Epithemia turgida

(Ehrenberg) Kützing 1844      Category: Epithemioid
BASIONYM: Navicula turgida Ehrenberg 1832

Epithemia sorex

 

Eucocconeis alpestris
Show images Hide

LM scalebar = 10 µm = 40 pixels.

Observations

Contributor: Rex Lowe - December 2010
Length Range: 45-166 µm
Width Range: 13.5-17 µm
Striae in 10 µm: 8-10

Description

Valves are dorsiventral and are 45-166 μm long and 13.5 to 17 μm wide. Valves taper toward rounded to rostrate to slightly capitate ends. Striae are 8-10 in 10 μm and costae are 4-5 in 10 μm. There are 2-3 striae between costae. The dorsal margin is strongly convex and the ventral margin is slightly concave. The raphe canal lies against the ventral margin at distal ends of the valve and arches toward the dorsal margin in the valve center. The central arch of the canal is approximately 7-8 μm above the ventral margin reaching almost half the distance to the dorsal margin.

Original Description

Basionym: Navicula turgida
Author: Ehrenberg 1832
Length Range: 45-225 µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Lowe, R. (2010). Epithemia turgida. In Diatoms of the United States. Retrieved May 22, 2013, from http://westerndiatoms.colorado.edu/taxa/species/epithemia_turgida

Species: Epithemia turgida

Contributor: Rex Lowe

Reviewer: Sarah Spaulding

Show guide Hide

Image Credit: Rex Lowe

  1. Striae 8-10 in 10 μm
  2. Costae 4-5 in 10 μm
  3. Raphe canal at ventral margin at distal ends
  4. Central arch of the canal approximately 7-8 μm above the ventral margin

Striae are 8-10 in 10 μm and costae are 4-5 in 10 μm, with 2-3 striae between costae. The ventral margin is slightly concave. The raphe canal lies against the ventral margin at distal ends of the valve and arches toward the dorsal margin in the valve center. The central arch of the canal is approximately 7-8 μm above the ventral margin reaching almost half the distance to the dorsal margin.

Compare

Epithemia turgida has coarser striae (8-10 in 10 μm) than E. adnata (12-14 in 10 μm). In addition, E. turgida has 2-3 striae between adjacent costae and E. adnata has 3-7 striae between adjacent costae. The valves of E. reichelti are more triangular in shape and the raphe canal is positioned on the dorsal margin.

Epithemia adnata

Epithemia reicheltii

Citations

DeYoe, H.R., Lowe, R.L. and Marks, J.C. . (1992). Effects of nitrogen and phosphorus on the endosymbiont load of Rhopalodia gibba and Epithemia turgida (Bacillariophyceae). Journal of Phycology 28: 723–873. 10.1111/j.0022-3646.1992.00773.x

Krammer, K. and Lange-Bertalot, H. (1988). Bacillariophyceae. 2. Teil: Bacillariaceae, Epithemiaceae, Surirellaceae. In: Ettl, H., J. Gerloff, H. Heynig and D. Mollenhauer (eds.) Susswasserflora von Mitteleuropa, Band 2/2. Gustav Fisher Verlag, Jena.

Kützing, F.T. (1844). Die kieselschaligen Bacillarien oder Diatomeen. Nordhausen. 152 pp., 30 pls.

Sims, P.A. (1983). A taxonomic study of the genus Epithemia with special reference to the type species E. turgida (Ehrenb.) Kütz. Bacillaria 6: 211-235.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Epithemia turgida CAS

North American Diatom Ecological Database (NADED)

NADED ID: 32004

Autecology Discussion

Similar to other species of Epithemia, E. turgida contain nitrogen-fixing endosymbiotic cyanobacteria which enable this taxon to become abundant in microhabitats with a low N/P ratio. It is frequently very abundant as an epiphyte on Cladophora and other coarse filamentous algae in western rivers.

Images

Epithemia turgida (larger cells) and E. sorex (smaller cells) epiphytic on Cladophora from the Eel River, California.

Credit/Source: R. Lowe

Live Epithemia turgida showing endosymbiotic cyanobacteria.

Credit/Source: R. Lowe

Habits

Size Range

1001-10,000 µm3 (ie Diatoma vulgaris)
10,001-100,000 µm3 (ie Cymbella tumida)

Motility

moderately motile (e.g. Navicula tripunctata)

Attachment

prostrate (e.g. mucilage pad)

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

Epithemia turgida

Distribution

The distribution map represents the relative abundance of this Epithemia turgida 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 Epithemia turgida was not recorded, or with a red circle indicating the relative abundance of Epithemia turgida.

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

Epithemia turgida

Responses

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