Projected 21st century compression of mesopelagic habitat in the California current

Abstract Although the mesopelagic zone occupies a substantial volume of the world’s oceans, our results suggest that the livable portion may compress vertically by ~ 40 m or ~ 39% by the end of the century. Using an ensemble of three downscaled climate projections from a high emissions scenario, we...

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Main Authors: Ilysa S. Iglesias, Jerome Fiechter
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-10992-1
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author Ilysa S. Iglesias
Jerome Fiechter
author_facet Ilysa S. Iglesias
Jerome Fiechter
author_sort Ilysa S. Iglesias
collection DOAJ
description Abstract Although the mesopelagic zone occupies a substantial volume of the world’s oceans, our results suggest that the livable portion may compress vertically by ~ 40 m or ~ 39% by the end of the century. Using an ensemble of three downscaled climate projections from a high emissions scenario, we evaluated the connection between anthropogenic greenhouse gas emissions and changes in light and oxygen at depth, which influence the upper and lower limits of mesopelagic habitat in the central California Current. Although the model projects a small deepening (~ 2 m) of the upper light boundary consistent with increased stratification and reduced upper ocean productivity, the main driver of vertical mesopelagic habitat compression is the significant shoaling (by ~ 44 m) of the hypoxic boundary over the course of the 21st century. Differences in dissolved oxygen across ensemble members highlight the potential influence of equatorial dynamics and the California Undercurrent in constraining the future availability of mesopelagic habitat along the U.S. west coast. Mesopelagic ecosystems connect the surface ocean to the deep sea, and a projected decrease in the vertical extent of mesopelagic habitat could have cascading effects on a broader range of marine ecosystem processes and carbon export.
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spelling doaj-art-2a16ffd80aa4446baee3c799e8d39e302025-08-20T03:42:45ZengNature PortfolioScientific Reports2045-23222025-07-0115111210.1038/s41598-025-10992-1Projected 21st century compression of mesopelagic habitat in the California currentIlysa S. Iglesias0Jerome Fiechter1Ocean Sciences Department, University of California, Santa CruzOcean Sciences Department, University of California, Santa CruzAbstract Although the mesopelagic zone occupies a substantial volume of the world’s oceans, our results suggest that the livable portion may compress vertically by ~ 40 m or ~ 39% by the end of the century. Using an ensemble of three downscaled climate projections from a high emissions scenario, we evaluated the connection between anthropogenic greenhouse gas emissions and changes in light and oxygen at depth, which influence the upper and lower limits of mesopelagic habitat in the central California Current. Although the model projects a small deepening (~ 2 m) of the upper light boundary consistent with increased stratification and reduced upper ocean productivity, the main driver of vertical mesopelagic habitat compression is the significant shoaling (by ~ 44 m) of the hypoxic boundary over the course of the 21st century. Differences in dissolved oxygen across ensemble members highlight the potential influence of equatorial dynamics and the California Undercurrent in constraining the future availability of mesopelagic habitat along the U.S. west coast. Mesopelagic ecosystems connect the surface ocean to the deep sea, and a projected decrease in the vertical extent of mesopelagic habitat could have cascading effects on a broader range of marine ecosystem processes and carbon export.https://doi.org/10.1038/s41598-025-10992-1Twilight zoneMesopelagic-epipelagic couplingClimate changeDownscaled climate projectionsRegional ocean modelingDeoxygenation
spellingShingle Ilysa S. Iglesias
Jerome Fiechter
Projected 21st century compression of mesopelagic habitat in the California current
Scientific Reports
Twilight zone
Mesopelagic-epipelagic coupling
Climate change
Downscaled climate projections
Regional ocean modeling
Deoxygenation
title Projected 21st century compression of mesopelagic habitat in the California current
title_full Projected 21st century compression of mesopelagic habitat in the California current
title_fullStr Projected 21st century compression of mesopelagic habitat in the California current
title_full_unstemmed Projected 21st century compression of mesopelagic habitat in the California current
title_short Projected 21st century compression of mesopelagic habitat in the California current
title_sort projected 21st century compression of mesopelagic habitat in the california current
topic Twilight zone
Mesopelagic-epipelagic coupling
Climate change
Downscaled climate projections
Regional ocean modeling
Deoxygenation
url https://doi.org/10.1038/s41598-025-10992-1
work_keys_str_mv AT ilysasiglesias projected21stcenturycompressionofmesopelagichabitatinthecaliforniacurrent
AT jeromefiechter projected21stcenturycompressionofmesopelagichabitatinthecaliforniacurrent