Nitzschia sigma
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Category
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Length Range30.0-200.0 µm
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Width Range4.0-13.0 µm
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Striae in 10 µm19-24
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ContributorPat Kociolek - Sep 2011
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ReviewerKalina Manoylov - Jul 2012
Identification
Description
In girdle view, the frustule is distinctly sigmoid. In valve view, depending on the position of the specimen, valves may be distinctly sigmoid. Or, valves may also be linear-lanceolate in the middle of the valve, with the ends curved in opposite directions. The apices are small and capitate. The keel of the raphe is strongly eccentric. Fibula density is 7-12 in 10 µm. Valves lack an expanded central gap in the fibulae.
Autecology
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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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BCG
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Waterbody
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Distribution
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Original Description
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BasionymSynedra sigma
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AuthorKütz. 1844
Original Images
Citations & Links
Citations
Links
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Index Nominum Algarum
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GenBank
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North American Diatom Ecological DatabaseNADED ID: 48087
Cite This Page
Kociolek, P. (2011). Nitzschia sigma. In Diatoms of North America. Retrieved December 16, 2024, from https://diatoms.org/species/46840/nitzschia_sigma1
Responses
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Nitzschia sigma 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.
Nitzschia sigma
- Valve apices curved in opposite directions
- Apices small, capitate
- Striae distinctly punctate
In valve view, the valve apices curve in opposite directions. Valves lack an expanded central gap in the fibulae (called a central nodule by some). The valve apices are small, rounded, and capitate. The striae are distinctly punctate. In girdle view, the frustule has a distinct sigmoid shape.