Meridion circulare

(Greville) Agardh 1831      Category: Araphid
BASIONYM: Echinella circularis Greville 1831

Melosira varians

 

Meridion lineare
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LM scalebar = 10 µm = 40 pixels.

Observations

Contributor: Pat Kociolek - January 2011
Length Range: 17-80 µm
Width Range: 3-4 µm
Striae in 10 µm:

Description

Frustules form fan-shaped colonies and are clavate in girdle view. Valves are linear-clavate and asymmetric to the transapical axis. Costae are present and run transversely across the valves. In many specimens illustrated here, the costae are only present towards the headpole, and are not present towards the footpole. A narrow sternum is present running the length of the valve. A single rimoportula is located near the headpole. Though rarely reported, Meridion species do possess a septum, and these were commonly seen in the material.

Williams (1985, p. 160) reports the breadth of M. circulare as 10-21 µm, while Patrick and Reimer (1966) give 4-8 µm.

Distribution: Meridion circulare is found across the US, in habitats flowing water and spring habitats.

Original Description

Basionym: Echinella circularis
Author: Greville 1831
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Kociolek, P. (2011). Meridion circulare. In Diatoms of the United States. Retrieved May 25, 2013, from http://westerndiatoms.colorado.edu/taxa/species/meridion_circulare

Species: Meridion circulare

Contributor: Pat Kociolek

Reviewer: Rex Lowe

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Image Credit: Pat Kociolek

  1. Valves linear-clavate
  2. Costae present
  3. Narrow sternum present
  4. Single rimoportula present

Valves linear-clavate, asymmetric to the transapical axis. Costae are present running transversely across the valves. A narrow sternum extends the length of the valve. A single rimoportula is located near the headpole.

Compare

This species is separated from M. constrictum by its headpole not being constricted.

Meridion constrictum

Ralfs 1843

Citations

Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.

Williams, D.M. (1985). Morphology, taxonomy and inter-relationships of the ribbed araphid diatoms from the genera Diatoma and Meridion (Diatomaceae: Bacillariophyta). Bibliotheca Diatomologica 8: 1-228.

Links & ID's

Index Nominum Algarum (INA)

INA

California Academy of Sciences (CAS)

Meridion circulare CAS

North American Diatom Ecological Database (NADED)

NADED ID: 45001

Autecology Discussion

Habits

Size Range

101-1000 µm3 (ie Amphora veneta)

Motility

non motile

Attachment

vertical (e.g. stalks)

Habitat

benthic

Colony

colonies common

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

Meridion circulare

Distribution

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

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

Meridion circulare

Responses

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