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Landslide-dammed paleolake perturbs marine sedimentation and drives genetic change in anadromous fish

Mackey, Benjamin H. and Roering, Joshua J. and Lamb, Michael P. (2011) Landslide-dammed paleolake perturbs marine sedimentation and drives genetic change in anadromous fish. Proceedings of the National Academy of Sciences of the United States of America, 108 (47). pp. 18905-18909. ISSN 0027-8424. PMCID PMC3223463. doi:10.1073/pnas.1110445108.

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Large bedrock landslides have been shown to modulate rates and processes of river activity by forming dams, forcing upstream aggradation of water and sediment, and generating catastrophic outburst floods. Less apparent is the effect of large landslide dams on river ecosystems and marine sedimentation. Combining analyses of 1-m resolution topographic data (acquired via airborne laser mapping) and field investigation, we present evidence for a large, landslide-dammed paleolake along the Eel River, CA. The landslide mass initiated from a high-relief, resistant outcrop which failed catastrophically, blocking the Eel River with an approximately 130-m-tall dam. Support for the resulting 55-km-long, 1.3-km^3 lake includes subtle shorelines cut into bounding terrain, deltas, and lacustrine sediments radiocarbon dated to 22.5 ka. The landslide provides an explanation for the recent genetic divergence of local anadromous (ocean-run) steelhead trout (Oncorhynchus mykiss) by blocking their migration route and causing gene flow between summer run and winter run reproductive ecotypes. Further, the dam arrested the prodigious flux of sediment down the Eel River; this cessation is recorded in marine sedimentary deposits as a 10-fold reduction in deposition rates of Eel-derived sediment and constitutes a rare example of a terrestrial event transmitted through the dispersal system and recorded offshore.

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Lamb, Michael P.0000-0002-5701-0504
Additional Information:© 2011 by the National Academy of Sciences. Edited by Thomas Dunne, University of California, Santa Barbara, CA, and approved September 15, 2011 (received for review June 27, 2011). Published online before print November 14, 2011. We thank the Stewart, Lone Pine, and Island Mountain Ranches for field access. Sean Bemis processed the Center for Accelerator Mass Spectrometry ^(14)C samples. We had fruitful discussions with Harvey Kelsey and Woodward Fisher. Comments from three anonymous reviewers greatly improved this manuscript. This research was funded by National Science Foundation (NSF) Grant EAR‐0447190 (to J.J.R.), the Fulbright Earthquake Commission Scholarship from New Zealand (B.H.M.), and a Keck Institute for Space Studies Grant and NSF Grant EAR-0922199 (to M.P.L.). LiDAR data were acquired by the National Center for Airborne Laser Mapping in September 2006. Author contributions: B.H.M. and J.J.R. designed research; B.H.M. performed research; B.H.M., J.J.R., and M.P.L. analyzed data; and B.H.M. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. This article contains supporting information online at
Group:Keck Institute for Space Studies
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Fulbright Earthquake CommissionUNSPECIFIED
Keck Institute for Space Studies (KISS)UNSPECIFIED
Issue or Number:47
PubMed Central ID:PMC3223463
Record Number:CaltechAUTHORS:20111212-131555415
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Official Citation:Benjamin H. Mackey, Joshua J. Roering, and Michael P. Lamb Landslide-dammed paleolake perturbs marine sedimentation and drives genetic change in anadromous fish PNAS 2011 108 (47) 18905-18909; published ahead of print November 14, 2011, doi:10.1073/pnas.1110445108
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28426
Deposited By: Tony Diaz
Deposited On:13 Dec 2011 16:17
Last Modified:09 Nov 2021 16:57

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