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Abstract Climate change in the Arctic is altering watershed hydrologic processes and biogeochemistry. Here, we present an emergent threat to Arctic watersheds based on observations from 75 streams in Alaska’s Brooks Range that recently turned orange, reflecting increased loading of iron and toxic metals. Using remote sensing, we constrain the timing of stream discoloration to the last 10 years, a period of rapid warming and snowfall, suggesting impairment is likely due to permafrost thaw. Thawing permafrost can foster chemical weathering of minerals, microbial reduction of soil iron, and groundwater transport of metals to streams. Compared to clear reference streams, orange streams have lower pH, higher turbidity, and higher sulfate, iron, and trace metal concentrations, supporting sulfide mineral weathering as a primary mobilization process. Stream discoloration was associated with dramatic declines in macroinvertebrate diversity and fish abundance. These findings have considerable implications for drinking water supplies and subsistence fisheries in rural Alaska. 

We compare behavior of two person teams with individuals in indefinitely repeated prisoner dilemma games with perfect monitoring. Team discussions are used to understand the rationale underlying these choices, and how these choices come about. There are three main findings: (1) Teams learned to cooperate faster than individuals, and cooperation was more stable for teams. (2) Strategies identified from team dialogues differ from those identified by the Strategy Frequency Estimation Method. This reflects the improvisational nature of teams’ decision making. (3) Increasing cooperation was primarily driven by teams unilaterally cooperating in the hope of inducing their opponent to cooperate.