Adam and Brooke collaborated on a project examining patterns of epilithic metabolism and nutrient uptake across a temperature gradient. They incubated tiles in six streams varying in temperature from about 7 ˚C to 22 ˚C. After about month, Adam and Brooke used chambers to measure metabolism and nutrient uptake. Toom-Toom and Weigs (as they are fondly known in Hengill) used YSI probes to measure changes in dissolved oxygen (DO) during a “light” incubation (first picture) and then during a “dark” incubation (second picture). In the third picture Brooke is showing off our improvised battery pack.
Changes in DO during the “light” incubation reflect the balance of primary production and respiration. Dissolved oxygen changes during the “dark” incubation provide a measure of respiration (we assume primary production doesn’t occur in the dark). After the light and dark incubations, Adam and Brooke added stream water spiked with a small amount of nitrogen and phosphorus. They took several water samples over the next few hours to measure the uptake of nutrients by the epilithon. The forth picture shows Adam taking nutrient samples and the last picture shows epilithon from a cold stream greedily sucking up nutrients.
Toom-Toom and Weigs recently completed their projects. They hope to present their results at next summer’s North American Benthological Society meetings.