Oxygen deprivation tampers with sex hormones in fish and impairs reproduction, according to new research. The results suggest that low oxygen in freshwater ecosystems can disrupt animals' endocrine systems. Researchers say this link might explain the ongoing decline in some fish and amphibian species.
Various pesticides, components of plastics, and other chemical pollutants known collectively as endocrine disruptors mimic natural hormones such as estrogen.
Scientists have linked such contaminants to reproductive failures in many animals and
to oddities ranging from deformities in frogs to sex changes in fish. The disruptors are also suspected of underlying some breast cancer in women.