Credit: Loren Bahls
Little Spearfish Creek, Black Hills, South Dakota: home of Cymbella compacta
Cymbella compacta
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Category
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Length Range45.6-78.3 µm
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Width Range11.4-15.3 µm
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Striae in 10 µm9-11
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SynonymsCymbella helvetica var. compacta (Østrup) Hust. 1955
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Reported AsCymbella helvetica (Krammer and Lange-Bertalot 1986, figs 133: 4, 5)
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ContributorLoren Bahls - Apr 2016
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ReviewerMarina Potapova - Jun 2016
Identification
Description
Valves are dorsiventral with an arched dorsal margin and a slightly convex to nearly flat ventral margin. The apices are rounded and may become weakly protracted in larger specimens. The axial area is narrow and positioned just ventral of the valve mid line. The central area is small and elliptic in shape, or absent. Four to eight elongated areolae present at the proximal ends of median ventral striae. The raphe is lateral, becoming filiform near the proximal and terminal ends. Proximal raphe ends are hooked toward the ventral margin. Terminal raphe fissures are deflected dorsally at a 45 degree angle. Striae are radiate, becoming parallel, and then convergent near the apices. The striae continue around the valve apices. Areolae are distinct in LM and number 22-25 in 10 µm.
Autecology
Krammer (2002) reports Cymbella compacta to be widespread in eutrophic habitats with pH above 7. The specimens shown on this web page are from two streams in the Black Hills of western South Dakota. Geologically and ecologically, the Black Hills are considered an "island range" of the middle Rocky Mountains.
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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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Waterbody
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Distribution
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Original Description
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AuthorØstrup 1910
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Length Range29 µm
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Width12 µm
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Striae in 10µm11
Original Images
Citations & Links
Citations
Links
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Index Nominum Algarum
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North American Diatom Ecological DatabaseNADED ID: 23202
Cite This Page
Bahls, L. (2016). Cymbella compacta. In Diatoms of North America. Retrieved December 16, 2024, from https://diatoms.org/species/49887/cymbella_compacta
Responses
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Cymbella compacta 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.
Cymbella compacta
- Apices not protracted
- Central area small
- Elongated ventral areolae 4-8
- Proximal raphe ends ventrally deflected
Valves have rounded apices that are not protracted. The central area is small or absent. Four to eight elongated areaolae are present on the median ventral striae. Proximal raphe ends are hooked toward the ventral margin.