Subsurface biogeochemistry is a missing link between ecology and hydrology in dam-impacted river corridors
- Published
- Accepted
- Subject Areas
- Ecosystem Science, Freshwater Biology, Biogeochemistry, Ecohydrology, Food, Water and Energy Nexus
- Keywords
- hyporheic zone, hydropeaking, groundwater-surface water mixing, temperature, organic matter, biogeochemical hotspot
- Copyright
- © 2018 Graham et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2018. Subsurface biogeochemistry is a missing link between ecology and hydrology in dam-impacted river corridors. PeerJ Preprints 6:e27147v2 https://doi.org/10.7287/peerj.preprints.27147v2
Abstract
Global investment in hydropower is rapidly increasing, fueled by a need to manage water availability and by incentives promoting renewable energy sources. This expansion poses unrecognized risks to the world’s vulnerable freshwaters. While many hydropower impacts have been investigated, dam-induced alterations to subsurface processes influence river corridor ecosystem health in ways that remain poorly understood. We advocate for a better understanding of dam impacts on subsurface biogeochemical activity, its connection to hydrology, and follow-on trophic cascades within the broader river corridor. We delineate an integrated view of hydropower impacts in which dam-induced changes to surface water flow regimes generate changes in surface-subsurface hydrologic exchange flows (HEFs) that subsequently (1) regulate resource availability for benthic microorganisms at the base of aquatic food webs and (2) impose kinetic constraints on biogeochemical reactions and organismal growth across a range of trophic levels. These HEF-driven effects on river corridor food webs, as mediated by subsurface biogeochemistry, are a key knowledge gap in our assessment of hydropower sustainability and putatively combine with other, more well-known dam impacts to result in significant changes to river corridor health. We suggest targeted laboratory and field-based studies to link hydrobiogeochemical models used to predict heat transport, biogeochemical rates, and hydrologic flow with ecological models that incorporate biomass changes in specific categories of organisms. Doing so will enable predictions of feedbacks among hydrology, temperature, biogeochemical rates, organismal abundances, and resource transfer across trophic levels. An understanding of dam impacts on subsurface hydrobiogeochemistry and its connection to the broader aquatic food web is fundamental to enabling mechanism-based decision making for sustainable hydropower operations.
Author Comment
This manuscript has been re-structured and revised to provide additional explanation.