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Francine H Mejia

I am an aquatic ecologist at the U.S. Geological Survey. I am interested in pairing biological and physical sciences to understand the structure and function of streams and rivers.

My research focuses on aquatic productivity, water quality, and habitat restoration. I am stationed in Usk, Washington and partner with the Kalispel Tribe of Indians to help them monitor and restore culturally important aquatic habitats. These projects range from reach scale monitoring to global analyses.

Professional Experience

  • 2020-Present: Biologist, U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Cascadia Field Station, Seattle, WA

  • 2016-2020: Research Ecologist, Postdoctoral Fellowship, U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Cascadia Field Station, Seattle, WA

  • 2012-2016: Research Assistant, University of Idaho, Moscow, Idaho and Washington State University, Pullman, WA

  • 2010-2012: Senior Environmental Scientist, California Department of Water Resources (DWR), Division of Environmental Water Quality and Estuarine Studies (EWQES), West Sacramento, CA

Education and Certifications

  • Ph.D., Natural Resources, University of Idaho, Moscow, ID (2016)

  • M.S., Fish and Wildlife Management, State University of New York, Syracuse, NY (1997)

  • B.S., Biology, Brooklyn College, Brooklyn, NY (1994)

Affiliations and Memberships*

  • American Geophysical Union

  • American Fisheries Society

  • Society for Freshwater Science

Abstracts and Presentations

  • Mejia, F.H., V. Ouellet. 2021. Effects of global change on aquatic biocenosis- Lessons learned from cold-water refuges- The Integrative Science (I.S). Rivers Conference (virtual): June 21, 2021

  • Mejia F.H., C.E. Torgersen, E.K. Berntsen, T. Andersen, W. Love. 2020. Closing data gaps with citizen science to describe thermal diversity in a dam-influenced river. River Restoration Northwest Stream Restoration Symposium, February 4-6 in Stevenson, Washington. Poster presentation

  • Mejia, F.H. 2018, 2019, 2020 and 2021. Understanding Streams in a Watershed Context. Idaho Fish and Game Master Naturalist Program, Pend Oreille Chapter. Sandpoint, Idaho, Oral Presentation

  • Mejia F.H., C.E. Torgersen, E.K. Berntsen, J.R. Maroney, J.M. Connor, A.H. Fullerton, J.L. Ebersole, M.S. Lorang. 2020. Longitudinal, Lateral, Vertical, and Temporal Thermal Heterogeneity in a Large Impounded River: Implications for Cold-Water Refuges. Pacific Northwest Chapter of the Society for Freshwater Science Virtual meeting, November 18- 19.

  • Mejia F.H., C.E. Torgersen, E.K. Berntsen, T. Andersen, P.R. Kaufmann, and M.S. Lorang. Characterizing spatiotemporal variability in water temperature and habitat to inform restoration for cold-water fishes. 2020. 30th Annual Idaho Water Quality Workshop, February 11-13 in Boise, Idaho. Oral presentation.

Science and Products

link
Updated classifications of flow permanence on streams in the Colville National Forest

Updated classifications of flow permanence on streams in the Colville National Forest

The Issue: Streamflow permanence refers to the probability that a stream will lose surface flow (become a dry channel), as well as the timing, duration, and frequency of drying. Patterns of streamflow permanence drive important decisions regarding forest management and other land uses. The Colville National Forest Land and Resource Management Plan (2019), for example, specifies riparian management...
By
Forest and Rangeland Ecosystem Science Center, Washington Water Science Center
link

Updated classifications of flow permanence on streams in the Colville National Forest

The Issue: Streamflow permanence refers to the probability that a stream will lose surface flow (become a dry channel), as well as the timing, duration, and frequency of drying. Patterns of streamflow permanence drive important decisions regarding forest management and other land uses. The Colville National Forest Land and Resource Management Plan (2019), for example, specifies riparian management...
Learn More

If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.

FLOwPER Database: StreamFLOw PERmanence field observations, Jan 2021 - Dec 2021

IMPORTANT NOTE: This dataset includes spatial locations where streamflow permanence observations (continuous flow, discontinuous flow, and dry) were recorded using the FLOwPER (FLOw PERmanence) field survey available in the Survey 123. Additional information to describe the field conditions are included as part of the survey. Field observations in the FLOwPER Database have not been processed for q
By
Forest and Rangeland Ecosystem Science Center

Distribution, frequency, and global extent of hypoxia in rivers

To assess the distribution, frequency, and global extent of riverine hypoxia, we compiled 118 million paired dissolved oxygen (DO) and water temperature measurements from 125,158 unique locations in rivers in 93 countries and territories across the globe. The dataset also includes site characteristics derived from StreamCat, the National Hydrography and HydroAtlas datasets and proximal land cover
By
Forest and Rangeland Ecosystem Science Center

Fishes of the Harney Basin revisited: A contemporary assessment of the distribution of fish fauna throughout the Harney Basin from 1990 to 2019 (ver. 2.0, April 2022)

We compiled electrofishing and habitat data sampled from 1990 to 2019 in the Harney Basin by the US Geological Survey (USGS), Oregon Department of Fish and Wildlife (ODFW) and the High Desert Partnership (HDP) to describe native and non-native fish distributions and their habitat associations. USGS collected eDNA data in 2019 to refine the known distributions of common carp (Cyprinus carpio). Site
By
Forest and Rangeland Ecosystem Science Center, Pacific Northwest Environmental DNA Laboratory

Spatial and temporal variability of summer water temperature at cool-water areas in the Pend Oreille River, Washington (ver. 2.0, March 2024)

Water temperature data were collected in summer 2021 and 2023 at the confluences of Indian Creek and Duncan Springs in the Pend Oreille River. Continuously recording temperature loggers were deployed near the substratum and near the surface of the water column.
By
Forest and Rangeland Ecosystem Science Center

Airborne thermal infrared remote sensing of summer water temperature in the Middle Fork John Day River (Oregon) in 1994-2003

This data release combines seven airborne thermal infrared (TIR) remote sensing data sets of stream temperature collected along the mainstem of the Middle Fork John Day River (MFJD) in Oregon from 1994 to 2003. Years 1994, 1995, 1996, 1998, and 2002 have single datasets. Year 2003 has two data sets. Most of the TIR data covered the upstream half of the MFJD mainstem between river km 50 and 110, wh
By
Forest and Rangeland Ecosystem Science Center

Water temperature data from the Priest River, Idaho, 2018-2019

Water temperature data were collected in summer 2018 and 2019. Temperature data loggers were deployed in tributary confluences and the mainstem of the lower Priest River between Priest Lake Outlet Dam and the confluence with the Pend Oreille River. Data loggers were checked every 2 to 3 weeks throughout the summer. Data for Lagrangian longitudinal thermal profiles were obtained on August 21, 2018
By
Forest and Rangeland Ecosystem Science Center

Water temperature data from the Pend Oreille River, Washington and Idaho, 2016-2018

The data were collected summer, 2016, 2017, and 2018. Continuous temperature loggers were deployed along the Pend Oreille River between Albeni Falls Dam and the Box Canyon Dam. Loggers were checked every 1-2 weeks throughout the summer.
By
Forest and Rangeland Ecosystem Science Center
Pend Oreille River in winter
Pend Oreille River in winter
Pend Oreille River in winter
Pend Oreille River in winter

Pend Oreille River in winter

Pend Oreille River in winter

The Kalispel Tribe in northeastern Washington is located along the Pend Oreille River, home to culturally important, cold-water fish, such as bull trout and cutthroat trout.

By
Ecosystems, Forest and Rangeland Ecosystem Science Center
Pend Oreille River in winter

Pend Oreille River in winter

Pend Oreille River in winter

The Kalispel Tribe in northeastern Washington is located along the Pend Oreille River, home to culturally important, cold-water fish, such as bull trout and cutthroat trout.

By
Ecosystems, Forest and Rangeland Ecosystem Science Center

If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.

Fishes of Harney Basin revisited: An assessment of the distribution of native and nonnative fishes over a half century

The Harney Basin is Oregon's largest internally draining basin and contains a unique native fish assemblage. The first and only comprehensive study of the origin and distribution of Harney Basin fishes occurred in 1971. Here, we update this study and identify potential threats to the basin's native fishes a half century later. Our assessment documents that all species of native fishes are still pr
Authors
Matthew Laramie, Jason B. Dunham, Francine H. Mejia, Emily Dawn Heaston, Peter A Bisson
By
Ecosystems Mission Area, Forest and Rangeland Ecosystem Science Center

Closing the gap between science and management of cold-water refuges in rivers and streams

Human activities and climate change threaten coldwater organisms in freshwater ecosystems by causing rivers and streams to warm, increasing the intensity and frequency of warm temperature events, and reducing thermal heterogeneity. Cold-water refuges are discrete patches of relatively cool water that are used by coldwater organisms for thermal relief and short-term survival. Globally, cohesive man
Authors
Francine H. Mejia, Valerie Ouellet, Martin Briggs, Stephanie M. Carlson, Rose Casas-Mulet, Mollie Chapman, Matthias J. Collins, Stephen J. Dugdale, Joseph L. Ebersole, Danielle M. Frechette, Aimee H. Fullerton, Carol-Anne Gillis, Zachary Johnson, Christa Kelleher, Barret L. Kurylyk, Rebecca Lave, Benjamin Letcher, Knut M. Myrvold, Tracie-Lynn Nadeau, Helen Neville, Herve Piégay, Kathryn E. Smith, Diego Tonolla, Christian E. Torgersen
By
Ecosystems Mission Area, Forest and Rangeland Ecosystem Science Center, Eastern Ecological Science Center

Extent, patterns, and drivers of hypoxia in the world's streams and rivers

Hypoxia in coastal waters and lakes is widely recognized as a detrimental environmental issue, yet we lack a comparable understanding of hypoxia in rivers. We investigated controls on hypoxia using 118 million paired observations of dissolved oxygen (DO) concentration and water temperature in over 125,000 locations in rivers from 93 countries. We found hypoxia (DO < 2 mg L−1) in 12.6% of all river
Authors
Joanna R Blaszczak, Lauren E Koenig, Francine H. Mejia, Alice M. Carter, Lluis Gómez-Gener, Christoper L Dutton, Nancy B. Grimm, Judson Harvey, Ashley M. Helton, Matthew J. Cohen
By
Ecosystems Mission Area, Water Resources Mission Area, Land Management Research Program, Forest and Rangeland Ecosystem Science Center

Keeping an eye on water quality from the sky

You can learn a lot about rivers, lakes, estuaries, and oceans by looking down at them from the sky. Scientists use a technique called remote sensing to measure the amount of light or heat energy reflected and emitted from the Earth. Sensors can be on satellites or mounted on airplanes, helicopters, or drones. Scientists use this information to map the quality of water in the San Francisco Bay-Del
Authors
Francine H. Mejia, Christian E. Torgersen, Cédric G Fichot
By
Ecosystems Mission Area, Forest and Rangeland Ecosystem Science Center

Integrating regional and local monitoring data and assessment tools to evaluate habitat conditions and inform river restoration

RRestoring degraded rivers requires initial assessment of the fluvial landscape to identify stressors and riverine features that can be enhanced. We associated local-scale river habitat data collected using standardized national monitoring tools with modeled regional water temperature and flow data on mid-sized northwest U.S. rivers (30–60 m wide). We grouped these rivers according to quartiles of
Authors
Francine H. Mejia, Jason M Connor, Phil R Kaufmann, Christian E. Torgersen, Eric K Berntsen, Todd Andersen
By
Ecosystems Mission Area, Forest and Rangeland Ecosystem Science Center

Aquatic ecosystem metabolism as a tool in environmental management

Recent advances in high-frequency environmental sensing and statistical approaches have greatly expanded the breadth of knowledge regarding aquatic ecosystem metabolism - the measurement and interpretation of gross primary productivity (GPP) and ecosystem respiration (ER). Aquatic scientists are poised to take advantage of widely available datasets and freely-available modeling tools to apply func
Authors
Kathi Jo Jankowski, Francine H. Mejia, Joanna Blaszczak, Gordon W. Holtgrieve
By
Ecosystems Mission Area, Forest and Rangeland Ecosystem Science Center, Upper Midwest Environmental Sciences Center

Longitudinal, lateral, vertical, and temporal thermal heterogeneity in a large impounded river: Implications for cold-water refuges

Dam operations can affect mixing of the water column, thereby influencing thermal heterogeneity spatially and temporally. This occurs by restricting or eliminating connectivity in longitudinal, lateral, vertical, and temporal dimensions. We examined thermal heterogeneity across space and time and identified potential cold-water refuges for salmonids in a large impounded river in inland northwester
Authors
Francine H. Mejia, Christian E. Torgersen, Eric K Berntsen, Joseph R Maroney, J M Connor, Aimee H. Fullerton, Joseph L. Ebersole, Mark L Lorang
By
Ecosystems Mission Area, Forest and Rangeland Ecosystem Science Center

Stream metabolism increases with drainage area and peaks asynchronously across a stream network

Quantifying the spatial and temporal dynamics of stream metabolism across stream networks is key to understanding carbon cycling and stream food web ecology. To better understand intra-annual temporal patterns of gross primary production (GPP) and ecosystem respiration (ER) and their variability across space, we continuously measured dissolved oxygen and modeled stream metabolism for an entire yea
Authors
Francine H. Mejia, Alexander K. Fremier, Joseph R. Benjamin, J. Ryan Bellmore, Adrianne Z. Grimm, Grace A. Watson, Michael Newsom
By
Ecosystems Mission Area, Forest and Rangeland Ecosystem Science Center

The response of stream periphyton to Pacific salmon: using a model to understand the role of environmental context

1. In stream ecosystems, Pacific salmon deliver subsidies of marine-derived nutrients and disturb the stream bed during spawning. The net effect of this nutrient subsidy and physical disturbance on biological communities can be hard to predict and is likely to be mediated by environmental conditions. For periphyton, empirical studies have revealed that the magnitude and direction of the response t
Authors
J. Ryan Bellmore, Alexander K. Fremier, Francine Mejia, Michael Newsom
By
Ecosystems Mission Area, Western Fisheries Research Center, Columbia River Research Laboratory (CRRL)

Relation between species assemblages of fishes and water quality in salt ponds and sloughs in South San Francisco Bay

This study was conducted to characterize fishery resources inhabiting salt-evaporation ponds and sloughs in South San Francisco Bay, and to identify key environmental variables that influence distribution of fishes. The ponds, which were originally constructed and operated for commercial production of salt, have undergone preliminary modifications (installation of culverts, gates, and other water-
Authors
F. Mejia, M. K. Saiki, John Y. Takekawa
By
Ecosystems Mission Area, Water Resources Mission Area, California Water Science Center, Western Fisheries Research Center

Smallmouth bass and largemouth bass predation on juvenile Chinook salmon and other salmonids in the Lake Washington basin

We assessed the impact of predation by smallmouth bass Micropterus dolomieu and largemouth bass M. salmoides on juveniles of federally listed Chinook salmon Oncorhynchus tshawytscha and other anadromous salmonid populations in the Lake Washington system. Bass were collected with boat electrofishing equipment in the south end of Lake Washington (February-June) and the Lake Washington Ship Canal (LW
Authors
R.A. Tabor, B.A. Footen, K.L. Fresh, M.T. Celedonia, F. Mejia, D.L. Low, L. Park

Non-USGS Publications**

Mejia F.H., C.V. Baxter, E.K. Berntsen and A.K. Fremier. 2016. Linking groundwater - surface water exchange to food production and salmonid growth. Canadian Journal of Fisheries and Aquatic Sciences. 73:1650-1660.
Mejia F.H. 2016. Understanding Variability of Stream Productivity at Different Scales and Consequences for Aquatic Food Webs. PhD Dissertation, University of Idaho, Moscow, Idaho. 135 pp.
Sommer, T.R., and F.H. Mejia. 2013, A Place to Call Home: A Synthesis of Delta Smelt Habitat in the Upper San Francisco Estuary, San Francisco Estuary and Watershed Science 11(2), 27 p.
Sommer, T.R., F.H. Mejia, K. Hieb, R. Baxter, E. J. Loboschefsky and F.J. Loge. 2011. Long-term shifts in the lateral distribution of age-0 striped bass Morone saxatilis in the San Francisco estuary. Transactions of the American Fisheries Society. 140: 1451-1459
Sommer, T.R., F.H. Mejia, M.L. Nobriga, F. Feyrer; and L. Grimaldo. 2011. The Spawning Migration of Delta Smelt in the Upper San Francisco Estuary. San Francisco Estuary and Watershed Science, 9(2).
Saiki, M.K. and F.H. Mejia. 2009. Fish-Use of the Alviso Island Ponds and Adjacent Waters in South San Francisco Bay Following the Breaching of Earthen Levees. California Fish and Game Journal (95):1-15.
Mejia, F.H. Dominant Lake Erie Prey Fish and their Consumption of Invertebrate Prey: An Energetics Modeling Analysis. M.S. Thesis, SUNY College of Environmental Science and Forestry, December 1997.

**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

Closing the Gap Between Science and Management of Cold-Water Refuges in Rivers and Streams

Closing the Gap Between Science and Management of Cold-Water Refuges in Rivers and Streams

An international group of scientists, regulators, and managers met to discuss management of cold-water refuges and species that need cool water to...

Read Article
Thermal Heterogeneity in a Large Impounded River: Implications for Cold-Water Refuges

Thermal Heterogeneity in a Large Impounded River: Implications for Cold-Water Refuges

Dam operations can influence spatial and temporal thermal heterogeneity in rivers, yet quantity and distribution of cold-water refuges for salmonids...

Read Article

Science and Products

link
Updated classifications of flow permanence on streams in the Colville National Forest

Updated classifications of flow permanence on streams in the Colville National Forest

The Issue: Streamflow permanence refers to the probability that a stream will lose surface flow (become a dry channel), as well as the timing, duration, and frequency of drying. Patterns of streamflow permanence drive important decisions regarding forest management and other land uses. The Colville National Forest Land and Resource Management Plan (2019), for example, specifies riparian management...
By
Forest and Rangeland Ecosystem Science Center, Washington Water Science Center
link

Updated classifications of flow permanence on streams in the Colville National Forest

The Issue: Streamflow permanence refers to the probability that a stream will lose surface flow (become a dry channel), as well as the timing, duration, and frequency of drying. Patterns of streamflow permanence drive important decisions regarding forest management and other land uses. The Colville National Forest Land and Resource Management Plan (2019), for example, specifies riparian management...
Learn More

If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.

FLOwPER Database: StreamFLOw PERmanence field observations, Jan 2021 - Dec 2021

IMPORTANT NOTE: This dataset includes spatial locations where streamflow permanence observations (continuous flow, discontinuous flow, and dry) were recorded using the FLOwPER (FLOw PERmanence) field survey available in the Survey 123. Additional information to describe the field conditions are included as part of the survey. Field observations in the FLOwPER Database have not been processed for q
By
Forest and Rangeland Ecosystem Science Center

Distribution, frequency, and global extent of hypoxia in rivers

To assess the distribution, frequency, and global extent of riverine hypoxia, we compiled 118 million paired dissolved oxygen (DO) and water temperature measurements from 125,158 unique locations in rivers in 93 countries and territories across the globe. The dataset also includes site characteristics derived from StreamCat, the National Hydrography and HydroAtlas datasets and proximal land cover
By
Forest and Rangeland Ecosystem Science Center

Fishes of the Harney Basin revisited: A contemporary assessment of the distribution of fish fauna throughout the Harney Basin from 1990 to 2019 (ver. 2.0, April 2022)

We compiled electrofishing and habitat data sampled from 1990 to 2019 in the Harney Basin by the US Geological Survey (USGS), Oregon Department of Fish and Wildlife (ODFW) and the High Desert Partnership (HDP) to describe native and non-native fish distributions and their habitat associations. USGS collected eDNA data in 2019 to refine the known distributions of common carp (Cyprinus carpio). Site
By
Forest and Rangeland Ecosystem Science Center, Pacific Northwest Environmental DNA Laboratory

Spatial and temporal variability of summer water temperature at cool-water areas in the Pend Oreille River, Washington (ver. 2.0, March 2024)

Water temperature data were collected in summer 2021 and 2023 at the confluences of Indian Creek and Duncan Springs in the Pend Oreille River. Continuously recording temperature loggers were deployed near the substratum and near the surface of the water column.
By
Forest and Rangeland Ecosystem Science Center

Airborne thermal infrared remote sensing of summer water temperature in the Middle Fork John Day River (Oregon) in 1994-2003

This data release combines seven airborne thermal infrared (TIR) remote sensing data sets of stream temperature collected along the mainstem of the Middle Fork John Day River (MFJD) in Oregon from 1994 to 2003. Years 1994, 1995, 1996, 1998, and 2002 have single datasets. Year 2003 has two data sets. Most of the TIR data covered the upstream half of the MFJD mainstem between river km 50 and 110, wh
By
Forest and Rangeland Ecosystem Science Center

Water temperature data from the Priest River, Idaho, 2018-2019

Water temperature data were collected in summer 2018 and 2019. Temperature data loggers were deployed in tributary confluences and the mainstem of the lower Priest River between Priest Lake Outlet Dam and the confluence with the Pend Oreille River. Data loggers were checked every 2 to 3 weeks throughout the summer. Data for Lagrangian longitudinal thermal profiles were obtained on August 21, 2018
By
Forest and Rangeland Ecosystem Science Center

Water temperature data from the Pend Oreille River, Washington and Idaho, 2016-2018

The data were collected summer, 2016, 2017, and 2018. Continuous temperature loggers were deployed along the Pend Oreille River between Albeni Falls Dam and the Box Canyon Dam. Loggers were checked every 1-2 weeks throughout the summer.
By
Forest and Rangeland Ecosystem Science Center
Pend Oreille River in winter
Pend Oreille River in winter
Pend Oreille River in winter
Pend Oreille River in winter

Pend Oreille River in winter

Pend Oreille River in winter

The Kalispel Tribe in northeastern Washington is located along the Pend Oreille River, home to culturally important, cold-water fish, such as bull trout and cutthroat trout.

By
Ecosystems, Forest and Rangeland Ecosystem Science Center
Pend Oreille River in winter

Pend Oreille River in winter

Pend Oreille River in winter

The Kalispel Tribe in northeastern Washington is located along the Pend Oreille River, home to culturally important, cold-water fish, such as bull trout and cutthroat trout.

By
Ecosystems, Forest and Rangeland Ecosystem Science Center

If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.

Fishes of Harney Basin revisited: An assessment of the distribution of native and nonnative fishes over a half century

The Harney Basin is Oregon's largest internally draining basin and contains a unique native fish assemblage. The first and only comprehensive study of the origin and distribution of Harney Basin fishes occurred in 1971. Here, we update this study and identify potential threats to the basin's native fishes a half century later. Our assessment documents that all species of native fishes are still pr
Authors
Matthew Laramie, Jason B. Dunham, Francine H. Mejia, Emily Dawn Heaston, Peter A Bisson
By
Ecosystems Mission Area, Forest and Rangeland Ecosystem Science Center

Closing the gap between science and management of cold-water refuges in rivers and streams

Human activities and climate change threaten coldwater organisms in freshwater ecosystems by causing rivers and streams to warm, increasing the intensity and frequency of warm temperature events, and reducing thermal heterogeneity. Cold-water refuges are discrete patches of relatively cool water that are used by coldwater organisms for thermal relief and short-term survival. Globally, cohesive man
Authors
Francine H. Mejia, Valerie Ouellet, Martin Briggs, Stephanie M. Carlson, Rose Casas-Mulet, Mollie Chapman, Matthias J. Collins, Stephen J. Dugdale, Joseph L. Ebersole, Danielle M. Frechette, Aimee H. Fullerton, Carol-Anne Gillis, Zachary Johnson, Christa Kelleher, Barret L. Kurylyk, Rebecca Lave, Benjamin Letcher, Knut M. Myrvold, Tracie-Lynn Nadeau, Helen Neville, Herve Piégay, Kathryn E. Smith, Diego Tonolla, Christian E. Torgersen
By
Ecosystems Mission Area, Forest and Rangeland Ecosystem Science Center, Eastern Ecological Science Center

Extent, patterns, and drivers of hypoxia in the world's streams and rivers

Hypoxia in coastal waters and lakes is widely recognized as a detrimental environmental issue, yet we lack a comparable understanding of hypoxia in rivers. We investigated controls on hypoxia using 118 million paired observations of dissolved oxygen (DO) concentration and water temperature in over 125,000 locations in rivers from 93 countries. We found hypoxia (DO < 2 mg L−1) in 12.6% of all river
Authors
Joanna R Blaszczak, Lauren E Koenig, Francine H. Mejia, Alice M. Carter, Lluis Gómez-Gener, Christoper L Dutton, Nancy B. Grimm, Judson Harvey, Ashley M. Helton, Matthew J. Cohen
By
Ecosystems Mission Area, Water Resources Mission Area, Land Management Research Program, Forest and Rangeland Ecosystem Science Center

Keeping an eye on water quality from the sky

You can learn a lot about rivers, lakes, estuaries, and oceans by looking down at them from the sky. Scientists use a technique called remote sensing to measure the amount of light or heat energy reflected and emitted from the Earth. Sensors can be on satellites or mounted on airplanes, helicopters, or drones. Scientists use this information to map the quality of water in the San Francisco Bay-Del
Authors
Francine H. Mejia, Christian E. Torgersen, Cédric G Fichot
By
Ecosystems Mission Area, Forest and Rangeland Ecosystem Science Center

Integrating regional and local monitoring data and assessment tools to evaluate habitat conditions and inform river restoration

RRestoring degraded rivers requires initial assessment of the fluvial landscape to identify stressors and riverine features that can be enhanced. We associated local-scale river habitat data collected using standardized national monitoring tools with modeled regional water temperature and flow data on mid-sized northwest U.S. rivers (30–60 m wide). We grouped these rivers according to quartiles of
Authors
Francine H. Mejia, Jason M Connor, Phil R Kaufmann, Christian E. Torgersen, Eric K Berntsen, Todd Andersen
By
Ecosystems Mission Area, Forest and Rangeland Ecosystem Science Center

Aquatic ecosystem metabolism as a tool in environmental management

Recent advances in high-frequency environmental sensing and statistical approaches have greatly expanded the breadth of knowledge regarding aquatic ecosystem metabolism - the measurement and interpretation of gross primary productivity (GPP) and ecosystem respiration (ER). Aquatic scientists are poised to take advantage of widely available datasets and freely-available modeling tools to apply func
Authors
Kathi Jo Jankowski, Francine H. Mejia, Joanna Blaszczak, Gordon W. Holtgrieve
By
Ecosystems Mission Area, Forest and Rangeland Ecosystem Science Center, Upper Midwest Environmental Sciences Center

Longitudinal, lateral, vertical, and temporal thermal heterogeneity in a large impounded river: Implications for cold-water refuges

Dam operations can affect mixing of the water column, thereby influencing thermal heterogeneity spatially and temporally. This occurs by restricting or eliminating connectivity in longitudinal, lateral, vertical, and temporal dimensions. We examined thermal heterogeneity across space and time and identified potential cold-water refuges for salmonids in a large impounded river in inland northwester
Authors
Francine H. Mejia, Christian E. Torgersen, Eric K Berntsen, Joseph R Maroney, J M Connor, Aimee H. Fullerton, Joseph L. Ebersole, Mark L Lorang
By
Ecosystems Mission Area, Forest and Rangeland Ecosystem Science Center

Stream metabolism increases with drainage area and peaks asynchronously across a stream network

Quantifying the spatial and temporal dynamics of stream metabolism across stream networks is key to understanding carbon cycling and stream food web ecology. To better understand intra-annual temporal patterns of gross primary production (GPP) and ecosystem respiration (ER) and their variability across space, we continuously measured dissolved oxygen and modeled stream metabolism for an entire yea
Authors
Francine H. Mejia, Alexander K. Fremier, Joseph R. Benjamin, J. Ryan Bellmore, Adrianne Z. Grimm, Grace A. Watson, Michael Newsom
By
Ecosystems Mission Area, Forest and Rangeland Ecosystem Science Center

The response of stream periphyton to Pacific salmon: using a model to understand the role of environmental context

1. In stream ecosystems, Pacific salmon deliver subsidies of marine-derived nutrients and disturb the stream bed during spawning. The net effect of this nutrient subsidy and physical disturbance on biological communities can be hard to predict and is likely to be mediated by environmental conditions. For periphyton, empirical studies have revealed that the magnitude and direction of the response t
Authors
J. Ryan Bellmore, Alexander K. Fremier, Francine Mejia, Michael Newsom
By
Ecosystems Mission Area, Western Fisheries Research Center, Columbia River Research Laboratory (CRRL)

Relation between species assemblages of fishes and water quality in salt ponds and sloughs in South San Francisco Bay

This study was conducted to characterize fishery resources inhabiting salt-evaporation ponds and sloughs in South San Francisco Bay, and to identify key environmental variables that influence distribution of fishes. The ponds, which were originally constructed and operated for commercial production of salt, have undergone preliminary modifications (installation of culverts, gates, and other water-
Authors
F. Mejia, M. K. Saiki, John Y. Takekawa
By
Ecosystems Mission Area, Water Resources Mission Area, California Water Science Center, Western Fisheries Research Center

Smallmouth bass and largemouth bass predation on juvenile Chinook salmon and other salmonids in the Lake Washington basin

We assessed the impact of predation by smallmouth bass Micropterus dolomieu and largemouth bass M. salmoides on juveniles of federally listed Chinook salmon Oncorhynchus tshawytscha and other anadromous salmonid populations in the Lake Washington system. Bass were collected with boat electrofishing equipment in the south end of Lake Washington (February-June) and the Lake Washington Ship Canal (LW
Authors
R.A. Tabor, B.A. Footen, K.L. Fresh, M.T. Celedonia, F. Mejia, D.L. Low, L. Park

Non-USGS Publications**

Mejia F.H., C.V. Baxter, E.K. Berntsen and A.K. Fremier. 2016. Linking groundwater - surface water exchange to food production and salmonid growth. Canadian Journal of Fisheries and Aquatic Sciences. 73:1650-1660.
Mejia F.H. 2016. Understanding Variability of Stream Productivity at Different Scales and Consequences for Aquatic Food Webs. PhD Dissertation, University of Idaho, Moscow, Idaho. 135 pp.
Sommer, T.R., and F.H. Mejia. 2013, A Place to Call Home: A Synthesis of Delta Smelt Habitat in the Upper San Francisco Estuary, San Francisco Estuary and Watershed Science 11(2), 27 p.
Sommer, T.R., F.H. Mejia, K. Hieb, R. Baxter, E. J. Loboschefsky and F.J. Loge. 2011. Long-term shifts in the lateral distribution of age-0 striped bass Morone saxatilis in the San Francisco estuary. Transactions of the American Fisheries Society. 140: 1451-1459
Sommer, T.R., F.H. Mejia, M.L. Nobriga, F. Feyrer; and L. Grimaldo. 2011. The Spawning Migration of Delta Smelt in the Upper San Francisco Estuary. San Francisco Estuary and Watershed Science, 9(2).
Saiki, M.K. and F.H. Mejia. 2009. Fish-Use of the Alviso Island Ponds and Adjacent Waters in South San Francisco Bay Following the Breaching of Earthen Levees. California Fish and Game Journal (95):1-15.
Mejia, F.H. Dominant Lake Erie Prey Fish and their Consumption of Invertebrate Prey: An Energetics Modeling Analysis. M.S. Thesis, SUNY College of Environmental Science and Forestry, December 1997.

**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

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*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government

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