Element concentrations, histology and serum biochemistry of arctic char (Salvelinus alpinus) and shorthorn sculpins (Myoxocephalus scorpius) in northwest Greenland

The increasing exploratory efforts in the Greenland mineral industry, and in particular, the proposed rare earth element (REE) mining projects, requires an urgent need to generate data on baseline REE concentrations and their potential environmental impacts. Herein, we have investigated REE concentrations in anadromous Arctic char (Salvelinus alpinus) and shorthorn sculpins (Myoxocephalus scorpius) from uncontaminated sites in Northwest Greenland, along with the relationships between the element concentrations in gills and liver, and gill histology and serum biochemical parameters. Concentrations of arsenic, silver, cadmium, cerium, chromium, copper, dysprosium, mercury, lanthanum, neodymium, lead, selenium, yttrium, and zinc in gills, liver and muscle are presented. No significant statistical correlations were observed between element concentrations in different organs and gill histology or serum biochemical parameters. However, we observed positive relationships between age and histopathology, emphasizing the importance of including age as a co-variable in histological studies of fish. Despite no element-induced effects were observed, this study is considered an important baseline study, which can be used as a reference for the assessment of impacts of potential future REE mine sites in Greenland

Development, standardization and refinement of procedures for evaluating effects of endocrine active compounds on development and sexual differentiation of Xenopus laevis

Xenopus laevis has been introduced as a model to study effects of endocrine-active compounds (EAC) on development and sexual differentiation. However, variable and inconsistent data have raised questions about the reliability of the test methods applied. The current study was conducted in two laboratories to develop, refine, and standardize procedures and protocols. Larvae were exposed in flow-through systems to 17β-estradiol (E2), at concentrations from 0.2 to 6.0 μg E2 L−1 in Experiment 1A, and 0.015 to 2.0 μg E2 L−1 in Experiment 1B. In both studies survival (92%, 99%) and percentage of animals that completed metamorphosis (97%, 99%) indicated reproducible biological performance. Furthermore, minor variations in husbandry led to significant differences in snout-to-vent length, weight, and gonad size. In Experiment 1A, almost complete feminization occurred in all E2 treatment groups whereas a concentration response was observed in Experiment 1B resulting in an EC50 of 0.12 μg E2 L−1. The final verified protocol is suitable for determining effects of EAC on development and sexual differentiation in X. laevis