The diameter of C. atomus can range from 2.5–11.2 µm (Alfinito et al. 2001, Belcher and Swale 1978, Hakansson and Clarke 1997, Stoermer and Yang 1969, Trigueros et al. 2000). In Lake Michigan, the diameter of recorded specimens ranges from 2.5–5 µm (Stoermer and Yang 1969).

Cyclotella atomus grows well at 15-20°C and occurs at maximum abundance at the upper end of this range, although it can also tolerate higher temperatures. It has been recorded in the Great Lakes drainage in spring and summer (Klarer and Millie 1994, Poulickova 1993, Stoermer and Ladewski 1976).

Cyclotella atomus can tolerate turbulence as well as frequent osmotic stress. It has been recorded from fresh, brackish, and saltwater. In Lake Michigan, it occurs in littoral areas that have abnormally high chloride levels. It has made up 8.3% of the diatoms in the Lake Ontario and Oswego River regions during periods of high chloride concentration (Hakansson and Clarke 1997, Makarewicz 1987, Mills et al. 1993, Stoermer and Yang 1969, Tanimura et al. 2004).

Cyclotella atomus can occur as a resting stage in sediments of the Great Lakes (Mills et al. 1993).

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

Environmental	Socioeconomic	Beneficial

There is little or no evidence to support that Cyclotella atomus has significant environmental impacts on the Great Lakes.

Potential:
Cyclotella atomus often forms algal blooms, and in some locations outside of the Great Lakes basin, it composes 95% of the phytoplankton community (Jackson et al. 1987, Kiss 1996, Murakami et al. 1998). In portions of Lake Ontario and Lake Erie, C. atomus has been recorded as an abundant portion of the phytoplankton community, but there are no records of direct effects from competition with native species (Klarer and Millie 1994, Makarewicz 1987).

Cyclotella atomus thrives in a wide range of salinities, at high nutrient levels, and under small-scale turbulence (e.g., 0.38 m s−1) (Jackson et al. 1987, Weckstrom and Juggins 2006, Yang et al. 2005). In eutrophic water bodies where silica is limiting, native diatoms could be in competition with C. atomus, which has a high affinity for silica (Weckstrom and Juggins 2006). Cyclotella atomus has also been seen in locations with reduced algal diversity but this likely due to agricultural eutrophication rather than to the presence of C. atomus.

There are over 50 species of Cyclotella in the Great Lakes, but currently there is no research indicating that there is any genetic interaction between C. atomus and native species. Likewise, C. atomus is often found in locations that have high levels of nutrient pollution, but it does not directly decrease water quality (Jackson et al. 1987, Stoermer and Labewski 1976, Weckstrom and Juggins 2006, Yang et al. 2005).

There is little or no evidence to support that Cyclotella atomus has significant socio-economic impacts on the Great Lakes.
Potential:
Within the Great Lakes basin, C. atomus occurs primarily in shallow waters with high nutrient levels. Cyclotella atomus does not create eutrophic conditions, but it can contribute to the negative effects of eutrophication by further reducing silica availability for native diatoms (Stoermer and Labewski 1976, Weckstrom and Juggins 2006) .

There is little or no evidence to support that Cyclotella atomus has significant beneficial effects on the Great Lakes.
Potential:
The appearance of C. atomus, along with other small planktonic diatoms, can be used as an early indicator that the water quality is deteriorating (Collins et al. 1997, Weckstrom and Juggins 2006, Yang et al. 2005). Stewart et al. (2008) used C. atomus as an indicator of increasing surface temperature due to climate change in Sanagak Lake, Nunavut, Canada. Cyclotella atomus has also been used in paleoflood studies to identify historical floods in an attempt to enhance predictive models for extreme flood events. This same paleoflood data was used to assess the impact of climate change on flood severity and frequency (Medioli and Brooks 2003).

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
The reduction of pollution and nutrient run-off would decrease the viable habitat for C. atomus.

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