| Title | Environmental heterogeneity and community structure of the Kobuk River, Alaska, in response to climate change |
| Publication Type | Journal Article |
| Year of Publication | 2011 |
| Authors | Durand, J. R., Lusardi R. A., Nover D., Suddeth R., Carmona-Catot G., Connell-Buck C., Gatzke S., Katz J. V. E., Mount JF., Moyle P. B., & Viers J. H. |
| Journal | Ecosphere |
| Volume | 2 |
| Issue | 4 |
| Pagination | 1-19 |
| Date Published | 4/2011 |
| Keywords | Alaska, climate change, ecosystem function, fish biology, flow-pulse, food webs, hydro-geomorphology, permafrost, sub-Arctic, thermokarst |
| Abstract | The Kobuk River runs west along the southern Brooks Range from Gates of the Arctic
National Park in Alaska, USA, to the Chukchi Sea. It is highly vulnerable to changes in climate due to its
sub-Arctic location, unique geography, and permafrost foundation. Combined with its pristine condition,
these qualities make the Kobuk an ideal system upon which to build a conceptual model for predicting
ecosystem effects of climate change. We constructed a conceptual ecosystem model for the Kobuk River
synthesizing surveyed baseline hydrologic, geomorphic and biotic conditions with literature on Arctic
rivers. While the mainstem Kobuk has limited biological productivity, it provides spawning habitat and
connectivity for large resident and migratory fish that rely upon off-channel habitat for food resources.
System function is dependent largely on intermittent pulse flows that connect riverine habitats, allowing
periods of late summer high productivity in off-channel habitat. Spring break-up and hill slope processes
are critically important for maintaining habitat complexity and inter-connectivity. Climate change models
predict the region will experience a disproportionate increase in average winter air temperature relative to
summer temperatures, in the number of ice-free days, and in annual rainfall. Our conceptual model
predicts that changes to fish and invertebrate populations on the Kobuk River will result not from
physiological responses to increased temperatures, but rather to shifts in two main physical drivers: 1)
spring break-up intensity, resulting in changes to scour rate and sediment deposition; and 2) discontinuous
permafrost melt, resulting in widespread heterogeneous zones of active layer thickening and
thermokarsting. The interaction of these two drivers offers four potential scenarios of geomorphic change
in the system and four dramatically different biological outcomes. This model should help managers and
scientists evaluate the magnitude and direction of ecosystem changes as they occur within the Kobuk
system and potentially other sub-Arctic river systems. |
| URL | http://www.esajournals.org/doi/pdf/10.1890/ES10-00111.1 |
| DOI | 10.1890/ES10-00111.1 |
