Within each transect, algal mats were visually identified as either orange, red, black, or green. Not all types of algal mats were found within every transect. Algal samples were collected using a cork borer (1.04 cm2) and placed in vials (volume=21.3 mL). Vials of algae were placed in bags to screen sunlight to 0, 0.5, 1.4, 7.7, 16.4, 31.2, 60.7, 67.0, 100 percent of full sunlight for warm temperature incubations and 0, 1.4, 7.7, 31.2, 100 percent of full sunlight for cool temperature incubations. Algae were incubated in the stream for approximately 2.75-4.0 hours typically between 8:50 am and 5:00 pm. Primary productivity was measured as the change in oxygen concentration in the vial using an oxygen microelectrode. Upon completion of incubation, the algae in the vials were taken back to the lab for AFDM processing. Samples were taken in the area of the LTER monumented transect. Samples for ash-free dry mass measurements were filtered through GF/C glass fiber filters and frozen. The samples were dried (100 degrees C) for 24 hours, weighed, ashed (450 degrees C) for 4 hours, rehydrated with water, dried for 24 hours, and reweighed. Net primary productivity (NPP, light bottles) and community respiration (CR, dark bottles) were calculated as follows: NPP or CR (ug C/cm2/hr)=[(((change in mg O2/L x v) x 0.375 C/O2 x 1000 ug/mg)/area/hours incubated], where O2/L = change in oxygen concentration, v = volume of vial (0.0213 L), C/O2 = atom/atom conversion of oxygen to carbon, area = 1.04 cm2.