Fragilaria crotonensis

Kitton 1869      Category: Araphid

Fragilaria amphicephaloides

 

Fragilaria mesolepta
Show images Hide

LM scalebar = 10 µm = 40 pixels.

Observations

Contributor: Eduardo A. Morales | Barry Rosen | Sarah Spaulding - May 2013
Length Range: 60-72 µm
Width Range: 2-3 µm
Striae in 10 µm: 17-18

Description

Valves are lanceolate with capitate ends. The central area is wider than rest of the valve. The valve margins may be undulate, with a central swollen middle of the valve. The valve face is undulate due to raised virgae. The valve face/mantle junction forms a sharp angle. The abvalvar edge of the mantle is shallower toward the valve apices, producing detachment of contiguous cells in girdle view. In girdle view, frustules are lanceolate, wider near the center of the valve. Cells form ribbon-like colonies joined by linking spines. The axial area is lanceolate, with clear fascia at the central area. Striae are distinct, composed of apically elongated areolae (lineolae). Striae are interrupted by spines. Striae are parallel throughout the valve and extend midway onto the valve mantle. Costae are wider than the striae. Spines are dimorphic; spatulate near the valve center and conical near the valve ends. Spines are present along the valve face margin, positioned in line with the striae. Well-developed apical pore fields with round poroids are present on the mantle at both valve ends. One rimoportulae is present on each valve. The rimoportula is located along a stria, close to the axial area. Copulae, or girdle bands, were not observed.

Original Description

Basionym:
Author: Kitton 1869
Length Range: µm
Striae in 10 µm:

Original Description

Fragillaria crotonensis, n.s., F. Kitton.-Frustules linear, inflated at the central part, where they cohere and form ribbon-like filament; valve narrow, acicular; striae faint, moniliform (fig.81).-Croton water, New York, Dr. Edwards.

Original Images

Cite This Page:
Morales, E., Rosen, B., and Spaulding, S. (2013). Fragilaria crotonensis. In Diatoms of the United States. Retrieved April 18, 2018, from http://westerndiatoms.colorado.edu/taxa/species/fragilaria_crotonensis

Species: Fragilaria crotonensis

Contributor: Eduardo A. Morales | Barry Rosen | Sarah Spaulding

Reviewer: Sam Rushforth

Show guide Hide

Image Credit: Barry Rosen, Eduardo Morales, Sarah Spaulding

  1. Valves lanceolate
  2. Colonies ribbon-like
  3. Central valve margin inflated
  4. Spines present

Valves are lanceolate, with an inflated central margin. Valve apices are rounded to capitate. Spines are positioned on the margin, a spine present at the end of a stria. Frustules are joined in ribbon-like colonies.

Compare

Fragilaria tenera has narrowly lanceolate valves with no inflated central margin. Colonies are rarely formed by F. tenera, whereas F. crotonensis commonly forms long ribbon-like colonies with 10-40 (or more) cells.

Fragilaria tenera

Citations

Canter, H.M. and Jaworski, G.H.M. . (1983). A further study on parasitism of the diatom Fragilaria crotonensis Kitton by chytridiaceous fungi in culture. Annals of Botany 52(4): 549-563 .

Crawford, R.M., Canter, H.M. and Jaworski, G.H.M. . (1985). A study of two morphological variants of the diatom Fragilaria crotonensis Kitton using electron microscopy . Annals of Botany 55(4): 473-485.

Saros, J.E., Michel, T.J., Interlandi, S.J. and Wolfe, A.P. (2005). Resource requirements of Asterionella formosa and Fragilaria crotonensis in oligotrophic alpine lakes: implications for recent phytoplankton community reorganizations. Canadian Journal of Fisheries and Aquatic Sciences 62: 1681-1681. doi:10.1139/f05-077

Spaulding, S.A., Otu, M., Wolfe, A.P. and Baron, J. (2015). Paleolimnological records of nitrogen deposition in shallow, high-elevation lakes of Grand Teton National Park, Wyoming, U.S.A. Arctic, Alpine and Antarctic Research 47(4): 701-715.

Wolfe, A.P., Cooke, C.A. and Hobbs, W.O. (2006). Are current rates of atmospheric nitrogen deposition influencing lakes in the eastern Canadian Arctic?. Arctic, Antarctic, and Alpine Research 38: 465-476.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Fragilaria crotonensis CAS

NCBI Genbank Taxonomy

Fragilaria crotonensis NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 34017

Autecology Discussion

Fragilaria crotonensis is a common species in temperate, mesotrophic lakes of North America. Cells can be joined in large ribbon-like colonies. These colonies are resistant to sinking in the water column and help F. crotonensis maintain position in the phytoplankton.

Fragilaria crotonensis, along with Asterionella formosa, is considered a marker that the levels of reactive nitrogen (Nr) have increased above the threshold in oliogotropic lakes of the western United States where diatom assemblages become more like assemblages in mesotrophic and eutrophic lakes (Saros et al. 2005, Wolfe et al. 2006, Spaulding et al. 2015). See the autecology of A. formosa for further discussion.

Images

Living colony of F. crotonensis.

Credit/Source: S. Spaulding

Habits

Size Range

101-1000 µm3 (ie Amphora veneta)

Motility

non motile

Attachment

unattached

Habitat

planktonic

Colony

colonies common

EMAP Assessment

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). Over 1200 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

Fragilaria crotonensis

Distribution

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

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

Fragilaria crotonensis

Responses

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