Identification

Description

Valves are elliptic-lanceolate with broadly rounded and slightly protracted ends. Axial area is narrow, linear, about twice the width of the raphe. Central area is broad and transversely rectangular with rounded corners and irregular borders formed by shortened striae of various lengths. Raphe is lateral, becoming filiform near the proximal ends, which are triangular in shape and deflected slightly toward the secondary side. Striae are mostly radiate, becoming parallel and finally somewhat convergent near the valve ends. Areolae are fine, 26-28 in 10 µm. Voigt discontinuities are clearly evident on the secondary side.

Autecology

Navicula aurora has been recorded in the benthos of streams and lakes, primarily in the Pacific Northwest. This taxon prefers cool and somewhat alkaline waters with low conductivity and low to moderate concentrations of nutrients. Common associates of Navicula aurora in the Northwest include Diploneis ovalis, Nitzschia innominata, Planothidium peragalli, Planothidium daui, Cavinula cocconeiformis, Geissleria schoenfeldii, Achnanthes oblongella, Planothidium rostratum, Planothidium lanceolatoides, and Achnanthidium rivulare.

Our  Lake
Credit: Loren Bahls
Our Lake, Teton County, Montana: home of Navicula aurora
Navicula Aurora Chem 001
Credit: Montana Diatom Database
Abundance-weighted mean values for selected water quality variables measured concurrently with the collection of samples containing Navicula aurora.

Original Description

Valvae elliptico vel lineari-lanceolatae apicibus obtusis late rotundatis, subprotractis, 59-118 µ longae, 15-26 µ latae; raphe directa fissuris terminalibus longis in eandem partem flexis, area axialis distincta, linearis, modice lata, area centralis lata, transapicaliter elliptica; striae transapicales 6.3 ad 7.5 in 10 µ, radiantes, prope apices ad lineam mediam perpendiculares, distincte lineolatae.

  • Author
    Sovereign 1958
  • Length Range
    59-118 µm
  • Width
    15-26 µm
  • Striae in 10µm
    6.3-7.5

Original Images

N Aurora Original Images
N Aurora Original Description

EMAP Assessment

EMAP Distribution

Navicula Aurora 40
Map 40

Response Plots

Navicula Aurora

Cite This Page

Bahls, L. (2011). Navicula aurora. In Diatoms of North America. Retrieved July 23, 2018, from https://diatoms.org/species/navicula_aurora

Responses

The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Navicula aurora 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.