Local contamination in relation to population genetic diversity and resilience of an arctic marine amphipod

The objective of this study was to investigate whether populations inhabiting a contaminated environment are affected in terms of decreased genetic diversity due to selection of tolerant genotypes and if such effect carries a cost. Marine arctic amphipod populations (Orchomenella pinguis) were collected from sites within a contaminated fjord, as well as from sites outside the fjord on the west-coast of Greenland over three years (2006–2008). Impacts on genetic diversity, effects on resilience such as development of tolerance and cost were determined. AFLP-analysis was used to explore within and between population genetic diversity, and exposure studies were performed where the populations were subjected to known and unknown stressors to assess resilience. Populations collected at three contaminated sites all had reduced genetic diversity in 2007 compared to populations outside the fjord. This pattern was different in 2008 as all contaminated site populations increased in diversity, whereas a decrease in diversity occurred at the outer sites. However, tolerance, but even more so, cost, was related to contamination exposure in 2008, in spite of the shift in genetic diversity. We suggest that contamination rapidly induces effects that can be captured as tolerance and associated cost, whereas effects on genetic diversity can be difficult to separate from recent migration events that dilute eventual decreases in diversity due to contamination pressure. As long as impacted populations can be influenced by migration events that increase the genetic diversity and add health to an affected population, populations in contaminated areas may have enhanced probability of survival.

► Populations of the marine amphipod Orchomenella pinguis were collected at contaminated and clean sites in 2006–2008.
► We assessed contamination effects on genetic diversity as well as on resilience such as development of tolerance and cost.
► Effects on resilience can be rapidly detected, while effect on genetic diversity is hampered by migration events.