Embryo development of the benthic amphipod Monoporeia affinis as a tool for monitoring and assessment of biological effects of contaminants in the field: A meta-analysis

Embryo malformations in the benthic amphipod Monoporeia affinis have been used as a biological effect indicator of chemical contaminants for more than three decades. The results from field studies along the Swedish Baltic Sea coast, comprising more than 50,000 analyzed embryos, were synthesized using a meta-analytic approach. This approach generated a quantitative and statistically defensible summary and enabled us to explore potential causative factors. The study aimed at evaluating the usefulness of embryo malformations as a biological effect indicator of chemical contaminants in the field. The result shows that malformations in M. affinis are ubiquitous in polluted areas and are negatively correlated with distance from main sources of contaminants. The result also shows that malformations are significantly more frequent up to more than 10km from point sources. We conclude that embryo malformations in M. affinis can provide useful information for management and environmental policy in the Baltic Sea region as: (1) the present study supports evidence from controlled laboratory studies that there is a cause and effect relationship between embryo malformations and contaminants; (2) the study suggests that the indicator is contaminant-sensitive and can therefore serve as an early warning of biological effects in the field; (3) the indicator is general, suggesting that it has capability to monitor and detect effects of a wide variety of known, and yet unknown, chemical contaminants. The usefulness is further strengthened by the fact that M. affinis is a widely distributed species that plays a fundamental role in the Baltic Sea ecosystem. Future research should increase the understanding of how environmental factors affect the indicator response and if the response is related to effects at lower and higher levels of biological organization.