Pleurosira laevis (Ehrenberg) Compère

Common Name: A centric diatom

Synonyms and Other Names:

Biddulphia laevis, Cerataulus laevis

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Identification: Individual diatoms of this species exhibit centric to slightly elliptical valves and are cylindrical in side view. On each valve, one ocellus produces mucilage that allows it to connect to other cells, forming zigzag, filamentous chains that grow epiphytically, epilithically, or form large mats. On individual cells, an ocellus-like process intermediate between a thickened ocellus rim and a rimless pseudocellus is apparent. There are very small spines around the edge of the valves and granules on their surface (Aronson et al. 1975, Compere 1984, Ferreira et al. 1999, Kociolek et al. 1983, Pfiester and Terry 1978). The diameter of P. laevis ranges from 40–55 µm across (Compere 1984, Pfiester and Terry 1978, Wujek and Welling 1981).

Size: diameter 40-55 microns

Native Range: Unclear. Pleurosira laevis is known from different regions of the world, including the south and midwestern United States, the west coast of Africa, and the North Sea (Mills et al. 1993).

Map Key
This map only depicts Great Lakes introductions.

Great Lakes Nonindigenous Occurrences: Pleurosira laevis first occurred in Lake Michigan in 1978 at the Wyoming water treatment plant (Mills et al. 1993, Wujek and Welling 1981).

Ecology: Pleurosira laevis is typically a halophilic and rheophilic species but can survive in lake environments. When it first occurred in Lake Michigan, it was found in regions with higher chloride concentrations in comparison to other parts of the lake and occurred at a concentration of 1% of the total phytoplankton population. It is frequently associated with increased nitrate concentrations. It has been recorded from hard freshwater, oligohaline, and mesohaline environments (Compere 1984, Crayton and Sommerfeld 1979, Whitford 1956, Wujek and Welling 1981).

Means of Introduction: Pleurosira laevis was very likely introduced in ballast water to the Great Lakes (Mills et al. 1993).

Status: Probably established.

Great Lakes Impacts:
Summary of species impacts derived from literature review. Click on an icon to find out more...


Current research on the environmental impact of Pleurosira laevis in the Great Lakes is inadequate to support proper assessment.

Pleurosira laevis has been recorded to dominate phytoplankton assemblages in other locations in the United States. However, these occurrences were in stream ecosystems and it is unclear if P. laevis is capable of out-competing native species in Lake Michigan (Crayton and Sommerfeld 1979). Additionally Ferreira et al. (1999) documented P. laevis growing in homogenous communities with low species richness in Portugal. The population recorded in Lake Michigan by Wujek and Welling (1981) composed approximately 1% of the overall algal abundance and was co-dominant with several native taxa. The abundance of P. laevis and association with Cladophora in tributary environments could impact predator-prey relationships by limiting nutrient and light resources for native algal species. However, presently there is no conclusive research on these trophic interactions and it is not apparent if it would be possible in the Lake Michigan ecosystem (Kociolek et al. 1983).

It is not clear if P. laevis alters water quality. However, this species was found close to a water treatment plant in Lake Michigan and has been observed in other locations where chloride or nitrogen concentrations were elevated (Wujek and Welling 1981).

There is little or no evidence to support that Pleurosira laevis has significant socio-economic impacts in the Great Lakes.

There is little or no evidence to support that Pleurosira laevis has significant beneficial effects in the Great Lakes.

Pleurosira laevis might act as an indicator of poor water quality, as it thrives in water with increased nitrate or chloride (Smucker 2011).


Regulations (pertaining to the Great Lakes region)
There are no known regulations for this species.

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

There are no known biological control methods for this species.

There are no known physical control methods for this species.

There are no known chemical control methods for this species.

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

Remarks: Cryptogenic in Lake Michigan; however, not reported from Great Lakes since original record so may not be a range expander.

References (click for full reference list)

Other Resources:
Author: Kipp, R.M., M. McCarthy, and A. Fusaro

Contributing Agencies:

Revision Date: 9/12/2019

Citation for this information:
Kipp, R.M., M. McCarthy, and A. Fusaro, 2024, Pleurosira laevis (Ehrenberg) Compère: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI,, Revision Date: 9/12/2019, Access Date: 4/13/2024

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.