Climate Change Research on the Copper River Delta: The Emerging Effect of Local Variation

Speakers: Gordon Reeves, Research Fish Biologist, Pacific Northwest Research Station; and Martin Berg, Loyola University Chicago, Chicago, IL

There are two areas of emphasis: (1) the timing of emergence of aquatic invertebrates in ponds across the entire Copper River Delta; and (2) variation in thermal regimes among streams and the associated salmon populations on the Delta.

Work in 2010 showed a strong relation between the timing and emergence of aquatic invertebrates, primarily caddisflies and Odonates (dragonflies and damselflies), and the nesting of rusty blackbirds and the fledging of their young.

Warmer winters resulting from climate change could decouple the synchronization of these events and have consequences to the nesting success of the blackbirds and other bird species that depend on the invertebrates for food and energy during reproduction.

Preliminary results show that there is a wide variation in the timing of emergence of aquatic invertebrates – emergence was 3-5 weeks later on the cooler east Delta compared to the warmer west Delta.

We also identified three general patterns of water temperature in streams on the Delta based on monitoring air temperatures and water temperatures in the water column and in the subsurface environment.

This variation suggests that the response of aquatic organisms (including salmon) to climate change will likely vary widely across the Delta, and that this local variation could mitigate the potential impacts.