Accounting for variation in temperature and oxygen availability when quantifying marine ecosystem metabolism

Given human modification of Earth’s ecosystems, it is essential to understand how these changes are influencing ecosystem functioning, including net and gross community production and community respiration. These responses are often estimated by measuring oxygen production in the light (net community production) and consumption in the dark (community respiration). These values can then be combined to estimate gross community production. However, the method used to create “dark” conditions – either experimental darkening during the day or conducting measurements at night – could result in different estimates of respiration and production. These data were used to test this prediction and include measurements of oxygen concentrations under daytime “ambient” light conditions, in darkened tide pools during the day, and during nighttime low tides. We made measurements every 1-3 months over one year in southeastern Alaska. We found that daytime respiration rates were substantially higher than ...