Lake in Wrangell St. Elias National Park. This is part of a study examining mercury in lake food webs.
Mercury concentrations in fish likely reflect different energy sources in lake food webs. Species, populations, or individuals may contain higher and variable concentrations of mercury, which may relate directly to prey mercury content, diets of fish, and fish foraging strategies.
Return to Ecosystems >> Fish and Aquatic Ecology
Sources/Usage: Public Domain. View Media Details
Mercury (Hg) is a toxic contaminant that threatens the health of aquatic ecosystems and species by affecting neurological, cardiovascular, endocrine, renal, and reproductive function. Particularly concerning, Hg accumulates over time in fish tissue, generally increasing with size and age, especially in long-lived piscivorous species like lake trout (Salvelinus namaycush). When contaminant levels reach specific thresholds (e.g., Environmental Protection Agency [EPA] benchmarks for health and toxicity), fish consumption can be harmful to people and wildlife, and safety advisories can be issued for lakes or species. Hg concentrations measured in resident lake fish at several of Alaska’s National Parks were among the highest measured in the western United States, exceeding both ecological (>90 ng/g wet weight) and human health benchmarks (>300 ng/g wet weight). Yet fish Hg concentrations varied widely across and within park lakes and among individuals in the same lake. Because diet is the main Hg accumulation pathway in fish, we aim to investigate the dietary pathways and Hg bioaccumulation from prey to predator.
The movement of Hg through lake food webs is related to within-lake biological processes like Hg methylation rate, biogeochemical characteristics, and energy transfer between trophic levels. By sampling a top predator (lake trout), associated prey species, and primary producers we can trace Hg through lake food webs and determine whether specific energy pathways promote bioaccumulation. In sampling across several National Parks, information will be gathered on limnological, morphological, and biogeochemical characteristics of a diverse set of lakes, providing a baseline of information to study Hg pathways in additional parks, in food webs with different species, or in the future.
Learn more about a sampling effort conducted with the U.S. Geological Survey and National Park Service in Lake Clark, Wrangell-St. Elias, and Gates of the Arctic national parks and preserves and Noatak National Preserve. National Park Article: Tracing Mercury through Lake Food Webs
Sources/Usage: Public Domain. View Media Details
Fish and Aquatic Ecology
Fish and aquatic habitats in Alaska support important commercial, sport, and subsistence fisheries and provide forage fish that support wildlife populations. The USGS Alaska Science Center conducts interdisciplinary research to inform local, state, federal, and international policy makers regarding conservation of fish, aquatic species, and their habitats. We work collaboratively with hydrologists...
Images related to this project below.
Lake in Wrangell St. Elias National Park
Lake in Wrangell St. Elias National Park. This is part of a study examining mercury in lake food webs.
Round whitefish in Wrangell St. Elias National Park
Round whitefish in Wrangell St. Elias National Park. Round whitefish (Prosopium cylindraceum) were collected as part of a study examining mercury in lake food webs.
Round whitefish in Wrangell St. Elias National Park. Round whitefish (Prosopium cylindraceum) were collected as part of a study examining mercury in lake food webs.
Longnose sucker in Wrangell St. Elias National Park
Longnose sucker in Wrangell St. Elias National Park. Longnose suckers (Catostomus catostomus) were collected as part of a study examining mercury in lake food webs.
Longnose sucker in Wrangell St. Elias National Park. Longnose suckers (Catostomus catostomus) were collected as part of a study examining mercury in lake food webs.
Burbot in Wrangell St. Elias National Park
Burbot in Wrangell St. Elias National Park. Burbot (Lota lota) were collected as part of a study examining mercury in lake food webs.
Burbot in Wrangell St. Elias National Park. Burbot (Lota lota) were collected as part of a study examining mercury in lake food webs.
Fishing for lake trout in Wrangell St. Elias National Park
Fishing for lake trout (Salvelinus namaycush) in Wrangell St. Elias National Park. Sam Graf (NPS – LACL) and Ashley Stanek (USGS – ASC) angle for lake trout (Salvelinus namaycush) in Wrangell St. Elias National Park as part of a study examining mercury in lake food webs.
Fishing for lake trout (Salvelinus namaycush) in Wrangell St. Elias National Park. Sam Graf (NPS – LACL) and Ashley Stanek (USGS – ASC) angle for lake trout (Salvelinus namaycush) in Wrangell St. Elias National Park as part of a study examining mercury in lake food webs.
Fyke net in Wrangell St. Elias National Park
Fyke net in Wrangell St. Elias National Park. Sam Graf (NPS – LACL) adjusts a fyke net installed in a lake in Wrangell St. Elias National Park. Fyke nets are used to non-lethally capture fish.
Fyke net in Wrangell St. Elias National Park. Sam Graf (NPS – LACL) adjusts a fyke net installed in a lake in Wrangell St. Elias National Park. Fyke nets are used to non-lethally capture fish.
Arctic grayling in Wrangell St. Elias National Park
Arctic grayling (Thymallus arcticus) in Wrangell St. Elias National Park. Arctic grayling were collected as part of a study examining mercury in lake food webs.
Arctic grayling (Thymallus arcticus) in Wrangell St. Elias National Park. Arctic grayling were collected as part of a study examining mercury in lake food webs.
Lake trout sampling
Lake trout with stomach contents in Wrangell St. Elias National Park. Dorsal muscle collection and stomach content analysis are used to evaluate biomagnification of mercury in Lake trout (Salvelinus namaycush). Stomach contents visible below the fish consist primarily of slimy sculpin (Cottus cognatus).
Lake trout with stomach contents in Wrangell St. Elias National Park. Dorsal muscle collection and stomach content analysis are used to evaluate biomagnification of mercury in Lake trout (Salvelinus namaycush). Stomach contents visible below the fish consist primarily of slimy sculpin (Cottus cognatus).
Collecting benthic macroinvertebrates in Wrangell St. Elias National Park
Sam Graf (NPS – LACL) collects benthic macroinvertebrates using an Eckman grab in Wrangell St. Elias National Park as part of a study examining mercury in lake food webs.
Sam Graf (NPS – LACL) collects benthic macroinvertebrates using an Eckman grab in Wrangell St. Elias National Park as part of a study examining mercury in lake food webs.
Collecting benthic macroinvertebrates
Collecting benthic macroinvertebrates in Wrangell St. Elias National Park. Sarah Laske (USGS – ASC) collects benthic macroinvertebrates using a kick net in a lake in Wrangell St. Elias National Park, Alaska, as part of a study examining mercury in lake food webs.
Collecting benthic macroinvertebrates in Wrangell St. Elias National Park. Sarah Laske (USGS – ASC) collects benthic macroinvertebrates using a kick net in a lake in Wrangell St. Elias National Park, Alaska, as part of a study examining mercury in lake food webs.
Collecting zooplankton in Wrangell St. Elias National Park
Sarah Laske (USGS - ASC) collects zooplankton from a lake using a plankton net in Wrangell St. Elias National Park as part of a study examining mercury in lake food webs. Sam Graf (NPS - LACL) angles.
Sarah Laske (USGS - ASC) collects zooplankton from a lake using a plankton net in Wrangell St. Elias National Park as part of a study examining mercury in lake food webs. Sam Graf (NPS - LACL) angles.
Lake trout otolith section
Cross section of a lake trout (Salvelinus namaycush) otolith collected from a fish in Lake Clark National Park. Otoliths, also known as 'earstones' are hard, calcium carbonate structures located directly behind the brain of bony fishes.
Cross section of a lake trout (Salvelinus namaycush) otolith collected from a fish in Lake Clark National Park. Otoliths, also known as 'earstones' are hard, calcium carbonate structures located directly behind the brain of bony fishes.
Filtering phytoplankton from lake water
Phytoplankton is filtered from lake water for analysis of mercury content. Photo courtesy of U.S. National Park Service, Public Domain.
Phytoplankton is filtered from lake water for analysis of mercury content. Photo courtesy of U.S. National Park Service, Public Domain.
Water collection, Alaska
Biologist collects water from a lake in Lake Clark National Park. Photo courtesy of U.S. National Park Service, Public Domain.
Biologist collects water from a lake in Lake Clark National Park. Photo courtesy of U.S. National Park Service, Public Domain.
Juvenile sockeye salmon, Alaska
Juvenile sockeye salmon (Oncorhynchus nerka) captured in Lake Clark National Park as part of a study examining mercury in lake food webs.
Juvenile sockeye salmon (Oncorhynchus nerka) captured in Lake Clark National Park as part of a study examining mercury in lake food webs.
Scientist holding lake trout
Lake trout (Salvelinus namaycush). Lake trout captured in Lake Clark National Park as part of a study to examine mercury biomagnification in lake food webs. Photo courtesy of U.S. National Park Service, Public Domain
Lake trout (Salvelinus namaycush). Lake trout captured in Lake Clark National Park as part of a study to examine mercury biomagnification in lake food webs. Photo courtesy of U.S. National Park Service, Public Domain
Mercury concentrations in fish likely reflect different energy sources in lake food webs. Species, populations, or individuals may contain higher and variable concentrations of mercury, which may relate directly to prey mercury content, diets of fish, and fish foraging strategies.
Return to Ecosystems >> Fish and Aquatic Ecology
Sources/Usage: Public Domain. View Media Details
Mercury (Hg) is a toxic contaminant that threatens the health of aquatic ecosystems and species by affecting neurological, cardiovascular, endocrine, renal, and reproductive function. Particularly concerning, Hg accumulates over time in fish tissue, generally increasing with size and age, especially in long-lived piscivorous species like lake trout (Salvelinus namaycush). When contaminant levels reach specific thresholds (e.g., Environmental Protection Agency [EPA] benchmarks for health and toxicity), fish consumption can be harmful to people and wildlife, and safety advisories can be issued for lakes or species. Hg concentrations measured in resident lake fish at several of Alaska’s National Parks were among the highest measured in the western United States, exceeding both ecological (>90 ng/g wet weight) and human health benchmarks (>300 ng/g wet weight). Yet fish Hg concentrations varied widely across and within park lakes and among individuals in the same lake. Because diet is the main Hg accumulation pathway in fish, we aim to investigate the dietary pathways and Hg bioaccumulation from prey to predator.
The movement of Hg through lake food webs is related to within-lake biological processes like Hg methylation rate, biogeochemical characteristics, and energy transfer between trophic levels. By sampling a top predator (lake trout), associated prey species, and primary producers we can trace Hg through lake food webs and determine whether specific energy pathways promote bioaccumulation. In sampling across several National Parks, information will be gathered on limnological, morphological, and biogeochemical characteristics of a diverse set of lakes, providing a baseline of information to study Hg pathways in additional parks, in food webs with different species, or in the future.
Learn more about a sampling effort conducted with the U.S. Geological Survey and National Park Service in Lake Clark, Wrangell-St. Elias, and Gates of the Arctic national parks and preserves and Noatak National Preserve. National Park Article: Tracing Mercury through Lake Food Webs
Sources/Usage: Public Domain. View Media Details
Fish and Aquatic Ecology
Fish and aquatic habitats in Alaska support important commercial, sport, and subsistence fisheries and provide forage fish that support wildlife populations. The USGS Alaska Science Center conducts interdisciplinary research to inform local, state, federal, and international policy makers regarding conservation of fish, aquatic species, and their habitats. We work collaboratively with hydrologists...
Images related to this project below.
Lake in Wrangell St. Elias National Park
Lake in Wrangell St. Elias National Park. This is part of a study examining mercury in lake food webs.
Lake in Wrangell St. Elias National Park. This is part of a study examining mercury in lake food webs.
Round whitefish in Wrangell St. Elias National Park
Round whitefish in Wrangell St. Elias National Park. Round whitefish (Prosopium cylindraceum) were collected as part of a study examining mercury in lake food webs.
Round whitefish in Wrangell St. Elias National Park. Round whitefish (Prosopium cylindraceum) were collected as part of a study examining mercury in lake food webs.
Longnose sucker in Wrangell St. Elias National Park
Longnose sucker in Wrangell St. Elias National Park. Longnose suckers (Catostomus catostomus) were collected as part of a study examining mercury in lake food webs.
Longnose sucker in Wrangell St. Elias National Park. Longnose suckers (Catostomus catostomus) were collected as part of a study examining mercury in lake food webs.
Burbot in Wrangell St. Elias National Park
Burbot in Wrangell St. Elias National Park. Burbot (Lota lota) were collected as part of a study examining mercury in lake food webs.
Burbot in Wrangell St. Elias National Park. Burbot (Lota lota) were collected as part of a study examining mercury in lake food webs.
Fishing for lake trout in Wrangell St. Elias National Park
Fishing for lake trout (Salvelinus namaycush) in Wrangell St. Elias National Park. Sam Graf (NPS – LACL) and Ashley Stanek (USGS – ASC) angle for lake trout (Salvelinus namaycush) in Wrangell St. Elias National Park as part of a study examining mercury in lake food webs.
Fishing for lake trout (Salvelinus namaycush) in Wrangell St. Elias National Park. Sam Graf (NPS – LACL) and Ashley Stanek (USGS – ASC) angle for lake trout (Salvelinus namaycush) in Wrangell St. Elias National Park as part of a study examining mercury in lake food webs.
Fyke net in Wrangell St. Elias National Park
Fyke net in Wrangell St. Elias National Park. Sam Graf (NPS – LACL) adjusts a fyke net installed in a lake in Wrangell St. Elias National Park. Fyke nets are used to non-lethally capture fish.
Fyke net in Wrangell St. Elias National Park. Sam Graf (NPS – LACL) adjusts a fyke net installed in a lake in Wrangell St. Elias National Park. Fyke nets are used to non-lethally capture fish.
Arctic grayling in Wrangell St. Elias National Park
Arctic grayling (Thymallus arcticus) in Wrangell St. Elias National Park. Arctic grayling were collected as part of a study examining mercury in lake food webs.
Arctic grayling (Thymallus arcticus) in Wrangell St. Elias National Park. Arctic grayling were collected as part of a study examining mercury in lake food webs.
Lake trout sampling
Lake trout with stomach contents in Wrangell St. Elias National Park. Dorsal muscle collection and stomach content analysis are used to evaluate biomagnification of mercury in Lake trout (Salvelinus namaycush). Stomach contents visible below the fish consist primarily of slimy sculpin (Cottus cognatus).
Lake trout with stomach contents in Wrangell St. Elias National Park. Dorsal muscle collection and stomach content analysis are used to evaluate biomagnification of mercury in Lake trout (Salvelinus namaycush). Stomach contents visible below the fish consist primarily of slimy sculpin (Cottus cognatus).
Collecting benthic macroinvertebrates in Wrangell St. Elias National Park
Sam Graf (NPS – LACL) collects benthic macroinvertebrates using an Eckman grab in Wrangell St. Elias National Park as part of a study examining mercury in lake food webs.
Sam Graf (NPS – LACL) collects benthic macroinvertebrates using an Eckman grab in Wrangell St. Elias National Park as part of a study examining mercury in lake food webs.
Collecting benthic macroinvertebrates
Collecting benthic macroinvertebrates in Wrangell St. Elias National Park. Sarah Laske (USGS – ASC) collects benthic macroinvertebrates using a kick net in a lake in Wrangell St. Elias National Park, Alaska, as part of a study examining mercury in lake food webs.
Collecting benthic macroinvertebrates in Wrangell St. Elias National Park. Sarah Laske (USGS – ASC) collects benthic macroinvertebrates using a kick net in a lake in Wrangell St. Elias National Park, Alaska, as part of a study examining mercury in lake food webs.
Collecting zooplankton in Wrangell St. Elias National Park
Sarah Laske (USGS - ASC) collects zooplankton from a lake using a plankton net in Wrangell St. Elias National Park as part of a study examining mercury in lake food webs. Sam Graf (NPS - LACL) angles.
Sarah Laske (USGS - ASC) collects zooplankton from a lake using a plankton net in Wrangell St. Elias National Park as part of a study examining mercury in lake food webs. Sam Graf (NPS - LACL) angles.
Lake trout otolith section
Cross section of a lake trout (Salvelinus namaycush) otolith collected from a fish in Lake Clark National Park. Otoliths, also known as 'earstones' are hard, calcium carbonate structures located directly behind the brain of bony fishes.
Cross section of a lake trout (Salvelinus namaycush) otolith collected from a fish in Lake Clark National Park. Otoliths, also known as 'earstones' are hard, calcium carbonate structures located directly behind the brain of bony fishes.
Filtering phytoplankton from lake water
Phytoplankton is filtered from lake water for analysis of mercury content. Photo courtesy of U.S. National Park Service, Public Domain.
Phytoplankton is filtered from lake water for analysis of mercury content. Photo courtesy of U.S. National Park Service, Public Domain.
Water collection, Alaska
Biologist collects water from a lake in Lake Clark National Park. Photo courtesy of U.S. National Park Service, Public Domain.
Biologist collects water from a lake in Lake Clark National Park. Photo courtesy of U.S. National Park Service, Public Domain.
Juvenile sockeye salmon, Alaska
Juvenile sockeye salmon (Oncorhynchus nerka) captured in Lake Clark National Park as part of a study examining mercury in lake food webs.
Juvenile sockeye salmon (Oncorhynchus nerka) captured in Lake Clark National Park as part of a study examining mercury in lake food webs.
Scientist holding lake trout
Lake trout (Salvelinus namaycush). Lake trout captured in Lake Clark National Park as part of a study to examine mercury biomagnification in lake food webs. Photo courtesy of U.S. National Park Service, Public Domain
Lake trout (Salvelinus namaycush). Lake trout captured in Lake Clark National Park as part of a study to examine mercury biomagnification in lake food webs. Photo courtesy of U.S. National Park Service, Public Domain