Research ArticleOCEANOGRAPHY

Oxygen supersaturation protects coastal marine fauna from ocean warming

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Science Advances  04 Sep 2019:
Vol. 5, no. 9, eaax1814
DOI: 10.1126/sciadv.aax1814
  • Fig. 1 Dissolved oxygen concentration and water temperature in Red Sea coastal habitats.

    (A) Oxygen production in a mangrove forest floor colonized by a photosynthetic biofilm formed by cyanobacteria, algae, and microphytobenthos that are producing oxygen bubbles during daytime (10:30 a.m., 12 May 2018). Production is enhanced by the warm temperature. In the picture, the colonization of the mangrove tree pneumatophores by this biofilm can also be appreciated. Photo credit: Marco Fusi, King Abdullah University of Science and Technology (KAUST). (B) Example of diel seawater temperature and dissolved oxygen fluctuations, with peaks of oxygen production during the hottest hours that determine local hyperoxic conditions. These data were collected in the mangrove environment during September 2017. (C) Dissolved oxygen concentration and water temperature in the three dominant coastal habitats of the Red Sea between August–September 2016 and August 2017. Oxygen concentration is plotted for 1°C temperature intervals during nighttime or daytime: The box edges enclose the first and third quartiles of the observations, the red line is the median, the whiskers encompass 99.3% of the observations (outliers were omitted for clarity of reading), and the black line shows the oxygen concentration at saturation in seawater (left and center). The cross-correlations between water temperature and lagged dissolved oxygen concentration (right), detrended to analyze the oscillations during the day, show that the two time series are in phase (the Pearson correlation coefficient is highest at zero lag for mangroves and coral reefs and at a 10′ lag for seagrass).

  • Fig. 2 Experimental relationship between water temperature and mortality for six marine species under simulated conditions of habitat normoxia (triangles) and hyperoxia (circles).

    The filled areas represent the 95% confidence intervals (normoxia: red; hyperoxia: cyan) for each three-parameter sigmoid regression (black line). The LT50 of the organisms and R2 for each regression are reported in the figure in red (normoxia, 97 ± 2% of oxygen saturation) or cyan (hyperoxia, 140 ± 3% of oxygen saturation). Temperature ramping was 1°C every 30 min to mimic the daily environmental warming rates. The symbols can hide data points. Animal illustration credit: Allende Bodega Martinez.

  • Fig. 3 Physiological performances of T. crenata under simulated conditions of habitat normoxia (red) and hyperoxia (cyan).

    (A) Metabolic thermal response; the light blue area indicates the extended aerobic performance, red and cyan dots represent individual measurements, and the empty circles are the means ± SE (n = 24). (B) Critical PO2. (C) Lactate recovery. The asterisks in (B) (n = 7, P < 0.05) and (C) (n = 19, P < 0.0001) indicate statistically significant differences between the two groups tested.

  • Fig. 4 Oxygen consumption of T. crenata projected from dissolved oxygen and water temperature measured in a mangrove stand of the Red Sea.

    The dots represent observations made every 5 min between August 2016 and August 2017, and colors indicate the oxygen consumption predicted using the best model (R2 = 0.55) fitted to laboratory measurements, indicated by x. The black line indicates the air-saturation oxygen concentration in water. Black isocurves link locations in the plot with the same density of observations (as indicated in relative units by the isoline labels), i.e., locations around which a similar number of records were observed; see Materials and Methods for more details. The highest metabolic performances occur at high temperature and under oxygenation conditions that largely exceed air saturation. This enhanced thermal performance can be fueled by oxygen supersaturation in the habitat.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/9/eaax1814/DC1

    Fig. S1. High-frequency monitoring dataset of dissolved oxygen and water temperature in the three dominant coastal habitats of the Red Sea between August–September 2016 and August 2017.

    Fig. S2. This picture shows some of the study species that were active during the middle of the day.

    Fig. S3. Diel seawater temperature and dissolved oxygen fluctuations measured with the miniDOT loggers nearby the boundary layer of the seagrass habitat where several animals live, including H. atra and T. crenata among the other species.

    Table S1. Number of valid observations of dissolved oxygen concentration and water temperature during night or day, over temperature intervals of 1°C.

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. High-frequency monitoring dataset of dissolved oxygen and water temperature in the three dominant coastal habitats of the Red Sea between August–September 2016 and August 2017.
    • Fig. S2. This picture shows some of the study species that were active during the middle of the day.
    • Fig. S3. Diel seawater temperature and dissolved oxygen fluctuations measured with the miniDOT loggers nearby the boundary layer of the seagrass habitat where several animals live, including H. atra and T. crenata among the other species.
    • Table S1. Number of valid observations of dissolved oxygen concentration and water temperature during night or day, over temperature intervals of 1°C.

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