Research ArticleMarine Ecology

Long photoperiods sustain high pH in Arctic kelp forests

See allHide authors and affiliations

Science Advances  14 Dec 2016:
Vol. 2, no. 12, e1501938
DOI: 10.1126/sciadv.1501938
  • Fig. 1 CO2, O2, pH, and light in subarctic and Arctic kelp forests.

    Changes in pCO2, O2, pH, and light during field deployments in kelp forests in subarctic Nuuk at a 15-hour daylight photoperiod (A) (27 August to 5 September 2013) and in the Arctic Disko Bay at a 24-hour daylight photoperiod during midsummer (B) (16 to 25 June 2014). The slopes of linear regressions of the steady decline in pCO2 and increase in pH in the Arctic are indicated.

  • Fig. 2 pH and CO2 levels in aquaria.

    Average pH (A) and CO2 concentration (B) over time in aquaria (n = 3) exposed to different photoperiods (left to right: 12-, 15-, 18-, 21-, and 24-hour light; shading illustrates dark periods) and treatments with different CO2 supply (~200, 400, and 1000 ppm). Latitude/season equivalents of the tested photoperiods are shown at the top of the relevant photoperiod panel; that is, the 15:9 and the 24:0 photoperiods represent the field studies in Nuuk and Disko Bay, respectively.

  • Fig. 3 Macrophyte effects on CO2 in relation to photoperiod.

    (A) CO2 end point as a function of photoperiod (mean ± SE across pCO2 treatments) with an exponential fit (y = 12.82e−0.076x, R2 = 0.96). (B) Mean CO2 removal rate (in micromolar per hour) as a function of photoperiod (mean ± SE across CO2 treatments). (C) Linear regression slopes of mean relative maximum electron transport rate (rETRmax) per unit of CO2 as a function of photoperiod for the three tested species.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/12/e1501938/DC1

    fig. S1. Map of Greenland field locations.

    fig. S2. pH and O2 concentrations in subarctic and Arctic kelp forests.

    fig. S3. Respiration rates of macrophytes in aquaria.

    fig. S4. rETR of macroalgae in Arctic midsummer.

    fig. S5. pH in experimental treatments in the absence of macrophytes.

    table S1. FW biomass of each species in each aquarium.

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. Map of Greenland field locations.
    • fig. S2. pH and O2 concentrations in subarctic and Arctic kelp forests.
    • fig. S3. Respiration rates of macrophytes in aquaria.
    • fig. S4. rETR of macroalgae in Arctic midsummer.
    • fig. S5. pH in experimental treatments in the absence of macrophytes.
    • table S1. FW biomass of each species in each aquarium.

    Download PDF

    Files in this Data Supplement:

Navigate This Article