PeerJ Preprints: Food, Water and Energy Nexushttps://peerj.com/preprints/index.atom?journal=peerj&subject=1436Food, Water and Energy Nexus articles published in PeerJ PreprintsBacillus induced to biosynthesize VOCs & nitriles may benefit agriculture.https://peerj.com/preprints/26112019-09-302019-09-30Guenevere PerryDiane Perry
The scope of the project was to identify the possible agricultural applications for bacteria induced to synthesize nitriles and VOCs. The study was randomized. Cucurbit seeds and Bacillus licheniformis were selected as the plant and microbial models for two trial studies. In trial 1, 90 cucumber seeds were cultured with B.licheniformis induced to synthesize VOCs (including ethanol, 3-methyl-1-butanol, pentanol), esters (ethyl acetate), and acetonitriles. After 2 weeks the induced bacteria increased seed germination by 68% compared to control samples. Several seedlings were transferred to a small garden, infested with soil nematodes. Roots of control and induced samples appeared affected. Control samples appeared stunted in growth with decreased productivity, but cucumber plants initially planted with induced bacteria were noticeably larger in size with good productivity. Induced Bacillus increased the number of blossoms and cucumber per plant by 125% compared to control samples. Induced Bacillus did not increase solubility of nitrogen, phosphorous, or potassium in the soil, but appeared to increase plant health and defenses against pathogenic infections. Though the study findings are preliminary, soil microbes induced to synthesize VOCs and nitriles may improve plant health and productivity in cucurbit plants.
The scope of the project was to identify the possible agricultural applications for bacteria induced to synthesize nitriles and VOCs. The study was randomized. Cucurbit seeds and Bacillus licheniformis were selected as the plant and microbial models for two trial studies. In trial 1, 90 cucumber seeds were cultured with B.licheniformis induced to synthesize VOCs (including ethanol, 3-methyl-1-butanol, pentanol), esters (ethyl acetate), and acetonitriles. After 2 weeks the induced bacteria increased seed germination by 68% compared to control samples. Several seedlings were transferred to a small garden, infested with soil nematodes. Roots of control and induced samples appeared affected. Control samples appeared stunted in growth with decreased productivity, but cucumber plants initially planted with induced bacteria were noticeably larger in size with good productivity. Induced Bacillus increased the number of blossoms and cucumber per plant by 125% compared to control samples. Induced Bacillus did not increase solubility of nitrogen, phosphorous, or potassium in the soil, but appeared to increase plant health and defenses against pathogenic infections. Though the study findings are preliminary, soil microbes induced to synthesize VOCs and nitriles may improve plant health and productivity in cucurbit plants.Proximate composition and quantitative analysis of benzoyl peroxide and benzoic acid in the wheat flour samples: wheat flour qualityhttps://peerj.com/preprints/279692019-09-182019-09-18Numrah NisarFaiza MustafaArifa TahiraRashad Waseem Khan QadriYaodong YangMuhammad Imran Khan
Background. Extensive milling processes have deprived wheat flour from essential nutrients. Objective of the current study was to assess the nutritive quality of commercial wheat flour (soft flour/SF) through analyses of proximate composition and functional properties as well as quantification of benzoyl peroxide (BP; added as bleaching agent in the SF). Methods. Test samples included commercial soft flour samples purchased from the local supplier from different flour mills (with additives) and a control sample without additives was prepared by grinding the seeds harvested from wheat crop grown in the experimental field of University of Agriculture, Faisalabad, under optimized field conditions without any fertilizer and insecticide. Benzoyl peroxide and Benzoic Acid quantification was performed through High Performance Liquid Chromatography Results. Results when compared with the whole wheat flour (WF; never received additives) indicated that SF had lesser fiber, protein and ash contents, whereas, higher damaged starch, fat, gluten and bulk density. A parallel experiment under selected conditions (temperature, time and solute concentration) showed dissociation of BP into BA soon after the exposure. Observed BA range (13.77 mg/g after 16hrs) in SF and exposure level assessment (44.3±1.36 mg/kg/BW) showed higher intake of BA on the consumption of SF. Results revealed superiority of WF over SF in nutritive qualities as well as free of toxicants such as BA. KEYWORDS: Benzoyl peroxide; Benzoic acid; Soft Flour; Whole Wheat Flour; High Performance Liquid Chromatography
Background. Extensive milling processes have deprived wheat flour from essential nutrients. Objective of the current study was to assess the nutritive quality of commercial wheat flour (soft flour/SF) through analyses of proximate composition and functional properties as well as quantification of benzoyl peroxide (BP; added as bleaching agent in the SF). Methods. Test samples included commercial soft flour samples purchased from the local supplier from different flour mills (with additives) and a control sample without additives was prepared by grinding the seeds harvested from wheat crop grown in the experimental field of University of Agriculture, Faisalabad, under optimized field conditions without any fertilizer and insecticide. Benzoyl peroxide and Benzoic Acid quantification was performed through High Performance Liquid Chromatography Results. Results when compared with the whole wheat flour (WF; never received additives) indicated that SF had lesser fiber, protein and ash contents, whereas, higher damaged starch, fat, gluten and bulk density. A parallel experiment under selected conditions (temperature, time and solute concentration) showed dissociation of BP into BA soon after the exposure. Observed BA range (13.77 mg/g after 16hrs) in SF and exposure level assessment (44.3±1.36 mg/kg/BW) showed higher intake of BA on the consumption of SF. Results revealed superiority of WF over SF in nutritive qualities as well as free of toxicants such as BA. KEYWORDS: Benzoyl peroxide; Benzoic acid; Soft Flour; Whole Wheat Flour; High Performance Liquid ChromatographyPublic priorities on locally-driven sea level rise planning on the East Coast of the United Stateshttps://peerj.com/preprints/279332019-09-022019-09-02Adam T Carpenter
Sea Level Rise poses a substantial concern to communities worldwide. Increased inundation, storm surge, salt water intrusion, and other impacts create challenges which will require considerable planning to address. Recognizing the broad and differing scope of sea level rise issues and the variability of policy options to address them, local planning frameworks are necessary in addition to tools and resources available from state and federal governments. To help assess priorities and preferences on sea level rise planning, a survey of 503 persons affiliated with coastal communities on the East Coast of the United States was conducted in December 2017. This survey studied key aspects locally-driven sea level rise plans, including planning priorities, funding options, methods to resolve conflict, and potential responses. Six key findings address these and other concerns to provide the foundation of a locally driven framework for public officials.
Sea Level Rise poses a substantial concern to communities worldwide. Increased inundation, storm surge, salt water intrusion, and other impacts create challenges which will require considerable planning to address. Recognizing the broad and differing scope of sea level rise issues and the variability of policy options to address them, local planning frameworks are necessary in addition to tools and resources available from state and federal governments. To help assess priorities and preferences on sea level rise planning, a survey of 503 persons affiliated with coastal communities on the East Coast of the United States was conducted in December 2017. This survey studied key aspects locally-driven sea level rise plans, including planning priorities, funding options, methods to resolve conflict, and potential responses. Six key findings address these and other concerns to provide the foundation of a locally driven framework for public officials.Drought, freshwater availability and cultural resilience on Easter Island (SE Pacific) during the Little Ice Agehttps://peerj.com/preprints/276812019-05-312019-05-31Valenti Rull
After decades of human-deterministic explanations for the collapse of the ancient Rapanui culture that inhabited Easter Island (Rapa Nui) before European contact (1722 CE), paleoecological studies developed over the last decade have provided sound evidence of climate changes and their potential socioecological impacts. Especially significant is the occurrence of a century-scale (1570-1720 CE) drought occurred during the Little Ice Age. Freshwater is a critical resource on Easter Island that heavily depends on rain, which maintains the only three permanent surficial freshwater sources on the island: two lakes (Rano Kao and Rano Raraku) and a marsh (Rano Aroi). Under these conditions, the LIA drought could have significantly affected human life; however, the Rapanui society remained healthy, showing remarkable resilience. There are two main hypotheses on how the ancient Rapanui could have obtained freshwater to guarantee its continuity. The intra-island migration hypothesis proposes that Rano Raraku, the cultural center of this culture, dried out and the Rapanui were forced to migrate to Rano Kao, which was likely the only surficial freshwater source during the LIA drought. This shift was accompanied by a profound cultural reorganization. The coastal groundwater hypothesis dismisses the use of lakes and other surficial freshwater sources to maintain the water-stressed Rapanui population and contends that the only routine freshwater sources during the LIA drought were the abundant and widespread coastal seeps fed by fresh/brackish groundwater. The pros and cons of these two hypotheses are discussed on the basis of the available archeological and paleoecological evidence, and it is concluded that in the present state of knowledge, neither can be rejected. Therefore, these two proposals could be complementary, rather than mutually exclusive.
After decades of human-deterministic explanations for the collapse of the ancient Rapanui culture that inhabited Easter Island (Rapa Nui) before European contact (1722 CE), paleoecological studies developed over the last decade have provided sound evidence of climate changes and their potential socioecological impacts. Especially significant is the occurrence of a century-scale (1570-1720 CE) drought occurred during the Little Ice Age. Freshwater is a critical resource on Easter Island that heavily depends on rain, which maintains the only three permanent surficial freshwater sources on the island: two lakes (Rano Kao and Rano Raraku) and a marsh (Rano Aroi). Under these conditions, the LIA drought could have significantly affected human life; however, the Rapanui society remained healthy, showing remarkable resilience. There are two main hypotheses on how the ancient Rapanui could have obtained freshwater to guarantee its continuity. The intra-island migration hypothesis proposes that Rano Raraku, the cultural center of this culture, dried out and the Rapanui were forced to migrate to Rano Kao, which was likely the only surficial freshwater source during the LIA drought. This shift was accompanied by a profound cultural reorganization. The coastal groundwater hypothesis dismisses the use of lakes and other surficial freshwater sources to maintain the water-stressed Rapanui population and contends that the only routine freshwater sources during the LIA drought were the abundant and widespread coastal seeps fed by fresh/brackish groundwater. The pros and cons of these two hypotheses are discussed on the basis of the available archeological and paleoecological evidence, and it is concluded that in the present state of knowledge, neither can be rejected. Therefore, these two proposals could be complementary, rather than mutually exclusive.Energy use in water purification as criterion for selecting drinking water treatment technologieshttps://peerj.com/preprints/277612019-05-272019-05-27Wenfa Ng
Quality of produced water is usually the criterion for selecting between different desalination technologies for turning seawater into drinking water. However, contemporary trend in drinking water treatment sees a convergence between different technologies for the same water quality. Hence, how do different desalination technologies differentiate amongst each other? Awareness of climate change impact as well as price of produced water, energy use per unit of treated water is an oft-used criterion for assessing the effectiveness and efficiency of different desalination technologies. Specifically, comparing multi-effect flash evaporation and reverse osmosis, the latter enjoys a significant energy use advantage given the lack of the need for converting water into the vapor phase as in multi-effect flash evaporation. Thus, energy used in producing drinking water is significantly higher in multi-effect flash evaporation compared to the high pressure process of reverse osmosis. From the operation perspective, reverse osmosis also benefits from its ability to scale linearly in increasing water production capacity through addition of extra membrane modules, which is not the case for multi-effect flash evaporation where a new distillation column is required for significant increase in production capacity. Collectively, with the same quality of water produced by different desalination technologies, comparison between different technologies increasingly relies on the energy use per unit of produced water. Using this criterion, reverse osmosis membrane desalination has a significant advantage relative to multi-effect flash evaporation in energy cost, which translates to a lower price of produced water.
Quality of produced water is usually the criterion for selecting between different desalination technologies for turning seawater into drinking water. However, contemporary trend in drinking water treatment sees a convergence between different technologies for the same water quality. Hence, how do different desalination technologies differentiate amongst each other? Awareness of climate change impact as well as price of produced water, energy use per unit of treated water is an oft-used criterion for assessing the effectiveness and efficiency of different desalination technologies. Specifically, comparing multi-effect flash evaporation and reverse osmosis, the latter enjoys a significant energy use advantage given the lack of the need for converting water into the vapor phase as in multi-effect flash evaporation. Thus, energy used in producing drinking water is significantly higher in multi-effect flash evaporation compared to the high pressure process of reverse osmosis. From the operation perspective, reverse osmosis also benefits from its ability to scale linearly in increasing water production capacity through addition of extra membrane modules, which is not the case for multi-effect flash evaporation where a new distillation column is required for significant increase in production capacity. Collectively, with the same quality of water produced by different desalination technologies, comparison between different technologies increasingly relies on the energy use per unit of produced water. Using this criterion, reverse osmosis membrane desalination has a significant advantage relative to multi-effect flash evaporation in energy cost, which translates to a lower price of produced water.Off-line and on-line optical monitoring of microalgal growthhttps://peerj.com/preprints/277442019-05-192019-05-19Hugo-Enrique Lazcano-HernandezGabriela AguilarGabriela DzulRodrigo PatiñoJavier Arellano-Verdejo
The growth of Chlamydomonas reinhardtii microalgae cultures was successfully monitored, from classic off-line optical techniques (optical density and fluorescence) to on-line analysis of digital images. In this study, it is shown that the chlorophyll fluorescence ratio F685/F740 has a linear correlation with the logarithmic concentration of microalgae. Moreover, with digital images, the biomass concentration was correlated with: the luminosity of the images through an exponential equation, and the length of penetration of a superluminescent blue beam (λ=440 nm), through an inversely proportional function. Outcomes of this study are useful to monitor both research and industrial microalgae cultures.
The growth of Chlamydomonas reinhardtii microalgae cultures was successfully monitored, from classic off-line optical techniques (optical density and fluorescence) to on-line analysis of digital images. In this study, it is shown that the chlorophyll fluorescence ratio F685/F740 has a linear correlation with the logarithmic concentration of microalgae. Moreover, with digital images, the biomass concentration was correlated with: the luminosity of the images through an exponential equation, and the length of penetration of a superluminescent blue beam (λ=440 nm), through an inversely proportional function. Outcomes of this study are useful to monitor both research and industrial microalgae cultures.Detection of pelagic habitats and abundance of skipjack tuna in relation to the environment in the Indian Ocean around Sri Lankahttps://peerj.com/preprints/276632019-05-062019-05-06Thushani Suleka Madhubha ElepathageDanling Tang
Using remote sensing data of sea surface temperature (SST), chlorophyll-a (Chl-a) together with catch data, the pelagic hotspots of Skipjack tuna (SKPJ) were identified. MODIS/Aqua satellite data and the fish catch data were obtained during 2002-2016 period. Empirical cumulative distribution frequency (ECDF) model of satellite-based oceanographic data in relation to skipjack fishing was used for the initial statistical analysis and the results showed that key pelagic habitat corresponded mainly with the 0.4 – 0.7 mg m-3 Chl-a concentration. Chl-a represents the phytoplankton that attracts the food items of SKPJ like zooplankton and nekton The favorable SST range for SKPJ is 26 - 27 0C which provides suitable thermocline and an optimum level of upwelling to circulate nutrients needed for the primary production. The high total catches and CPUEs were found within the months of September to December and the optimum levels of Chl-a, SST also were observed in similar months. Hence, the South-West monsoon season was identified as the best and peak season of SKPJ fisheries. SST and Chl-a are important indicators to detect the habitats of SKPJ and the maps prepared can be used in the future to cost-effectively and efficiently identify and demarcate the biological conservation regions or fisheries zones of SKPJ. According to GAM the 0.3 - 0.6 mg m-3 Chl-a, 28 - 28.5 0C SST in Western and 0.25 - 0.3 mg m-3 Chl-a and 28.5 - 28.80C SST in Eastern were found as highly correlated predictor variables value ranges with SKPJ abundance. The deviances explained in above areas in GAM were 90.8% and 61.4% respectively. The GAM was considered as a robustly dealing method with nonlinear relationships and it can be used to model the fish catch abundance with influencing variables significantly since it could predict the CPUE values greater than 90% similarly to nominal CPUEs in both subregions of the study area.
Using remote sensing data of sea surface temperature (SST), chlorophyll-a (Chl-a) together with catch data, the pelagic hotspots of Skipjack tuna (SKPJ) were identified. MODIS/Aqua satellite data and the fish catch data were obtained during 2002-2016 period. Empirical cumulative distribution frequency (ECDF) model of satellite-based oceanographic data in relation to skipjack fishing was used for the initial statistical analysis and the results showed that key pelagic habitat corresponded mainly with the 0.4 – 0.7 mg m-3 Chl-a concentration. Chl-a represents the phytoplankton that attracts the food items of SKPJ like zooplankton and nekton The favorable SST range for SKPJ is 26 - 27 0C which provides suitable thermocline and an optimum level of upwelling to circulate nutrients needed for the primary production. The high total catches and CPUEs were found within the months of September to December and the optimum levels of Chl-a, SST also were observed in similar months. Hence, the South-West monsoon season was identified as the best and peak season of SKPJ fisheries. SST and Chl-a are important indicators to detect the habitats of SKPJ and the maps prepared can be used in the future to cost-effectively and efficiently identify and demarcate the biological conservation regions or fisheries zones of SKPJ. According to GAM the 0.3 - 0.6 mg m-3 Chl-a, 28 - 28.5 0C SST in Western and 0.25 - 0.3 mg m-3 Chl-a and 28.5 - 28.80C SST in Eastern were found as highly correlated predictor variables value ranges with SKPJ abundance. The deviances explained in above areas in GAM were 90.8% and 61.4% respectively. The GAM was considered as a robustly dealing method with nonlinear relationships and it can be used to model the fish catch abundance with influencing variables significantly since it could predict the CPUE values greater than 90% similarly to nominal CPUEs in both subregions of the study area.Climate change, deforestation patterns, freshwater availability and cultural shifts on prehistoric Easter Island (SE Pacific)https://peerj.com/preprints/276802019-04-242019-04-24Valenti Rull
The remote and isolated Easter Island (Rapa Nui) has been the arena for classic debates on the potential consequences of human overexploitation of natural resources as a microcosmic model for the whole planet. Human-deterministic hypotheses have traditionally been preferred to proposals involving climate changes as drivers of socioecological shifts, especially in relation to the collapse of the ancient Rapanui civilization inhabiting the island before European contact (1722 CE). However, recent paleoecological studies have provided evidence for past climatic shifts, especially droughts, which have stimulated a paradigm shift from deterministic and exclusive views to a more holistic framework that considers both natural and anthropogenic factors as well as their feedbacks and synergies. This paper reviews the latest climatic, ecological and cultural reconstructions of precontact times and evaluates the potential impact of the different drivers on socioecological shifts. Especially noteworthy is the occurrence of some droughts in the last millennium that, coupled with human deforestation, severely affected the access of the prehistoric Rapanui civilization to freshwater but did not compromise the continuity of this ancient culture. Two main hypotheses have been proposed for how the Rapanui bypassed freshwater scarcity. According to the intraisland migration hypothesis, the latest drought recorded (1570-1720 CE) would have led to the abandonment of the former cultural center of the ancient Rapanui civilization (Lake Raraku) to move to Lake Kao, which became the new cultural core. This would have been linked to a profound cultural shift from the moai cult to the Birdman cult. In contrast, the coastal groundwater hypothesis proposes that coastal seeps were the main freshwater source during climatic droughts. These hypotheses are evaluated using the available archaeological and paleoecological evidence, and it is concluded that neither can be rejected; therefore, they could be complementary, rather than exclusive. The continuity of the Rapanui civilization in spite of landscape degradation is a good example of cultural resilience that challenges earlier deterministic explanations and emphasizes human adaptability to changing environments.
The remote and isolated Easter Island (Rapa Nui) has been the arena for classic debates on the potential consequences of human overexploitation of natural resources as a microcosmic model for the whole planet. Human-deterministic hypotheses have traditionally been preferred to proposals involving climate changes as drivers of socioecological shifts, especially in relation to the collapse of the ancient Rapanui civilization inhabiting the island before European contact (1722 CE). However, recent paleoecological studies have provided evidence for past climatic shifts, especially droughts, which have stimulated a paradigm shift from deterministic and exclusive views to a more holistic framework that considers both natural and anthropogenic factors as well as their feedbacks and synergies. This paper reviews the latest climatic, ecological and cultural reconstructions of precontact times and evaluates the potential impact of the different drivers on socioecological shifts. Especially noteworthy is the occurrence of some droughts in the last millennium that, coupled with human deforestation, severely affected the access of the prehistoric Rapanui civilization to freshwater but did not compromise the continuity of this ancient culture. Two main hypotheses have been proposed for how the Rapanui bypassed freshwater scarcity. According to the intraisland migration hypothesis, the latest drought recorded (1570-1720 CE) would have led to the abandonment of the former cultural center of the ancient Rapanui civilization (Lake Raraku) to move to Lake Kao, which became the new cultural core. This would have been linked to a profound cultural shift from the moai cult to the Birdman cult. In contrast, the coastal groundwater hypothesis proposes that coastal seeps were the main freshwater source during climatic droughts. These hypotheses are evaluated using the available archaeological and paleoecological evidence, and it is concluded that neither can be rejected; therefore, they could be complementary, rather than exclusive. The continuity of the Rapanui civilization in spite of landscape degradation is a good example of cultural resilience that challenges earlier deterministic explanations and emphasizes human adaptability to changing environments.Variations in ecosystem service value in response to land use/land cover changes in Central Asia over 1995-2035https://peerj.com/preprints/276452019-04-112019-04-11Jiangyue LiHongxing ChenChi ZhangTao Pan
Acute farmland expansion and rapid urbanization in Central Asia have accelerated land use/land cover changes, which has significant effect onecosystemservice. However, the spatio-temporal changes in ecosystem service values in Central Asia are not well understood. Here, based on land use products with 300-m resolution for the years of 1995, 2005 and 2015 and transfer methodology, we predicted LUCC for 2025 and 2035 using CA-Markov, assessed changes in ecosystem service value in response to LUCC dynamics, and explored the elasticity for the response of ESV to LULC changes. We found significant expansions of cropland and urban and shrinking of water bodies and bare land during 1995-2035. Overall ESVs had an increasing trend from 1995-2035, which was mainly due to the increasing cropland and construction land. The combined valueofecosystemservices of cropland, grassland, water bodies accounted for over 90% of the total ESVs. However, LULC analysis showed that the area of water body reduced by 21.80% from 1995 to 2015 and continued to decrease by 21.14% from 2015 to 2035, indicating that approximately 63.37 billion US$ of ESVs lost in Central Asia. Biodiversity, food production and water regulation were major service functions, accounting for 80.52% of the total ESVs . Our results demonstrated that theeffective land-usepolicies should be made to control farmland expansion and protect water bodies, grassland and forestland for better sustainable ecosystem services.
Acute farmland expansion and rapid urbanization in Central Asia have accelerated land use/land cover changes, which has significant effect onecosystemservice. However, the spatio-temporal changes in ecosystem service values in Central Asia are not well understood. Here, based on land use products with 300-m resolution for the years of 1995, 2005 and 2015 and transfer methodology, we predicted LUCC for 2025 and 2035 using CA-Markov, assessed changes in ecosystem service value in response to LUCC dynamics, and explored the elasticity for the response of ESV to LULC changes. We found significant expansions of cropland and urban and shrinking of water bodies and bare land during 1995-2035. Overall ESVs had an increasing trend from 1995-2035, which was mainly due to the increasing cropland and construction land. The combined valueofecosystemservices of cropland, grassland, water bodies accounted for over 90% of the total ESVs. However, LULC analysis showed that the area of water body reduced by 21.80% from 1995 to 2015 and continued to decrease by 21.14% from 2015 to 2035, indicating that approximately 63.37 billion US$ of ESVs lost in Central Asia. Biodiversity, food production and water regulation were major service functions, accounting for 80.52% of the total ESVs . Our results demonstrated that theeffective land-usepolicies should be made to control farmland expansion and protect water bodies, grassland and forestland for better sustainable ecosystem services.Subsurface biogeochemistry is a missing link between ecology and hydrology in dam-impacted river corridorshttps://peerj.com/preprints/271472018-11-272018-11-27Emily B GrahamJames C StegenMaoyi HuangXingyuan ChenTimothy Scheibe
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.
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.