The River Cooter has three recognized subspecies, the Eastern River Cooter (P. c. concinna; Le Conte, 1830), the Florida Cooter (P. c. floridana; Le Conte 1830), and the Suwannee Cooter (P. c. suwanniensis; Carr, 1937).  See remarks.

Adult river cooters rarely encounter natural predators due to their large size, though smaller individuals have been observed to be eaten by alligators, raccoons, and wild dogs. The eggs, hatchlings, and juveniles of the species are preyed upon by fire ants, river otters, racoons, foxes, shrews, crows, and rats (Ernst and Lovich, 2009).

Each year, P. concinna lays about 1-6 clutches in nest sites with sandy or loam soil, with an average of 2.3 clutches (varies with subspecies; Buhlmann, 1986). On average, clutch size is about 14.6 eggs, the total number varying from 4-30 eggs per clutch (Ernst and Lovich, 2009; Iverson, 2001). In West Virginia, hatchlings have been observed to overwinter in their nests when laid later in the summer, and emerge in early spring (Buhlmann, 1986). When winter temperatures get low, River Cooters hibernate at the bottom of water bodies (Ernst and Lovich, 2009).

Several records place this species within the Great Lakes basin, indicating that it has already been introduced, though none of these record the species as reproducing or overwintering.

Potential pathway(s) of introduction: Dispersal, unauthorized intentional release, and escape from recreational culture

While P. concinna is  not as active on land as other emydid turtles (Ernst and Lovich, 2009), this species has populations reported as close to the Great Lakes as southern Indiana.

Pseudemys concinna is one of the most commonly traded turtles available for affordable prices in pet shops and online (Masin et al., 2013). Like other aquatic turtle species, River Cooters may be housed in garden ponds for aesthetic enjoyment or released in small inoculum into wild or urban settings for religious purposes (Everard et al., 2018). Because this species is widely available and is a popular pet, introductions through unauthorized releases and escape from ornamental ponds is likely common.

River cooters are native to the southeastern U.S., with scattered non-native populations recorded as far north as Massachussetts.

No records of Pseudemys concinna reproducing or overwintering in the Great Lakes have been published in the literature.

Pseudemys concinna has a moderate probability of establishment if introduced to the Great Lakes (Confidence level: moderate).

Pseudemys concinna has a somewhat broad physiological tolerance to varying abiotic factors but is not as adaptable as the Red-eared Slider, Trachemys scripta elegans. For instance, the River Cooter is not very tolerant of pollution and prefers to live in clear water (Ward and Jackson, 2008). When winter temperatures get low, River Cooters hibernate at the bottom of water bodies or in mud (Ernst and Lovich, 2009). Ultsch (1985) found that P. concinna could only survive for about 50 days submerged at 3^oC in anoxic conditions - this would not fare well in the Great Lakes as temperatures drop very low in the winter and anoxic conditions become present. In aerated water, however, Ultsch (1985) found that the River Cooter can survive submerged at 3^oC for about 150 days. The mean critical thermal maximum of P. concinna is 41.8^oC and the average temperature for losing the ability to right itself during heat stress is 39.3^oC (Ernst and Lovich, 2009).

Habitat and food resources are likely to be abundant and available for invasive P. concinna. River Cooters can live in a wide variety of freshwater habitats and are generally found in lotic habitats: rivers, large streams, and impoundments.There are also many accounts of P. concinna grazing in or inhabiting brackish environments (Agha et al., 2018). For instance, a large group of River Cooters were observed eating coastal seagrasses past the mouth of the Suwannee River in Florida. They are assumed to have a relatively high tolerance of salinity compared to other freshwater turtles, though no formal measurements have been made regarding their salinity tolerances (Jackson, 1995). Adult River Cooters are generally herbivores while juveniles prefer carnivorous diets (Ernst and Lovich, 2009). Their diets are flexible, however, and a variety of food items (both plant and animal matter) have been found in their stomachs in a number of studies including algae, plants, insects, sponges, gastropods, bryozoans, small fish, and tadpoles (Ernst and Lovich, 2009).

In comparison to the endemic turtles of the Great Lakes, P. concinna has a greater average fecundity. Each year, P. concinna lays up to 6 clutches in nest sites, with an average of 2.3 clutches and 4-30 eggs (average of 14.6 eggs; varies with subspecies; Buhlmann, 1986). However, females mature slowly and can take up to 13-24 years to reach sexual maturity which could potentially preclude its ability to establish a stable population in the Great Lakes (Ernst and Lovich, 2009). In contrast, the endemic spotted turtle (Clemmys guttata) lays up to 1-2 clutches per year, with a range of 1-14 eggs and an average of 3.1 eggs per clutch (Ernst and Lovich, 2009). In addition, the endangered Blanding’s Turtle (Emydoidea blandingii) lays 1-2 clutches a year, with a clutch size of 3-22 eggs. The fecundity of the Blanding’s Turtle varies geographically and a study suggested that only about 48% of all females nest per year (Ernst and Lovich, 2009).

In its native range, P. concinna is adapted to warmer water and air temperatures and can tolerate brackish environments and moderate currents. In future climate change scenarios, it would likely benefit from climate change in the Great Lakes basin as current abiotic conditions may prevent it from successfully overwintering there (Agha et al., 2018; Ernst and Lovich, 2009).

Due to the lack of research, it remains unknown whether or not the River Cooter will outcompete native species in the Great Lakes for resources.

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

Environmental	Socioeconomic

Little research suggests that Pseudemys concinna will act as a vector for virulent diseases in its invaded range or outcompete native species in the Great Lakes. However, reptile pets are often kept in unsanitary conditions and act as reservoirs for Salmonella spp. Pseudemys concinna is a known host of Salmonella enterica and it is likely to transfer the bacterium to native species if already infected (Back et al., 2016). In addition, a necrotizing shell disease was found in P. concinna in Lake Blackshear, Georgia. Additional ailments were found in the turtle such as bacterial and fungal infections, trematode ova, and inflammatory lesions on its viscera (Garner et al., 1997). This was an isolated event likely due to degraded environmental conditions and did not appear to affect other surrounding aquatic communities. River Cooters are also known to host blood flukes and herpesviruses, but no reports of transference to native species have been recorded in the literature (Roberts et al., 2018; Marschang, 2018). Finally, there are no records of P. concinna outcompeting native species for resources due to competitive advantages.

Pseudemys concinna has the potential for high socio-economic impact if introduced to the Great Lakes.

From 1970 to 1971 alone, about 280,000 of all salmonellosis cases in the United States were linked to popular pet turtles, costing millions of dollars in medical expenses (Lamm et al.,1972). Pet ownership of turtles was associated with cases of Salmonella spp. outbreaks in Americans from Connecticut, Utah, Atlanta, Santa Clara, and Seattle (Lamm et al. 1972). Salmonellosis can be fatal, especially for children (Center for Disease Control 2007 in Queensland DAF Risk Assessment). As a result, in 1975, the U. S. banned the sale and public distribution of live turtles and viable turtle eggs measuring less than 4 inches in carapace length to mitigate the spread of salmonellosis in humans (40 Fed. Reg. 22543). Still, from 2006-2014, 15 salmonellosis outbreaks associated with turtles were reported in multiple states (Cohen et al. 1980). Pseudemys concinna is no exception, and it is known to spread Salmonella enterica to humans (Back et al., 2016).

Pseudemys concinna has the potential for high beneficial impact if introduced to the Great Lakes.

The River Cooter could serve as a possible biocontrol agent for introduced or watchlist macrophyte species in the Great Lakes. In previous studies, Pseudemys concinna suwanniensis displayed a preference for a highly invasive macrophyte, Hydrilla verticillata, in Gilchrist Spring Park, Florida (Adler et al., 2018; Johnston et al., 2018). Adler et al. (2018) suggest that this species may be useful as an effective biocontrol agent for invasive macrophytes, since it has displayed a similar preference for other invasive plant species, such as Egeria densa. In addition, many people enjoy River Cooters as pets, and some cultures consider it a delicacy (Masin et al., 2013; Abd Rabou, 2020).

In 1975, the U. S. banned the sale and public distribution of live turtles and viable turtle eggs measuring less than 4 inches in carapace length to mitigate the spread of salmonellosis in humans, particularly in young children (40 Fed. Reg. 22543). This regulation does not apply to the distribution of turtles for educational, scientific, or exhibitional purposes and does not impact business related exports internationally.

In Illinois (Ill. Admin. Code tit. 8, § 25.110(c)), it is illegal to sell or possess turtles and turtle eggs that violate the Public Health Service Act (42 USCA 264; 21 CFR 1240.62; 2005) and Section 3372 of the Lacey Act (16 USCA 3372). The River Cooter is not an approved species on the Aquatic Life Approved Species List for aquaculture, transportation, stocking, importation and/or possession in the State of Illinois (515 ILCS 5/20-90). In Indiana (312 Ind. Admin. Code 9-5- 7.5), it is illegal to sell turtles of any species or origin that are less than 4 inches in carapace length unless it is associated with scientific research, an accredited museum, educational institution, college, university, or government agency. In Minnesota, the River Cooter is subject to regulation (it is not listed as an unregulated nonnative species) and its introduction is prohibited by the State (MN Admin. Rules 6216.0270, MN Statute 84D.06). In Michigan (Mich. Comp. Laws § 287.312), it is legal to sell turtles and viable eggs under 4 inches if the distributor provides a health advisory sheet with the purchase. In New York (N.Y. Comp. Codes R. & Regs. tit. 10 § 2.58(a)), it remains illegal to sell small turtles and health advisory warnings must be posted near every commercial or educational display where turtles may be handled by the public. In addition, turtles in NY may be tested for salmonellosis at any time and ordered humanely euthanized if they test positive for bacterial infections by health officials. Pennsylvania (35 PA. Code § 1071) maintains federal law and reinforces the ban on the sale of small turtles.

Refer to the CDC website for all regulations related to salmonellosis (https://www.cdc.gov/phlp/docs/turtle-menu.pdf).

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

Control

Physical

Because adult Pseudemys concinna prefers to eat plants and algae, it is notoriously difficult to survey and capture using standard baited hoop-net traps (Mali et al., 2018). Snorkel surveys, however, have been found to be more effective in Pseudemys monitoring programs when water clarity is good (Mali et al., 2018; Sterrett et al., 2010). In addition, basking traps are relatively successful during warm summer months since Pseudemys species tend to bask in large numbers (Mali et al., 2018; MacCulloch and Gordon, 1978).

In tank experiments, Kang et al. (2021) found that using a heated basking substrate to bait P. concinna may be an effective method for removing invasive individuals in the wild. P. concinna demonstrated a preference for a heated substrate when choosing between that and a substrate of ambient temperature. This is consistent with studies investigating the role of basking in the physiology of emydid turtles, as higher temperatures in turtles stimulate metabolism, increase digestion, and promote growth (Kang et al., 2021). In their work, Kang et al. (2021) also suggest that using heated lures or microhabitats in future trap designs may increase the capture rate of P. concinna in areas of concern.