Skeletonema potamos
(Weber) Hasle in Hasle & Evensen, (1970)
Common Name:
A centric diatom
Synonyms and Other Names:
Microsiphona potamos
Identification:
This relatively small centric diatom forms chains of 1–10 cells, connected by tubular marginal processes that are cleft at the end and that may vary in length depending on salinity. It exhibits a flattened to slightly rounded valve face and a high mantle. Silicified, granulated, and knobby ribs occur in radial arrangements on the valves and mantle. There are typically 5–8 processes per valve and 5–8 rows of areolae between them (Hasle and Evensen 1976, Kiss et al. 1994). The valve diameter of S. potamos is around 2.6–6.5 µm (Belcher and Swale 1978, Genkal and Kuzmin 1980, Hasle and Evensen 1976, Kiss et al. 1994).
Size:
diameter <7 microns
Native Range:
Unclear. S. potamos is widespread but it is uncertain to which region(s) it should be considered native. See Remarks section for more details.
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This map only depicts Great Lakes introductions.
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Great Lakes Nonindigenous Occurrences:
Skeletonema potamos first occurred in Lake Erie in 1963 at Toledo, Ohio. It has also been recorded from other parts of Lake Erie and its drainage, Lake Ontario, Lake Huron and Lake Superior (Lowe and Kline 1976, Mills et al. 1993, Nicholls et al. 1983, US EPA 2008).
Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Skeletonema potamos are found here.
Table last updated 4/18/2024
† Populations may not be currently present.
Ecology:
Skeletonema potamos is generally considered a warm stenothermic and photophilic species with a broad salinity tolerance, typically found in freshwater rivers, freshwater lakes, tidal estuaries, and coastal waters. It is particularly abundant in eutrophic waters and may co-occur with species of blue-green algae (Bothar and Kiss 1995, Hasle and Evensen 1976, Kiss et al. 1994, Marshall and Alden 1990, Marshall et al. 2006, Mills et al. 1993, Ueno 1992 ). At the Grand River mouth on Lake Erie, the occurrence of S. potamos has been associated with relatively elevated concentrations of phosphorus, nitrogen, and chloride (Nicholls et al. 1983). Skeletonema potamos may reach maxima in abundance in spring, summer, and/or fall (Kiss et al. 1994, Lowe and Kline 1976, Marshall et al. 2006, Nicholls et al. 1983, Sabater and Munoz 1990).
Means of Introduction:
Skeletonema potamos was very likely introduced via the ballast water of ships entering the Great Lakes from North American river drainages outside the basin or from European ports (Mills et al. 1993).
Status:
Established where recorded.
Great Lakes Impacts:
Summary of species impacts derived from literature review. Click on an icon to find out more...
There is little or no evidence to support that Skeletonema potamos has significant environmental impacts in the Great Lakes.
Potential:
Skeletonema potamos has been recorded at densities up to 20,140 cells/ml in the Little Miami River, Cincinnati, OH. In the late summer, during the highest density, S. potamos accounted for approximately 35% of the centric diatoms in the Little Miami River (Weber 1970). Skeletonema potamos is considered a pollution tolerant species and may be more productive than native species in polluted waters (Nicholls et al. 1983). The implications of competition with the native diatom taxa were not specifically investigated.
Skeletonema potamos grows in relatively short (1-10 cells) chains. In polluted water S. potamos grew in chains 2-4 cells long and under those conditions it was considered a functional food chain species (Nicholls et al. 1983). The presence of this species as a food source has not been addressed with regards to the specific impact on predators or other prey species.
There is little or no evidence to support that Skeletonema potamos has significant socio-economic impacts in the Great Lakes.
There is little or no evidence to support that Skeletonema potamos has significant beneficial effects in the Great Lakes.
Realized:
Skeltonema potamos does not directly impact water quality; however, as a pollution tolerant species it can often be used as an indicator of poor water quality (Nicholls et al. 1983).
Management:
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.
Control
Biological
There are no known biological control methods for this species.
Physical
There are no known physical control methods for this species.
Chemical
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:
Skeletonema potamos was first described from the Jensensee in Germany under the name S. subsalsus but then redescribed as S. potamos from the Little Miami River at Cincinnati (Kiss et al. 1994). It is now known from North American rivers on both sides of the continent, and parts of Europe including France, England, Germany, Austria, Hungary, the Ukraine, Russia, and Spain (Belcher and Swale 1978, Kiss et al. 1994, Mills et al. 1993, Sabater and Munoz 1990). Skeletonema potamos also now known from Japanese coastal waters (Ueno 1992) and from the La Trobe River in Australia (Chessman 1985). Some authors have recorded this species as Microsiphona potamos. Hasle and Evensen (1976) showed that it is actually very similar to other species of Skeletonema, and thus suggested the new name. Cryptogenic in Lake Erie; now also present in Lakes Superior, Huron, and Ontario.
References
(click for full reference list)
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, Skeletonema potamos (Weber) Hasle in Hasle & Evensen, (1970): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatlakes/FactSheet.aspx?Species_ID=1689&Potential=N&Type=0&HUCNumber=DHuron, Revision Date: 9/12/2019, Access Date: 4/18/2024
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.