Navicula aurora

Sovereign 1958      Category: Symmetrical biraphid
BASIONYM: Navicula aurora Sovereign 1958

Navicula antonii

 

Navicula canalis
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LM scalebar = 10 µm = 40 pixels.

Observations

Contributor: Loren Bahls - November 2011
Length Range: 65-130 µm
Width Range: 18-28 µm
Striae in 10 µm: 7-9

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.

Original Description

Basionym: Navicula aurora
Author: Sovereign 1958
Length Range: 59-118 µm
Width Range: 15-26 µm
Striae in 10 µm: 6.3-7.5

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.

Original Images

Cite This Page:
Bahls, L. (2011). Navicula aurora. In Diatoms of the United States. Retrieved May 18, 2013, from http://westerndiatoms.colorado.edu/taxa/species/navicula_aurora

Species: Navicula aurora

Contributor: Loren Bahls

Reviewer: Sarah Spaulding

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Image Credit: Loren Bahls

  1. Large elliptic-lanceolate valves
  2. Central area transversely rectangular
  3. Proximal raphe ends triangular
  4. Terminal striae straight

Navicula aurora has large elliptic-lanceolate valves. Valve ends are broadly rounded and slightly protracted. The central area is transversely rectangular with rounded margins. Proximal raphe ends are triangular and deflected slightly toward the secondary side. Terminal striae are straight, not bent.

Compare

Navicula aurora is distinguished from N. oblonga by its more elliptical (less linear) valves and straight terminal striae; from N. peregrina by its somewhat protracted ends and finer striae and areolae; from N. reinhardtii by its larger and more rounded (less transverse) central area and finer areolae; from N. sovereignii by its rounded rectangular central area and triangular proximal raphe ends; and from N. vulpina by its somewhat protracted ends and more transverse (less circular) central area.

Navicula vulpina

Navicula peregrina

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Navicula sovereignii

Navicula reinhardtii

Navicula oblonga

Citations

Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.

Sovereign, H.E. (1958). The diatoms of Crater Lake, Oregon. Transactions of the American Microscopical Society 77(2):96-134.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Navicula aurora CAS

North American Diatom Ecological Database (NADED)

NADED ID: 46167

Autecology Discussion

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.

Images

Our Lake, Teton County, Montana: home of Navicula aurora

Credit/Source: Loren Bahls

Abundance-weighted mean values for selected water quality variables measured concurrently with the collection of samples containing Navicula aurora.

Credit/Source: Montana Diatom Database

Habits

Size Range

10,001-100,000 µm3 (ie Cymbella tumida)

Motility

moderately motile (e.g. Navicula tripunctata)

Attachment

unattached

Habitat

benthic

Colony

solitary

EMAP Assessment

Sampling for the Environmental Protection Agency (EPA) western Environmental Monitoring and Assessment Program (EMAP) study was completed during the years 2000-2004 (see citations at bottom of this page). Streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming). Over 1200 sites on streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming) were selected for sampling based on a stratified randomized design. This type of design insures that ecological resources are sampled in proportion to their actual geographical presence. Stratified randomized design also allows for estimates of stream length with a known confidence in several “condition classes” (good or least-disturbed, intermediately-disturbed, and poor or most-disturbed) for biotic condition, chemistry and habitat.

EMAP Distribution

Navicula aurora

Distribution

The distribution map represents the relative abundance of this Navicula aurora in the western EMAP study. Relative abundance is a measure of the proportion of cells of this species based on a "fixed count" of 300 total diatom cells counted and identified. Each of the western EMAP sample sites is shown, either with a black dot for sites where Navicula aurora was not recorded, or with a red circle indicating the relative abundance of Navicula aurora.

Note that the size of the proportional symbols varies between species to help show both abundant and rare species.

Scale for the map to the left

EMAP Response Plots

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.

EMAP citations

Results are published in:

Johnson, T., Hermann, K., Spaulding, S., Beyea, B., Theel, C., Sada, R., Bollman, W., Bowman, J., Larsen, A., Vining, K., Ostermiller, J., Petersen, D. Hargett, E. and Zumberge, J. (2009). An ecological assessment of USEPA Region 8 streams and rivers. U.S. Environmental Protection Agency Region 8 Report, 178 p.

Stoddard, J. L., Peck, D. V., Olsen, A. R., Larsen, D. P., Van Sickle, J., Hawkins, C. P., Hughes, R. M., Whittier, T. R., Lomnicky, G. A., Herlihy, A. T., Kaufman, P. R., Peterson, S. A., Ringold, P. L., Paulsen, S. G., and Blair, R. (2005). Environmental Monitoring and Assessment Program (EMAP) western streams and rivers statistical summary. U.S. Environmental Protection Agency Report 620/R-05/006, 1,762 p.

Stoddard, J. L., Peck, D. V., Paulsen, S. G., Van Sickle, J., Hawkins, C. P., Herlihy, A. T., Hughes, R. M., Kaufman, P. R., Larsen, D. P., Lomnicky, G. A., Olsen, A. R., Peterson, S. A., Ringold, P. L., and Whittier, T. R. (2005). An ecological assessment of western streams and rivers. U.S. Environmental Protection Agency Report 620/R-05/005, 49 p.