Suchergebnisse

Streams play a key role in the global carbon cycle. The balance between carbon intake through photosynthesis and carbon release via respiration influences carbon emissions from streams and depends on temperature. However, the lack of a comprehensive analysis of the temperature sensitivity of the metabolic balance in inland waters across latitudes and local climate conditions hinders an accurate projection of carbon emissions in a warmer future. Here, we use a model of diel dissolved oxygen dynamics, combined with high-frequency measurements of dissolved oxygen, light and temperature, to estimate the temperature sensitivities of gross primary production and ecosystem respiration in streams across six biomes, from the tropics to the arctic tundra. We find that the change in metabolic balance, that is, the ratio of gross primary production to ecosystem respiration, is a function of stream temperature and current metabolic balance. Applying this relationship to the global compilation of stream metabolism data, we find that a 1 degrees C increase in stream temperature leads to a convergence of metabolic balance and to a 23.6% overall decline in net ecosystem productivity across the streams studied. We suggest that if the relationship holds for similarly sized streams around the globe, the warming-induced shifts in metabolic balance will result in an increase of 0.0194 Pg carbon emitted from such streams every year. ; National Science Foundation (NSF)National Science Foundation (NSF) [EF-1258994]; NSFNational Science Foundation (NSF) [EF-1065255, EF-1065286, EF-1065055, EF-1065682, EF-1065267, EF-1064998, EF-1065377]; Northern Australian Environmental Resources Hub of the National Environmental Science Program; Scale, Consumers and Lotic Ecosystem Rates project ; The authors thank K. Gido for his contribution in obtaining funding and designing the field experiments. K. Gido, J. Drake, C. Osenberg and J. Minucci provided comments on earlier versions of this paper. Georgia Advanced Computing Resource Center provided the computing facility. This study was supported by the National Science Foundation (NSF, grant EF-1258994) and is part of the Scale, Consumers and Lotic Ecosystem Rates project supported by NSF grant EF-1065255. Data collection at each site was supported by NSF grants EF-1065286, EF-1065055, EF-1065682, EF-1065267, EF-1064998 and EF-1065377, and the Northern Australian Environmental Resources Hub of the National Environmental Science Program. ; Public domain authored by a U.S. government employee