Subsurface biogeochemistry is a missing link between ecology and hydrology in dam-impacted river corridors

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.

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Subsurface biogeochemistry is a missing link between ecology and hydrology in dam-impacted river corridors

10.7287/peerj.preprints.27147v2 ◽

2018 ◽

Author(s):

Emily B Graham ◽

James C Stegen ◽

Maoyi Huang ◽

Xingyuan Chen ◽

Timothy Scheibe

Keyword(s):

Food Webs ◽

Renewable Energy Sources ◽

Trophic Levels ◽

Surface Water Flow ◽

Dam Impacts ◽

Aquatic Food ◽

Hydropower Impacts ◽

Hydrologic Exchange ◽

Induced Changes ◽

River Corridor

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Subsurface biogeochemistry is a missing link between ecology and hydrology in dam-impacted river corridors

10.7287/peerj.preprints.27147v1 ◽

2018 ◽

Author(s):

Emily B Graham ◽

James C Stegen ◽

Maoyi Huang ◽

Xingyuan Chen ◽

Timothy Scheibe

Keyword(s):

Food Webs ◽

Renewable Energy Sources ◽

Trophic Levels ◽

Surface Water Flow ◽

Dam Impacts ◽

Aquatic Food ◽

Hydropower Impacts ◽

Hydrologic Exchange ◽

Induced Changes ◽

River Corridor

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. In particular, subsurface processes are altered by dam operations and may 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.

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Elevated temperature and browning increase dietary methylmercury, but decrease essential fatty acids at the base of lake food webs

Scientific Reports ◽

10.1038/s41598-021-95742-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Pianpian Wu ◽

Martin J. Kainz ◽

Fernando Valdés ◽

Siwen Zheng ◽

Katharina Winter ◽

...

Keyword(s):

Climate Change ◽

Fatty Acids ◽

Organic Matter ◽

Food Webs ◽

Essential Fatty Acids ◽

Trophic Levels ◽

Climate Change Scenarios ◽

Essential Nutrients ◽

Aquatic Food Webs ◽

Aquatic Food

AbstractClimate change scenarios predict increases in temperature and organic matter supply from land to water, which affect trophic transfer of nutrients and contaminants in aquatic food webs. How essential nutrients, such as polyunsaturated fatty acids (PUFA), and potentially toxic contaminants, such as methylmercury (MeHg), at the base of aquatic food webs will be affected under climate change scenarios, remains unclear. The objective of this outdoor mesocosm study was to examine how increased water temperature and terrestrially-derived dissolved organic matter supply (tDOM; i.e., lake browning), and the interaction of both, will influence MeHg and PUFA in organisms at the base of food webs (i.e. seston; the most edible plankton size for zooplankton) in subalpine lake ecosystems. The interaction of higher temperature and tDOM increased the burden of MeHg in seston (< 40 μm) and larger sized plankton (microplankton; 40–200 μm), while the MeHg content per unit biomass remained stable. However, PUFA decreased in seston, but increased in microplankton, consisting mainly of filamentous algae, which are less readily bioavailable to zooplankton. We revealed elevated dietary exposure to MeHg, yet decreased supply of dietary PUFA to aquatic consumers with increasing temperature and tDOM supply. This experimental study provides evidence that the overall food quality at the base of aquatic food webs deteriorates during ongoing climate change scenarios by increasing the supply of toxic MeHg and lowering the dietary access to essential nutrients of consumers at higher trophic levels.

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Selenium Interactions with Algae: Chemical Processes at Biological Uptake Sites, Bioaccumulation, and Intracellular Metabolism

Plants ◽

10.3390/plants9040528 ◽

2020 ◽

Vol 9 (4) ◽

pp. 528 ◽

Cited By ~ 2

Author(s):

Dominic E. Ponton ◽

Stephanie D. Graves ◽

Claude Fortin ◽

David Janz ◽

Marc Amyot ◽

...

Keyword(s):

Food Webs ◽

Mechanistic Model ◽

Trophic Levels ◽

Primary Producers ◽

Organic Selenium ◽

Selenium Uptake ◽

Aquatic Food Webs ◽

Uptake Sites ◽

Aquatic Food ◽

Lentic Systems

Selenium (Se) uptake by primary producers is the most variable and important step in determining Se concentrations at higher trophic levels in aquatic food webs. We gathered data available about the Se bioaccumulation at the base of aquatic food webs and analyzed its relationship with Se concentrations in water. This important dataset was separated into lotic and lentic systems to provide a reliable model to estimate Se in primary producers from aqueous exposure. We observed that lentic systems had higher organic selenium and selenite concentrations than in lotic systems and selenate concentrations were higher in lotic environments. Selenium uptake by algae is mostly driven by Se concentrations, speciation and competition with other anions, and is as well influenced by pH. Based on Se species uptake by algae in the laboratory, we proposed an accurate mechanistic model of competition between sulfate and inorganic Se species at algal uptake sites. Intracellular Se transformations and incorporation into selenoproteins as well as the mechanisms through which Se can induce toxicity in algae has also been reviewed. We provided a new tool for risk assessment strategies to better predict accumulation in primary consumers and consequently to higher trophic levels, and we identified some research needs that could fill knowledge gaps.

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Assessing plastic debris in aquatic food webs: what we know and don’t know about uptake and trophic transfer

Environmental Reviews ◽

10.1139/er-2018-0079 ◽

2019 ◽

Vol 27 (3) ◽

pp. 304-317 ◽

Cited By ~ 24

Author(s):

J.F. Provencher ◽

J. Ammendolia ◽

C.M. Rochman ◽

M.L. Mallory

Keyword(s):

Food Webs ◽

Trophic Transfer ◽

Global Scale ◽

Trophic Levels ◽

Published Data ◽

Plastic Pollution ◽

Diverse Range ◽

Global Environmental Issue ◽

Freshwater Biota ◽

Aquatic Food

Plastic pollution is now recognized as a global environmental issue that can affect the health of biota and ecosystems. Now that a growing number of species and taxa are known to ingest a diverse range of sizes and types of plastics and retain the plastics in their guts, there are increasing questions relating to the movement of plastics through food webs, and how biota may directly and indirectly ingest plastics. Here, we synthesize what is known from the published, peer-reviewed literature about plastic ingestion by animals and identify critical gaps in our knowledge. We systematically reviewed and examined the literature for studies that reported ingested plastics in marine and freshwater biota at a global scale. Our objective was to inform discussions and future studies regarding what we know about plastic ingestion and fate in food webs. We assessed what regions, ecosystems, and food webs have been studied to date and whether potential information may already be available to assess if trophic transfer of plastics may be occurring. We found 160 relevant publications through 2016. Most studies were concentrated in specific regions and in specific ecosystem types, with freshwater studies being the most limited. Moreover, most studies examined one species at a time with only a handful of regions with multiple taxa examined across multiple studies. Twenty-one percent of the regions have no published data on plastic ingestion to date. Although some studies have measured ingestion in multiple species across trophic levels, few have tested the hypothesis that plastics are transferred across trophic levels. Moreover, none have addressed questions related to biomagnification. While our review suggests that numerous papers have recorded the ingestion of plastics by biota across many trophic levels, habitats, and geographic regions, many questions regarding how or whether biota retain, bioaccumulate, biomagnify, and trophically transfer plastics still need to be addressed.

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Where are the decomposers? Uncovering the soil food web of a tropical montane rain forest in southern Ecuador using stable isotopes (15N)

Journal of Tropical Ecology ◽

10.1017/s0266467405002646 ◽

2005 ◽

Vol 21 (5) ◽

pp. 589-593 ◽

Cited By ~ 54

Author(s):

Jens Illig ◽

Reinhard Langel ◽

Roy A. Norton ◽

Stefan Scheu ◽

Mark Maraun

Keyword(s):

Food Webs ◽

Animal Species ◽

Nutrient Status ◽

Trophic Levels ◽

Trophic Relationships ◽

Montane Rain Forest ◽

Large Numbers ◽

Southern Ecuador ◽

Aquatic Food ◽

Taxonomic Affiliation

Trophic relationships among animals, plants and microflora are the basis for the construction of terrestrial and aquatic food webs, but both the structure and dynamics of food webs remain contentious. Examples of issues include how the overall nutrient status of a system affects the number of trophic levels, whether trophic-level omnivory and intraguild predation are rare or important, if different animal species can be aggregated into functional groups according to their taxonomic affiliation, how large numbers of decomposer animal species can coexist and why there are so many parthenogenetic taxa in soil.

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In situ assessment of trophic levels and transfer rates in aquatic food webs, using chronic (Hg) and pulsed (Chernobyl137Cs) contaminants

SIL Proceedings 1922-2010 ◽

10.1080/03680770.1989.11899211 ◽

1991 ◽

Vol 24 (5) ◽

pp. 2970-2975 ◽

Cited By ~ 3

Author(s):

Markus Meili

Keyword(s):

Food Webs ◽

Trophic Levels ◽

Transfer Rates ◽

Aquatic Food Webs ◽

In Situ Assessment ◽

Aquatic Food

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Modelling the role of highly unsaturated fatty acids in planktonic food web processes: a mechanistic approach

Environmental Reviews ◽

10.1139/a2012-007 ◽

2012 ◽

Vol 20 (3) ◽

pp. 155-172 ◽

Cited By ~ 27

Author(s):

Gurbir Perhar ◽

George B. Arhonditsis ◽

Michael T. Brett

Keyword(s):

Fatty Acids ◽

Food Webs ◽

Unsaturated Fatty Acids ◽

Trophic Levels ◽

Efficient Energy Transfer ◽

Highly Unsaturated Fatty Acids ◽

Planktonic Food ◽

Aquatic Food ◽

Biochemical Research

Highly unsaturated fatty acids (HUFAs) are a subgroup of fatty acids characterized by chains of 20 or more carbon atoms with multiple double bonds, which potentially limit the growth of zooplankton. Zooplankton require high HUFA concentrations during periods of rapid growth, but co-limitation with nutrients is also likely to occur. Recent modelling results suggest food webs with high quality (nutritional and biochemical) primary producers can attain inverted biomass distributions with efficient energy transfer between trophic levels. In this study, our objective is to highlight the recent advances in studying the role of HUFAs in aquatic food webs. We take a first-principles approach to investigate the chemical nature of HUFAs, and the role they play in zooplankton ecology. To this end, we introduce a novel zooplankton growth sub model that tracks the interplay between nitrogen, phosphorus, and HUFAs in plankton population models. Our aim is to produce a sub model that incorporates the knowledge gained from decades of biochemical research into management-oriented predictive tools.

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