Simple Method of Measuring Seston Respiration in Oligotrophic Lakes

Abstract

A simple technique for measuring the oxygen consumption of seston in oligotrophic waters was developed and tested. Water samples were filtered through 0.45-μm filters. The filters were suspended in biological oxygen demand bottles containing lake water. NaN₃ added to one bottle stopped respiration and served as a control to eliminate abiotic influences during the experiments. The difference in oxygen concentration between the respiring and control samples increased linearly over the 1-d experiments. Filtration of hypolimnetic water samples did not significantly alter the rate of oxygen consumption of the seston. Concentrating the seston increased the change in oxygen concentration so that respiration rates from 2 to 80 mg O₂∙m⁻³∙d⁻¹ could be measured. This method is simple, precise, and can measure very low rates of respiration directly.