Valves are elliptic-lanceolate to broadly lanceolate, with obtusely rounded apices. The raphe is weakly lateral. Proximal raphe ends are deflected to the secondary side. Distal raphe fissures are hooked to the secondary side. The axial area is very narrow. The central area is moderately large, rounded and asymmetric. Striae are radiate, becoming convergent at the apices. Areolae are coarse, easily distinguished in LM and number 24 in 10 μm.
Navicula weberi has been collected from 20 lakes and streams in the Northern Rocky Mountains of western Montana, where it is present in low numbers. Here it prefers alkaline waters (pH range = 7.4-9.1) with low to moderate levels of electrolytes (specific conductance range = 49-256 μS/cm).
Valves elliptic-lanceolate to broadly lanceolate with obtusely rounded ends, 29 – 57 μm long, 7.3 –10.3 μm wide. Raphe weakly lateral, proximal endings deflected to the secondary side, distal raphe fissures hooked to the secondary side. Axial area very narrow, central area moderately large, rounded and asymmetric. Striae radiate, becoming convergent at the ends, 9 –10 in 10 μm, lineolae coarse, 24 in 10 μm, easily distinguished in LM. For measurements, n = 23.
Bahls, L. (2012). Navicula weberi. In Diatoms of North America. Retrieved October 13, 2024, from https://diatoms.org/species/navicula_weberi
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Navicula weberi 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.