Researchers say oxygen levels have dropped in hundreds of lakes across the United States and Europe over the last 40 years. A new study suggests the oxygen loss can lead to more fish dying and increased algae growth. Scientists examined the temperature and the amount of dissolved oxygen in nearly 400 lakes. Dissolved oxygen is the amount of oxygen gas contained in water. They discovered widespread drops in oxygen levels. The study recently appeared in the publication Nature. It found that dissolved oxygen decreased an average of 5.5 percent in the surface water of the lakes and 18.6 percent in the deep water. The researchers say their findings suggest that warming temperatures and decreased water clarity from human activity are causing oxygen levels to fall. Craig E. Williamson is a biology professor at Miami University in the state of Ohio and a co-writer of the study. He told The Associated Press that testing for oxygen is one of the best ways to judge how healthy water systems are. The study’s findings suggest “a pronounced human footprint,” he said. That footprint includes warming caused by climate change, the researchers said. In addition, decreased water clarity can be caused by runoff from human waste systems, fertilizers, cars and power plants. Losses in dissolved oxygen in Earth’s water systems have been reported before. A 2017 study of oxygen levels in the world’s oceans showed a two percent drop since 1960. But less was known about lakes, which lost two to nine times as much oxygen as oceans, the study found. In the past, other researchers had reported oxygen decreases in individual lakes over a long period of time. But those studies did not examine as many lakes around the world, said Samuel B. Fey. He is a biology professor at Oregon’s Reed College who studies lakes. He was not involved in the latest study. Fey said an important finding was that the researchers were able to show such a notable drop in dissolved oxygen levels. Also, the drops were found at both the surface and in deep parts of the lakes. The deep water drop in oxygen levels may affect organisms that are more sensitive to temperature increases, such as cold water fish. During the summer months, they depend on cooler temperatures found in deeper water. But if deep waters are low in oxygen, the organisms struggle to survive. “Those are the conditions that sometimes lead to fish kills in water bodies,” study co-writer Kevin C. Rose said. This means that a lot of areas cold water fish depend on “could become inhospitable,” he added. Other organisms, Rose said, do better in warmer temperatures at the surface level and can get enough oxygen by remaining there. About one fourth of the lakes studied showed increasing oxygen in surface waters. Rose said this is a bad sign because it points to increased algal blooms the sudden growth of algae. In those lakes, dissolved oxygen was “very low” in deep waters, likely creating unlivable conditions for many species, the researchers said.
Title: Study: Hundreds of Lakes in US, Europe Lose Oxygen
Content: <div id='article-page'><div id='article-content' data-media-url='//news-app-staging.s3.amazonaws.com' data-base-url='//news-app-staging.herokuapp.com' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/A.wav' data-capture-url='//staging.analytics.lingraphica.com/events/capture_news' data-article-title='Study: Hundreds of Lakes in US, Europe Lose Oxygen' data-article-id='5688'><script src='//news-app-staging.herokuapp.com/javascripts/getscripts.js'></script><link rel='stylesheet' href='//news-app-staging.herokuapp.com/stylesheets/article.css' type='text/css' /><div class='article'><p><span data-start-time='0' data-end-time='13563'>Researchers say oxygen levels have dropped in hundreds of lakes across the United States and Europe over the last 40 years.</span> <span data-start-time='13563' data-end-time='24521'>A new study suggests the oxygen loss can lead to more fish dying and increased algae growth.</span> <span data-start-time='24521' data-end-time='35042'>Scientists examined the temperature and the amount of dissolved oxygen in nearly 400 lakes.</span> <span data-start-time='35042' data-end-time='42375'>Dissolved oxygen is the amount of oxygen gas contained in water. </span> <span data-start-time='42375' data-end-time='48271'>They discovered widespread drops in oxygen levels.</span> <span data-start-time='48271' data-end-time='53688'>The study recently appeared in the publication Nature. </span> <span data-start-time='53688' data-end-time='69979'>It found that dissolved oxygen decreased an average of 5.5 percent in the surface water of the lakes and 18.6 percent in the deep water.</span> <span data-start-time='69979' data-end-time='84896'>The researchers say their findings suggest that warming temperatures and decreased water clarity from human activity are causing oxygen levels to fall.</span> <span data-start-time='84896' data-end-time='97333'>Craig E. Williamson is a biology professor at Miami University in the state of Ohio and a co-writer of the study. </span> <span data-start-time='97333' data-end-time='109646'>He told The Associated Press that testing for oxygen is one of the best ways to judge how healthy water systems are. </span> <span data-start-time='109646' data-end-time='117667'>The study’s findings suggest “a pronounced human footprint,” he said.</span> <span data-start-time='117667' data-end-time='126271'>That footprint includes warming caused by climate change, the researchers said. </span> <span data-start-time='126271' data-end-time='139958'>In addition, decreased water clarity can be caused by runoff from human waste systems, fertilizers, cars and power plants.</span> <span data-start-time='139958' data-end-time='148083'>Losses in dissolved oxygen in Earth’s water systems have been reported before. </span> <span data-start-time='148083' data-end-time='159396'>A 2017 study of oxygen levels in the world’s oceans showed a two percent drop since 1960. </span> <span data-start-time='159396' data-end-time='171375'>But less was known about lakes, which lost two to nine times as much oxygen as oceans, the study found.</span> <span data-start-time='171375' data-end-time='182229'>In the past, other researchers had reported oxygen decreases in individual lakes over a long period of time. </span> <span data-start-time='182229' data-end-time='191042'>But those studies did not examine as many lakes around the world, said Samuel B. Fey. </span> <span data-start-time='191042' data-end-time='198292'>He is a biology professor at Oregon’s Reed College who studies lakes. </span> <span data-start-time='198292' data-end-time='202583'>He was not involved in the latest study.</span> <span data-start-time='202583' data-end-time='214000'>Fey said an important finding was that the researchers were able to show such a notable drop in dissolved oxygen levels. </span> <span data-start-time='214000' data-end-time='222021'>Also, the drops were found at both the surface and in deep parts of the lakes.</span> <span data-start-time='222021' data-end-time='235021'>The deep water drop in oxygen levels may affect organisms that are more sensitive to temperature increases, such as cold water fish. </span> <span data-start-time='235021' data-end-time='242833'>During the summer months, they depend on cooler temperatures found in deeper water.</span> <span data-start-time='242833' data-end-time='250854'>But if deep waters are low in oxygen, the organisms struggle to survive.</span> <span data-start-time='250854' data-end-time='262042'>“Those are the conditions that sometimes lead to fish kills in water bodies,” study co-writer Kevin C. Rose said. </span> <span data-start-time='262042' data-end-time='271875'>This means that a lot of areas cold water fish depend on “could become inhospitable,” he added.</span> <span data-start-time='271875' data-end-time='284438'>Other organisms, Rose said, do better in warmer temperatures at the surface level and can get enough oxygen by remaining there.</span> <span data-start-time='284438' data-end-time='292563'>About one fourth of the lakes studied showed increasing oxygen in surface waters.</span> <span data-start-time='292563' data-end-time='303542'> Rose said this is a bad sign because it points to increased algal blooms the sudden growth of algae. </span> <span data-start-time='303542' data-end-time='318792'>In those lakes, dissolved oxygen was “very low” in deep waters, likely creating unlivable conditions for many species, the researchers said.</span> </p></div><div class='control-buttons-sticky' style='display:none;'><div class='control-buttons'><button title='Back' class='back' disabled='disabled'></button><button title='Play' class='play' disabled='disabled'></button><button title='Pause' class='pause' style='display:none;'></button><button title='Forward' class='forward' disabled='disabled'></button><button class='finished-reading' style='display:none;'>Done</button></div></div></div><div id='article-media'><div id='media-image'><img src='https://news-app-production.s3.amazonaws.com/articles/5150/A.jpeg'/></div></div><div id='question-content' style='display:none;'><div class='vocabulary_question question-container' data-question-id=17566 data-hint-location='13563' style='display:none;'><div class='question' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/what_is_algae.wav'>What is algae?</div><div class='choices' data-correct-choice='a simple, nonflowering, and typically aquatic plant'><div class='choice' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/a_simple_nonflowering_and_typically_aquatic_plant.wav'><span>a simple, nonflowering, and typically aquatic plant</span></div><div class='choice' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/a_story_poem_or_picture_that_can_be_interpreted_to_reveal_a_hidden_meaning_typically_a_moral_or_political_one.wav'><span>a story, poem, or picture that can be interpreted to reveal a hidden meaning, typically a moral or political one</span></div><div class='choice' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/a_portable_platform_on_which_goods_can_be_moved_stacked_and_stored_especially_with_the_aid_of_a_forklift.wav'><span>a portable platform on which goods can be moved, stacked, and stored, especially with the aid of a forklift</span></div><div class='choice' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/a_layer_of_dirt_or_froth_on_the_surface_of_a_liquid.wav'><span>a layer of dirt or froth on the surface of a liquid</span></div></div></div><div class='multiple_choice_question question-container' data-question-id=17567 data-hint-location='53688' style='display:none;'><div class='question' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/what_do_researchers_say_are_causing_the_levels_to_fall.wav'>What do researchers say are causing the levels to fall?</div><div class='choices' data-correct-choice='Warming temperatures and decreased water clarity from human activity'><div class='choice' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/warming_temperatures_and_decreased_water_clarity_from_human_activity.wav'><span>Warming temperatures and decreased water clarity from human activity</span></div><div class='choice' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/an_increase_in_predator_fish.wav'><span>An increase in predator fish</span></div><div class='choice' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/polar_bear_migration.wav'><span>Polar bear migration</span></div><div class='choice' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/firehouses_using_too_much_water_from_lakes.wav'><span>Firehouses using too much water from lakes</span></div></div></div><div class='sentence_completion_question question-container' data-question-id=17568 data-hint-location='235021' style='display:none;'><div class='question' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/during_the_summer_months_they_depend_on_cooler_temperatures_found_in__blank__water.wav'>During the summer months, they depend on cooler temperatures found in <span class='blank'>deeper</span> water.</div><div class='choices' data-correct-choice='deeper'><div class='choice' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/deeper.wav'><span>deeper</span></div><div class='choice' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/bluer.wav'><span>bluer</span></div><div class='choice' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/acidic.wav'><span>acidic</span></div><div class='choice' data-sound-name='https://news-app-production.s3.amazonaws.com/articles/5150/drinking.wav'><span>drinking</span></div></div></div><div class='question-buttons'><button class='skip-button'></button><button class='hint-button'></button><button class='speak-button'></button></div></div></div>
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