon ecosystems and important nekton species, and provides fresh insights into the pristine tropical estuaries of northern Australia.