Valves are broadly linear with concave, protracted margins. The valves are distinctly to slightly sigmoid, a shape produced by the ends being bent in opposite directions. The apices are narrowly rounded. A keel is located at the valve margin, with very distinct fibulae. Fibulae number 5-8 in 10 µm. Striae are barely visible with DIC or oblique lighting.
Kociolek, P. (2011). Nitzschia brevissima. In Diatoms of North America. Retrieved November 11, 2024, from https://diatoms.org/species/nitzschia_brevissima
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Nitzschia brevissima from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:
ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.