Navicula gregaria
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Category
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Length Range16-35 µm
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Width Range4.1-7.0 µm
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Striae in 10 µm14-18 in the center valve
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ContributorMarina Potapova - Feb 2011
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ReviewerMark Edlund - Oct 2011
Identification
Description
Valves are lanceolate with protracted apices. The axial area is narrow and straight. The central area is asymmetric and elliptical. The raphe is straight, with external proximal raphe ends sharply bent toward primary side of the valve. Striae are slightly radiate around the center, becoming parallel, then convergent at the apices. The areolae are clearly visible under LM, numbering 25-32 in 10 μm.
Note that the concept presented here is broad. Others (Lange-Bertalot 2001) report that two distinct morphologies are present on the original Donkin microslide. There is additional discussion on N. gregaria and N. supergregaria in Lange-Bertalot (2001, pg. 85-86, figs. 8-25).
Autecology
This taxon is widespread in lakes and rivers of the US, particularly in sites of high pH, alkalinity, and conductance. It occurs in streams with high embeddedness, turbidity and measures of total human disturbance.
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Size Range, µm3
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Motility
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Attachment
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Habitat
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Colony
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Occurrence
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BCG
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Waterbody
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Distribution
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Original Description
Navicula gregaria, n. sp.-Form on S. V. broadly lanceolate, apiculate; striæ obscure.
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BasionymNavicula gregaria
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AuthorDonkin 1861
Original Images
Citations & Links
Citations
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Publication Link: 10.1080/0269249X.1995.9705330
Links
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Index Nominum Algarum
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GenBank
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North American Diatom Ecological DatabaseNADED ID: 46023
Cite This Page
Potapova, M. (2011). Navicula gregaria. In Diatoms of North America. Retrieved December 26, 2024, from https://diatoms.org/species/45791/navicula_gregaria
Responses
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Navicula gregaria 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.
Navicula gregaria
- Valves lanceolate with protracted apices
- Central area asymmetric
- External proximal raphe ends bent toward primary side
- Striae slightly radiate around the center
- Areolae clearly visible under LM
Valves are lanceolate with protracted apices, 4.1-7.0 µm wide. The central area is asymmetric and elliptic. The external proximal raphe ends are sharply bent toward primary side of the valve. Striae are slightly radiate around the center, numbering 14-18 in 10 µm and are convergent at the apices. The areolae are clearly visible under LM,...