Although warming and low dissolved oxygen (DO) levels are co-occurring significant climatic stressors in the ocean, the combined effects of these stressors on marine benthic animals have not been well established. Here, we tested the effects of elevated temperatures and low dissolved oxygen levels on the survival, emerging behavior from sediment, and the respiration of juvenile cosmopolitan Manila clams () by exposing them to two temperatures (20 and 23.5°C) and DO levels (3.5 and 6-7 mg/L). Although within previously described tolerable ranges of temperature and DO, this 3.5°C increase in temperature combined with a 50% decrease in DO had a devastating effect on the survival of clams (85% mortality after 8 days). The mortality of clams under normoxia at 23.5°C appeared to be higher than under the low DO condition at 20°C. On the other hand, more clams emerged from sediment under the low DO condition at 20°C than under any other conditions. Oxygen consumption rates were not significantly affected by different conditions. Our results suggest temperature elevation combined with low oxygen additively increases stress on Manila clams and that warming is at least as stressful as low DO in terms of mortality. However, low DO poses another threat as it may induce emergence from sediment, and, thus increase predation risk. This is the first evidence that a combination of warming and deoxygenation stressors should reduce population survival of clams much more so than changes in a single stressor.
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http://dx.doi.org/10.1002/ece3.4041 | DOI Listing |
Mov Ecol
January 2025
Great Lakes Laboratory for Fisheries and Aquatic Science, Fisheries and Oceans Canada, 867 Lakeshore Road, Burlington, ON, Canada.
Background: Globally, temperate lakes are experiencing increases in surface water temperatures, extended periods of summer stratification, and decreases of both surface and deep water dissolved oxygen (DO). The distribution of fish is influenced by a variety of factors, but water temperature and dissolved oxygen are known to be particularly constraining such that with climate change, fish will likely feel the "squeeze" from above and below.
Methods: This study used acoustic telemetry to explore the effects of both thermal stratification and the deoxygenation of the hypolimnion on walleye (Sander vitreus) movements in a coastal embayment in Lake Ontario.
Sci Adv
December 2024
Department of Geosciences, Princeton University, Princeton, NJ, USA.
Many estuaries experience eutrophication, deoxygenation and warming, with potential impacts on greenhouse gas emissions. However, the response of NO production to these changes is poorly constrained. Here we applied nitrogen isotope tracer incubations to measure NO production under experimentally manipulated changes in oxygen and temperature in the Chesapeake Bay-the largest estuary in the United States.
View Article and Find Full Text PDFEcol Lett
November 2024
MARBEC, Univ. Montpellier, Ifremer, CNRS, IRD, Sète/Montpellier, France.
Understanding the response of marine organisms to temperature is crucial for predicting climate change impacts. Fundamental physiological thermal performance curves (TPCs), determined under controlled conditions, are commonly used to project future species spatial distributions or physiological performances. Yet, real-world performances may deviate due to extrinsic factors covarying with temperature (food, oxygen, etc.
View Article and Find Full Text PDFNat Commun
October 2024
GEOMAR Helmholtz Centre for Ocean Research Kiel, 24148, Kiel, Germany.
Ocean deoxygenation is becoming a major stressor for marine ecosystems due to anthropogenic climate change. Two major pathways through which climate change affects ocean oxygen are changes in wind fields and changes in air-sea heat and freshwater fluxes. Here, we use a global ocean biogeochemistry model run under historical atmospheric forcing to show that wind stress is the dominant driver of year-to-year oxygen variability in most ocean regions.
View Article and Find Full Text PDFPLoS One
October 2024
Scripps Institution of Oceanography, University of California San Diego, San Diego, CA, United States of America.
Coral reefs are facing threats from a variety of global change stressors, including ocean warming, acidification, and deoxygenation. It has been hypothesized that growing corals near primary producers such as macroalgae or seagrass may help to ameliorate acidification and deoxygenation stress, however few studies have explored this effect in situ. Here, we investigated differences in coral growth rates across a natural gradient in seawater temperature, pH, and dissolved oxygen (DO) variability in a nearshore seagrass bed on Dongsha Atoll, Taiwan, South China Sea.
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