Aulacoseira islandica

(O. Müller) Simonsen 1979      Category: Centric
BASIONYM: Melosira islandica Müller 1906
SYNONYM(S): Aulacoseira islandica ssp. helvetica (O. Müller) Simonsen 

Aulacoseira humilis


Aulacoseira italica

LM scalebar = 10 µm = 80 pixels.


Contributor: David R.L. Burge | Mark Edlund - July 2015
Diameter: 5.5-20.4 µm
Mantle Height: 8.9-18.3 µm
Rows of areolae in 10 µm: 12-14


Frustules are cylindrical, most often observed in girdle view as long filamentous colonies attached at the valve face to sister cells by linking spines. The valve face is flat and mantle is straight (8.9-18.3 µm high), becoming slightly curved near the valve face. The ratio of the mantle height to valve diameter greatly varies. Pervalvar rows of uniformly circular areolae form striae that run parallel to the mantle sides, occasionally curving slightly to the right (dextrorse). Interstriae terminate at the base of a spine. Separation spines are short and tapered, about as wide as a single areola. Linking spines are small and spathulate. Pervalvar rows of areolae occur 12-14 in 10 µm.

Valve polymorphism is common in A. islandica (Stoermer et al. (1981). Cell silicification and striae coarseness vary within populations, and attributed to silica availability (Stoermer et al. 1985). Early publications referred to filaments with only thickly silicified valves as alpha forms, filaments with only thinly silicified cells as beta forms, and filaments with valves with both types of silicification as gamma forms (Müller 1906). With more lightly silicified specimens occurring under low silica conditions, many authors regard this lightly silicified variety, often called A. islandica ssp. helvetica to be a morphotype (Stoermer et al. 1985, Genkal et al. 1986, Krammer and Lange-Bertalot 1991, Siver and Kling 1997). The images presented here document the moderately silicified form of A. islandica.

Alternatively, others have proposed that polymorphic variation is associated with seasonal life history strategies (Jewson et al. 2010). In the closely related species, Aulacoseira baicalensis (K. Meyer) Simonsen, longer and more heavily silicified forms were produced seasonally upon stratification. These cells functioned as resting cells capable of perennating in cooler waters of 50-150 m deep until autumn overturn.

Aulacoseira islandica also varies in striae and the spine structure. Two types of striae have been observed: 1) coarse striae comprised of complex areolae, which may be uniseriate or biseriate, and 2) fine striae that are uniseriate (Stoermer et al. 1981, Chou 1996). Furthermore, areolae may vary from round to slit-like (Siver and Kling 1997). In fact, the two types of areolae have been observed within the same filament (Siver and Kling 1997).

Both linking and separation spines differ within A. islandica. Separation spines are sharply tapered or lanceolate, while linking spines are spathulate (Chou 1996). The areolae and spine polymorphisms occur across the spectrum of silicification polymorphism (Stoermer et al. 1981).

Original Description

Basionym: Melosira islandica
Author: Müller 1906
Diameter: 7-27 µm
Rows of areolae in 10 µm:

Original Description

Original Images

Cite This Page:
Burge, D., and Edlund, M. (2015). Aulacoseira islandica. In Diatoms of the United States. Retrieved March 25, 2017, from

Species: Aulacoseira islandica

Contributor: David R.L. Burge | Mark Edlund

Reviewer: Kalina Manoylov


Genkal, S.I. and Popovskaya, G.I. (1991). New data on the diatom morphology of Aulacoseira islandica (Bacillariophyta). Diatom Research 6(2): 255-66. 10.1080/0269249X.1991.9705171

Genkal, S.I., Balanov, I.M. & Korneva, L.G. (1986). Morphology and taxonomy of Melosira islandica O.F. Muller (Bacillariophyta). Biology of Inland Waters. Info. Bull. 72:14-21 .

Houk, V. (2003). Atlas of Freshwater Centric Diatoms with a Brief Key and Descriptions. Part I. Melosiraceae, Orthoseiraceae, Paraliaceae and Aulacoseiraceae. Czech Phycology Supplement, Volume 1, Czech Phycological Society, Olomouc.

Jewson, D.H., Granin, N.G., Zhdarnov, A.A., Gorbunova, L.A. and Gnatovsky, R.Y. (2010). Vertical mixing, size change and resting stage formation of the planktonic diatom Aulacoseira baicalensis. European Journal of Phycology 45: 354-364.

Krammer, K. and Lange-Bertalot, H. (1991). Bacillariophyceae. 3. Teil: Centrales, Fragilariaceae, Eunotiaceae. In Ettl, H., Gerloff, J., Heynig, H. & Mollenhauer, D. (Eds.). Süsswasserflora von Mitteleuropa. 2(3): 1-576. Gustav Fisher Verlag, Stuttgart, Germany.

Lashaway, A.R. and Carrick, H.J. (2010). Effects of light, temperature and habitat quality on meroplanktonic diatom rejuvenation in Lake Erie: implications for seasonal hypoxia. Journal of Plankton Research, 32: 479-490.

Müller, O. (1906). Pleomorphismus Auxosporen und Dauersporen bei Melosira-Arten. Jahrbücher für wissenschaftliche Botanik 43(1):49-88.

Reavie, E.D. and Kireta, A.R. (2015). Centric, Araphid and Eunotioid Diatoms of the Coastal Laurentian Great Lakes. Bibliotheca Diatomologica 62:1-184.

Serieyssol, C.A., Edlund, M.B. and Kallemeyn, L.W. (2009). Impacts of settlement, damming, and hydromanagement in two boreal lakes: a comparative paleolimnological study. Journal of Paleolimnology 42: 497-513. DOI:10.1007/s10933-008-9300-9

Simonsen, R. (1979). The diatom system: ideas on phylogeny. Bacillaria 2: 9-71.

Siver, P.A. and Kling, H. (1997). Morphological observations of Aulacoseira using scanning electron microscopy. Can. J. Bot. 75: 1807–1835.

Stoermer, E.F., Kreis Jr., R.G. and Sicko-Goad, L. (1981). A systematic, quantitative, and ecological comparison of Melosira islandica O. Mull. with M. granulata (Ehrenberg) Ralfs from the Laurentian Great Lakes. J. Great Lakes Res. 7: 345-356.

Stoermer, E.F., Wolin, J.A., Schelske, C.L. and Conley, D.J. (1985). Variations in Melosira islandica valve morphology in Lake Ontario sediments related to eutrophication and silica depletion. Limnology and Oceanography 30: 414-418.

Twiss, M.R., McKay, R.M.L., Bourbonniere, R.A., Bullerjahn, G.S., Carrick, H., Smith, R.E.H., Winter, J.G., D'souza, N.A., Furey, P.C., Lashaway, A.R. and Saxton, M.A. (2012). Diatoms abound in ice-covered Lake Erie: An investigation of offshore winter limnology in Lake Erie over the period 2007 to 2010. Journal of Great Lakes Research 38: 18-30.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA

California Academy of Sciences (CAS)

Aulacoseira islandica CAS

North American Diatom Ecological Database (NADED)

NADED ID: 10032

Autecology Discussion

Aulacoseira islandica is most often found in colonies occurring planktic or tychoplanktic in high latitude or high altitude oligotrophic to mesotrophic large waters (Stoermer et al. 1985, Genkal and Popovskaya 1991, Houk 2003), including large, shallow, and eutrophic post-glacial lakes such as Lake Winnipeg and Lake of the Woods (Siver and Kling 1997, Serieyssol et al. 2009). In the Laurentian Great Lakes A. islandica was observed most abundant in Lake Michigan and Lake Superior (Reavie & Kireta 2015). Recent, massive winter and spring blooms of A. islandica have also been occurring in Lake Erie (Lashaway and Carrick 2010, Twiss et al. 2012).