Diatoms of North AmericaDiatoms of North America

Aulacoseira subarctica

(O.Müll.) E.Y.Haw. 1990

Aulacoseira Subarctica Guide
  • Category
    Centric
  • Diameter
    3-14 µm
  • Width Range
    2.5-14 µm
  • Striae in 10 µm
    15-22
  • Synonyms
    Aulacoseira italica subsp. subarctica (O.Müll.) Simonsen

Identification

Aulacoseira subarctica LM2 Aulacoseira subarctica LM3 Aulacoseira subarctica LM1 Aulacoseira subarctica LM4 Aulacoseira subarctica LM5 Aulacoseira subarctica LM6 Aulacoseira subarctica LM7
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Aulacoseira subarctica SEM4 Aulacoseira subarctica SEM3 Aulacoseira subarctica SEM2 Aulacoseira subarctica SEM1

Description

Cells are cylindrical and form long chains. Most cells are narrow, 3-6 µm in diameter, with the ratio of the mantle height to valve diameter greater than 1. Wider cells have the the ratio of the mantle height to valve diameter between 0.3 and 1. The mantle has straight sides and the valve face is flat. Rows of pervalvar areolae are curved to the right (dextrorse). There are 15-22 rows of areolae in 10 µm. The collum is approximately ¼-1/10 of the mantle height. The valve face is plain with or without a peripheral ring of areolae and sometimes has additional rings of small areolae. The spines are robust, pointed and originate from two or, more rarely, from three pervalvar costae. Unlike most other Aulacoseira species, A. subarctica does not have differentiated linking and separation valves; all valves have the spines of the same type. The ringleiste is solid, shelf-like. A few rimoportulae can be visible near ringleiste and near the valve face.

Autecology

This taxon is widespread in freshwaters (Foged 1981). Verified reports from North America are from Alaska (Foged 1981), northeastern US (Camburn and Charles 2000), Nunavut, Saskatchewan, and the Rocky Mountains (Bahls 2021). It is reported to occur within the plankton of oligotrophic to mesotrophic waters of lower electrolyte content (Cox 1996, Bahls 2021). Foged (1981) reported populations in Alaska to prefer circumneutral to alkaline waters. Cox (1996) stated that this taxon occurs in usually acidic waters. Bahls (2021) asserts that this taxon prefers circumneutral waters. Although primarily reported from lentic systems (Camburn and Charles 2000), Bahls (2021) also reports this species from streams.

In the Great Lakes National Parks (Edlund et al. 2011, 2012, 2013), A. subarctica is common in sediment core material from lakes in Voyageurs (Mukooda and Little Trout lakes), Isle Royale (Richie Lake), and Pictured Rocks (Grand Sable and Beaver lakes).

Several research groups consider it an indicator organism and published regional environmental optima and tolerances including:

Wilson et al. (1994): Salinity optimum - 0.58 g/L with a lower limit of 0.05 g/L and an upper limit of 6.75 g/L for populations from lakes on the interior plateau of British Colombia.

Camburn and Charles (2000): Abundance Weighted Mean (AWM) pH – 6.96, pH Tol – 0.80, AWM ANC – 124 µeq/L, ANC Tol – 116 µeq/L, AWM Total Al – 27 µg/L Total Al Tol – 60 µg/L, AWM DOC – 49 µmol/L DOC Tol – 136 µmol/L, TP – 6.52 µg/L, TP Tol – 5.35 µg/L for populations from low alkalinity lakes in northeastern America.

Reavie and Smol (2001): TP – 0.014 mg/L, pH – 8.14, TN – 0.455 mg/L, Max Depth – 26.2 m, Chla – 1.67 mg/L for populations from lakes in southeastern Ontario.

Original Description

Theca zylindrisch, Pleuraseite rechteckig mit geraden oder wenig gekrümmten Enden und abgerundeten Ecken. Disci kreisformig, geradflächig oder mehr oder weniger gekrümmt, die be¬nachbarten eng verbunden, an den Rändern auseinanderweichend, einen Pseudosulcus bildend. In den schmäleren Fäden zwischen je zwei Discen zuweilen ein freier Raum. Discusfläche mit feinen Poren bedeckt, die Ränder mit starken, submarginal inserierten Zähnen besetzt, die mit den gegenüberstehenden der benachbarten Discusränder alternieren. — Porenreihen auf der Mantelfläche gegen die Pervalvarachse geneigt, in Spirallinien vom Halsteil zur Discusfläche aufsteigend und mit den Linien der benachbarten Zellhälfte ein S bildend, in Abständen von ca. 18 auf 10 μ. Poren punktförmig, kräftig, ca. 18 auf 10 μ in den Spiralreihen, in der Querrichtung leicht wellenförmig verlaufend. Zellwand stark, innere Mantellinie gerade. Sulcus eine den kurzen Hals abschnürende tiefere Ringfurche. Höhe 2,5—18 μ; Durchmesser 3 —15 μ. Verhältnis des Durchmessers zur Höhe 1 : 0,2—6,0. Forma recta. Taf. II, Fig. 9. Fäden bis 20 Zellen beobachtet Höhe 10,5—18; Durch¬messer 3—5 μ, Forma curvata vel spiralis. Fäden mehr oder weniger gekrümmt, kreisförmig oder spiralig gewunden, bis zu 4 übereinander liegenden Spiralen von 58 Zellen. Durchmesser der Spiralen 84—127 μ, Kreisschluβ bei mindestens 12 Zellen. Höhe 8,5—12 μ. Durchmesser 4—10,5 μ.

  • Basionym
    Melosira italica subsp. subarctica
  • Author
    O.Müll. 1906
  • Length Range
    3-15 µm
  • Width
    2.5-18 µm
  • Striae in 10µm
    18

Original Images

Orig Ill Ausubarc
Or Desc Ausub

Citations & Links

Citations

Links

Updates

Oct 29, 2024 - Addition of Autecology

From 2010 until 2024 the autecological information on this taxon page was limited. As of this update, information on ecology, biogeography, and environmental optima have been added. - Lane Allen & Mark Edlund

Cite This Page

Potapova, M., English, J., Allen, L., Edlund, M. (2010). Aulacoseira subarctica. In Diatoms of North America. Retrieved November 21, 2024, from https://diatoms.org/species/aulacoseira_subarctica

Responses

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