Aquatic systems are often exposed to stressors from the surrounding environments, and consequently, organisms may incur fitness costs from the development of sublethal abnormalities (Kalvnadi et al. 2018; Mohapatra et al. 2020). Research has demonstrated a link between contaminants in aquatic environments and the development of deformities in animal taxa. For example, exposure to high salinity results in abnormal tail morphology in wood frog larvae (Sanzo and Hecnar 2006). Changes in gill structure, alterations of surface epidermal cells, and skeletal abnormalities, including deformed fins, shortened operculae, and spinal curvature, have also been documented in fish exposed to chemical pollutants, such as heavy metals (Slooff 1982; de Oliveira Ribeiro et al. 2002; Salamat and Zarei 2012). However, this field of study remains relatively underexplored because of inherent challenges associated with quantifying and establishing connections between various sublethal abnormalities and their underlying environmental stressors in field settings, particularly in long-lived vagile vertebrates.

Fitness costs of physical abnormalities in freshwater turtles are often overlooked because of their longevity, apparent ability to tolerate polluted environments, and persistence despite poor physical condition (Congdon et al. 1994; Ferronato et al. 2009; Lovich et al. 2018). Nevertheless, these sublethal effects can provide insights into the extent of environmental stressors (Bell et al. 2006; de Solla et al. 2008; Nagle et al. 2023). Physical abnormalities in turtles are manifested in a variety of ways, including deformities to the skull, limbs, face, and tail; additional or missing scutes; unusual pigmentation; kyphosis (severe spinal curvature); missing appendages; shell lesions; and shell damage (Bell et al. 2006; Davy and Murphy 2009; Lambert et al. 2021; Pignatelli et al. 2023). Dovetail syndrome, a specific form of abnormal scutellation characterized by zig-zagging vertebral scutes, has also been documented in freshwater turtles (Ewert 1979; Moustakas-Verho and Cherepanov 2015).

Shell and body damage are often attributed to direct anthropogenic causes (e.g., a turtle being struck by heavy machinery), and shell lesions may represent signs of bacterial or fungal infection (Woodburn et al. 2019; Lambert et al. 2021; Woodburn et al. 2021; Hastain et al. 2024). Although the exact causative agents of abnormal scutellation are often unclear, microclimate has been shown to influence the development of freshwater turtle embryos. Hatchlings from natural nests have been documented with frequent scute abnormalities and more variation in carapace scute shape, with variability often attributed to environmental fluctuations, including hotter and drier incubation conditions (Telemeco et al. 2013; Zimm et al. 2017; Cordero et al. 2023). Maffucci et al. (2020) noted that scute abnormalities were less frequent in later age classes of loggerhead sea turtles (Caretta caretta). Sim et al. (2014) found some evidence of lower fitness metrics in loggerhead and flatback (Natator depressus) sea turtle hatchlings when comparing hatchlings with modal and nonmodal scutes (e.g., reduced initial swim thrust in N. depressus). Overall, the extent to which abnormal scutellation serves as a selective force remains debated (Velo-Antón et al. 2011; Telemeco et al. 2013; Maffucci et al. 2020; Bentley et al. 2021).

Often, population-level studies encompass a variety of landscape types and associated stressors, which makes it challenging to determine the exact cause of an abnormality. However, some studies have attributed shell deformities to lipophilic contaminant exposure, such as polycyclic aromatic hydrocarbons and polychlorinated biphenyls, in both adult turtles (e.g., Nagle et al. 2018) and hatchlings (e.g., Bell et al. 2006). Nevertheless, the level of contamination does not consistently serve as a predictor of sublethal abnormalities (Davy and Murphy 2009). Even in regions where contaminants are high, identifying a causal link between environmental pollutants and high rates of deformities is difficult (de Solla et al. 2008). It has also been suggested that climatic variation could have interactive effects with environmental pollutants to increase the prevalence of deformities (Davy and Murphy 2009; Telemeco et al. 2013; Maffucci et al. 2020).

The Pecos River is home to 6 freshwater turtle species, 1 of which is conservation-reliant. The river runs approximately 1,500 km across eastern New Mexico and western Texas, USA, and has a drainage area of more than 98,400 km², making it the largest tributary of the Rio Grande River (Jensen et al. 2006). Historically, the Pecos River has been an important source of drinking water for settlers in the region and became the sole resource for irrigating crops and supporting livestock (Hoagstrom 2009; Harley and Maxwell 2018). The lower Pecos River, running from the town of Artesia, New Mexico, to the river’s confluence with the Rio Grande, has been especially impacted by dam construction and channelization, as well as expanding oil and gas extraction practices in the Permian Basin (i.e., water extraction for hydraulic fracturing; Hoagstrom 2009; Pease and Delaune 2021; Mahan et al. 2022; Scanlon et al. 2022). These profound anthropogenic pressures have resulted in declines in water quality through diminished flows and the potential accumulation of contaminants (Hoagstrom 2009; Cheek and Taylor 2015; Mahan et al. 2022). Diminished flows have also been compounded by the megadrought impacting the American Southwest, and climate models predict prolonged conditions of aridity in the future (Seager et al. 2007; Williams et al. 2022; Hernandez and Chen 2023). As a cumulative result of anthropogenic pressures, the lower Pecos River has experienced shifts in native fish species (from freshwater to euryhaline congeners) and the occupancy of freshwater turtles (Cheek and Taylor 2015; Ruhí et al. 2016; Pease and Delaune 2021; Mahan et al. 2022).

Although two-thirds of freshwater turtle species native to New Mexico can be found in the lower Pecos River (Degenhardt et al. 1996), little is known about their populations’ health and status therein. Degenhardt and Christiansen (1974) evaluated the distribution of turtles in New Mexico based on a combination of trapping, hand-captures, and museum records. Nearly 5 decades later, Mahan et al. (2022) evaluated the distribution of the Rio Grande cooter (Pseudemys gorzugi) based on systematic survey efforts. One of the most frequently captured turtle species during these survey efforts was the red-eared slider (Trachemys scripta elegans). Naturalized on all continents except Antarctica, the red-eared slider is one of the most adaptable and widespread freshwater turtle species worldwide (Lever 2003). Although considered invasive in many regions, T. s. elegans is native to the lower Pecos River (Ernst and Lovich 2009). In contrast, the Rio Grande cooter range is restricted to the lower Rio Grande River drainage, and the species is considered Threatened in New Mexico (Bailey et al. 2008; Ernst and Lovich 2009; NMDGF 2016).

Here we use the data from recent freshwater turtle survey efforts in the lower Pecos River in New Mexico (Mahan et al. 2022) to assess the range and frequency of physical abnormalities in P. gorzugi and T. s. elegans, the 2 most commonly encountered hardshell turtles. In addition to identifying the types of physical abnormalities that turtles exhibit as a potential response to environmental stressors, we also documented cases of melanism, a phenomenon known to occur in males of some emydid species (McCoy 1967; Lovich et al. 1990; Hays and McBee 2009; Glorioso et al. 2010; Smith et al. 2016). Melanistic males are typically larger and considered older than their nonmelanistic counterparts, with population-specific female size at maturity being an important predictor of the onset of melanism in males (Lovich et al. 1990; Tucker et al. 1995; Reehl et al. 2006; Hays and McBee 2009; Vaughan and Mali 2024), although environmental conditions may also contribute to pigmentation in hatchlings (Etchberger et al. 1993; Rowe et al. 2006). Combining information on melanism, a proxy for turtle age, and juvenile capture rate provides insights into the age structure of the populations, while visible physical condition of turtles could serve as an indirect indicator of ecological integrity of the lower Pecos River (Yabe 1994; Stone et al. 2015).

METHODS

Freshwater turtle surveys were conducted in the lower Pecos River of New Mexico between May and August of 2020 and 2021. Sixteen sites were surveyed in Eddy County between Brantley and Red Bluff reservoirs (Mahan et al. 2022). These sites were located in a matrix of varying land uses, including 1 site within the city of Carlsbad, New Mexico; a site immediately downstream of the city; and other highly remote locations surrounded by a patchwork of land for agriculture and oil and gas extraction. All sites were visited 3 times within a single season, with 45 baited hoop-net traps deployed for 48 hr during each survey occasion (Mahan et al. 2022). All traps were cylindrical in shape with four fiberglass hoops, a 50.8-cm diameter, and a mesh netting of 2.54 cm (Memphis Net & Twine Co., Memphis, Tennessee, USA). Each trap was secured with 2 poles parallel to the mouth of the trap and a flotation device (e.g., a 2-liter plastic bottle or a pool noodle) was placed in the trap to ensure the turtles had access to air. All traps were set approximately 5 m apart and tied to riparian vegetation. Traps were baited with canned sardines placed in a perforated bait cup, and every third trap included a piece of romaine lettuce floating in the trap. Traps were checked every 24 hr. For all emydid turtles, straight-line carapace length (SCL), carapace width, plastron length, plastron width, and body depth were measured using tree calipers (Haglöf Inc., Madison, Mississippi, USA), and each individual received a uniquely identifying notching combination on the marginal scutes. Dorsal and ventral photographs were taken of every capture. If needed, additional photographs were taken to record abnormalities.

We examined photographs of all turtles post hoc to document visible abnormalities, including missing limbs, the presence of shell lesions, abnormal shell shape, and aberrant scutellation, as well as melanism in males. Shell lesions were classified as pitting in either the carapace or the plastron that differed in color and texture from the surrounding shell, often accompanied by irregular flaking around the margin of the pit. Abnormal shell shape included unusual shell morphology, such as shell curvature and deviation from typical shell outline. Abnormal scutellation included aberrant scute counts or arrangements on the carapace or plastron (Zangerl and Johnson 1957). Dovetail syndrome was classified as an abnormal arrangement of vertebral scutes where, instead of being linear, the scutes were arranged in a zig-zag pattern. “Other” abnormalities were categorized based on infrequent, unique occurrences, as well as those that were likely to have occurred postdevelopmentally, such as through predation or direct anthropogenic damage (Cummings et al. 2022). These abnormalities were classified based on recurring trends in a large number of our captures, as well as to allow comparison and to maintain consistency with the existing literature. We focused specifically on ontogenetic melanism in male T. s. elegans, which is characterized by a gradual increase in shell pigmentation in conjunction with a transition from the striped patterning on the head, neck, legs, and tail to dark and mottled skin (Cahn 1937; McCoy 1967; Lovich et al. 1990; Tucker et al. 1995; Hays and McBee 2009; Smith et al. 2016). In P. gorzugi, males in the study system often display reticulate melanism, whereby dendritic melanin deposition changes the traditional carapace pattern to form a netlike appearance (Bailey et al. 2005; Vaughan and Mali 2024).

We summarized our findings based on type of abnormality and calculated their relative proportions per site, including abnormal scutellation and dovetail syndrome, shell lesions, abnormal shell shape, and other visible abnormalities, as well as melanism in males. We also categorized turtles based on the number of different abnormality types per turtle, ranging from 1 abnormality type to 3 or greater. Turtles with multiple incidents of the same abnormality type (e.g., abnormal scutellation on both the carapace and plastron) were characterized as having a single abnormality type. Examining the number of different abnormality types per turtle could offer valuable insights into the diverse spectrum of health conditions that might be concealed when relying solely on the presence/absence of sublethal deformities.

Because of the low capture rates of P. gorzugi at each site, we were unable to conduct statistical analyses per species, so data were consolidated to include all abnormalities for both T. s. elegans and P. gorzugi. We used a Chi-square test of independence to assess whether the prevalence of physical abnormalities was equal across sites, where a turtle with 1 or more abnormalities, regardless of the type(s), was treated as an abnormal turtle. A Monte Carlo approximation for Fisher’s Exact Test with 10,000 simulations was used to determine if the presence of shell lesions for all captures differed among sites. Statistical significance was inferred at α = 0.05.

For each species, we calculated the proportions of carapace versus plastron scute abnormalities out of the total number of turtles with abnormal scutellation. We investigated patterns of anomalous scute locations (e.g., vertebral, costal, femoral, gular, marginal, nuchal, and abdominal scutes) by dividing the total number of turtles with each abnormal scute location by the total number of turtles with any type of abnormal scutellation. In the event that a scute was unable to be definitively characterized by location (e.g., Fig. 3A; an additional scute between 2 plastron plates), it was categorized as an additional carapace or plastral scute. We further analyzed patterns of plastron and carapace scute abnormalities for each species by dividing turtles into bins based on SCL. The prevalence was calculated based on the total number of turtles with abnormalities divided by the total number of turtles per species in each size class.

RESULTS

We captured 674 unique emydid turtles: 618 (92%) Trachemys scripta elegans and 56 (8%) Pseudemys gorzugi (Table 1). Because of low capture rates of yellow mud turtles (Kinosternon flavescens, n = 29), and incomplete data (i.e., not every turtle was measured and photographed) for Texas spiny softshell turtles (Apalone spinifera emoryi) and common snapping turtles (Chelydra serpentina), these species were removed from analysis. We did not capture any painted turtles (Chrysemys picta belli).

Table 1. The number of unique Rio Grande cooters (Pseudemys gorzugi) and red-eared sliders (Trachemys scripta elegans) captured at each of the 16 survey locations in Eddy County, New Mexico, in 2020 and 2021, as well as the number of individuals of each species displaying at least 1 abnormality. Sites were numbered from the most upstream site below Brantley Reservoir to the most downstream site above Red Bluff Reservoir.

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Of all emydid captures, 38% were female (3% P. gorzugi and 35% T. s. elegans), 58% were males (5% P. gorzugi and 53% T. s. elegans), and 4% were juveniles (0.3% P. gorzugi and 4% T. s. elegans). We observed turtles with abnormal scutellation (including dovetail syndrome), shell lesions, and abnormal shell shape (e.g., missing portions of the carapace and plastron, indentations, and kyphosis). Other abnormalities included deformities of facial features (e.g., missing eye and deformed nose) and appendages (e.g., missing tails, legs, and claws), anthropogenic damage (e.g., propeller injuries, fishhook ingestion, and bullet holes), and missing limbs (Figs. 1–4). Of 56 P. gorzugi captures, 29 (52%) exhibited at least 1 abnormality type, with 7 turtles (13%) exhibiting multiple abnormality types, of which 2 (4%) had 3 or more abnormality types. Of 618 T. s. elegans captures, 312 turtles (51%) had at least 1 abnormality type, with 8 turtles (14%) exhibiting more than 1 abnormality type: 226 (37%) had 1 type of abnormality, 72 (12%) had 2 types of abnormalities, and 14 (2%) had 3 or more abnormality types.

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Twelve sites (75%) had every type of abnormality recorded. The most upstream site, located in a remote area between the Brantley Reservoir and the city of Carlsbad, had the lowest prevalence of T. s. elegans with at least 1 abnormality type (22%). The most urbanized site (site 2; Table 1), located within the city of Carlsbad, had the highest prevalence of T. s. elegans with at least 1 abnormality type (69%), as well as the greatest proportion of T. s. elegans with 3 or more abnormality types in a single turtle (15%). There were no apparent trends between site location and the abnormality type for P. gorzugi. Per site, shell lesions were the most common abnormality documented in P. gorzugi (mean = 21%) and T. s. elegans (mean = 32%; Table 2). In addition, Trachemys s. elegans displayed shell lesions at all sites. When combining all abnormalities for both species, the Chi-square test of independence showed significant intersite variation in abnormality prevalence (χ²₁₅ = 41.0, p < 0.01). For shell lesions, the Monte Carlo simulation with Fisher’s Exact Test also showed significant intersite variation in prevalence (p < 0.01).

Table 2. A summary of prevalence (i.e., percentage) of physical abnormalities and melanism per site in Rio Grande cooters (Pseudemys gorzugi) and red-eared sliders (Trachemys scripta elegans) inhabiting the lower Pecos River in Eddy County, New Mexico. The “Other” category includes missing limbs, deformities of facial features and appendages, and anthropogenic shell damage (e.g., propeller injuries and bullet holes).

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Across all sites, 16% of all P. gorzugi captures and 12% of all T. s. elegans captures had at least 1 scute abnormality. Dovetail syndrome was not documented in any P. gorzugi captures, while the mean prevalence of dovetail syndrome per site in T. s. elegans was 6% (Table 2). Among the T. s. elegans with abnormal scutellation, scute abnormalities involving the carapace were greater than the plastron (82% and 21%, respectively), with some individuals having abnormalities in both locations. Pseudemys gorzugi had greater prevalence of plastron than carapace scute abnormalities (67% and 33%, respectively). In P. gorzugi, abnormal scutes involving the vertebral (33%) and femoral (11%) scutes were recorded, and 56% were documented with additional plastral scutellation. In T. s. elegans, abnormal scutellation of the vertebral scutes was most frequently documented (71%), followed by additional plastral scutes (17%), as well as abnormal costal (8%), marginal (3%), gular (1%), nuchal (1%), and abdominal scutes (1%). For both the carapace and plastron, the majority of scute anomalies were attributed to supernumerary scutes (Paul et al. 2022). Slight variations in the frequency of scute abnormalities were seen across size classes (Fig. 5). For T. s. elegans, carapace abnormalities were more prevalent across all size classes than plastron abnormalities, with plastron abnormalities being documented in larger size classes. In P. gorzugi, carapace abnormalities were documented in only a single size class, with plastron abnormalities being more frequent across most size classes.

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Overall, only ∼4% of turtles were juveniles. Pseudemys gorzugi captures were documented at 11 sites. Two P. gorzugi juveniles were captured at 2 locations (sites 6 and 11; Table 1), which comprised 9% and 50% of total P. gorzugi captures at these sites, respectively. Trachemys s. elegans was captured at all 16 sites, and of 10 sites with juvenile captures, proportion of juveniles ranged from 2% to 15%.

Melanism was documented in both P. gorzugi and T. s. elegans (Fig. 6). Specifically, the mean proportions of melanistic P. gorzugi and T. s. elegans males per site were 10% and 32%, respectively (Table 2). Melanistic males per site ranged from 0% to 71% for P. gorzugi and from 0% to 59% for T. s. elegans. For T. s. elegans, > 40% of males were melanistic at 5 sites.

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DISCUSSION

We provide an overview of the types and frequencies of physical abnormalities in emydid turtles on the lower Pecos River, which illustrates the importance of further study on the assessment of multiple environmental stressors impacting the freshwater turtle community. Many existing studies have focused on abnormalities in hatchling turtles (e.g., Bishop et al. 1998; Zimm et al. 2017), but because high adult survivorship is particularly important for the persistence of turtle populations, focusing on anomalies in adults may be more indicative of the ecosystem health and long-term population sustainability. This concern is especially important in the case of abnormalities that may appear later in life and not only during embryonic development. One of the most notable outcomes of this study is the variety of observed abnormalities and the high cumulative prevalence at which they occur, as well as the widespread occurrences across all study sites.

The lower Pecos River exhibited a high overall frequency of turtles with at least 1 abnormality (i.e., approximately 50% for both species), which is nearly twice as great as the values reported in populations of other emydids (i.e., midland painted turtles), and 2 to 13 times greater than values seen in common snapping turtle populations (de Solla et al. 2008; Davy and Murphy 2009). The mean proportion of each abnormality per site was higher for T. s. elegans, except for abnormal scutellation (Table 2). The maximum percentage of individuals with shell lesions and dovetail syndrome was greater in T. s. elegans, but for all other abnormalities, as well as melanism, P. gorzugi had a greater maximum percentage per site (Table 2). Total abnormalities and shell lesions both varied in prevalence among sites, implying that site-specific environmental and land use factors may play an important role in the prevalence of abnormalities. This idea is further supported by the high prevalence of abnormalities in T. s. elegans at the most urban site, although further study is needed to explore these relationships explicitly. Given riverine turtles’ longevity and ability to make occasional long-distance movements (MacLaren et al. 2017; Sirsi et al. 2025), the causative agents of the abnormalities may not be tied to the precise location of their capture and current abnormalities may be indicative of historic stressors, which makes determining precisely when and where these abnormalities developed obscure.

Shell lesions were the most common abnormality in our study for both species, documented in 36% of P. gorzugi and 31% of T. s. elegans overall. Lesions were found on both the plastron and carapace, with lesions documented in both melanistic and non-melanistic males. Out of all P. gorzugi males with shell lesions, 42% were melanistic, and for all T. s. elegans males with shell lesions, 54% were melanistic. A notable challenge in studying shell lesions is the difficulty in discerning causal infectious agents as opposed to opportunistic secondary infections that form because of mechanical shell injury, including bacterial infections of the shell and the skin (Hernandez-Divers et al. 2009; Aleksić-Kovačević et al. 2014). Although shell swabs were not taken during surveys, the high incidence of lesions may suggest symptoms of infectious agents, such as Emydomyces testavorans (Woodburn et al. 2019, 2021; Lambert et al. 2021) or filamentous algae (Christiansen et al. 2020), that warrant future investigation. Incorporating disease assessments may assist in providing a more objective technique to discern lesions from natural mechanical abrasions. It is possible that various causative agents are working in conjunction with one another and synergistically affecting freshwater turtles in our study system. In the context of a degraded river system like the lower Pecos River, the high prevalence of shell lesions may be connected to contaminant exposure.

Previous studies reported abnormal scutellation as the most frequently recorded abnormality (Bell et al. 2006; Davy and Murphy 2009). In our study, abnormal scutellation was the second most common abnormality for both species. The rates were similar to those seen in other emydids, such as painted turtles in Ontario, Canada, and Illinois, USA, but it was markedly higher than those reported for common snapping turtles in Pennsylvania, USA (Bell et al. 2006; Davy and Murphy 2009; Telemeco et al. 2013). The high incidence of scute abnormalities in our study may be indicative of frequent environmental fluctuations during embryonic development (MacCulloch 1981), which could occur as a result of the ongoing drought in the American Southwest and could reasonably have impacted incubation conditions of adult turtles captured, given that the drought has occurred over a multidecadal timescale (Williams et al. 2022). The majority of scute abnormalities documented were generated by the division or addition of scutes, a trend that has been documented elsewhere (MacCulloch 1981; Bujes and Verrastro, 2007). Aberrant scute patterns involving the vertebral scutes seem to be disproportionately more common among our captures, with 71% of T. s. elegans and 33% of P. gorzugi with abnormal scutellation documented to have aberrant vertebral scutes. The fusion of paired primordia to form the vertebral scutes is particularly sensitive to environmental noise at mid-developmental stages, and the mechanism may be less stable at higher temperatures (Zimm et al. 2017; Maffucci et al. 2020; Cordero et al. 2023). Trachemys s. elegans had a slightly greater percentage of carapace scute abnormalities, while P. gorzugi had more plastron scute abnormalities. Similarly, Smith et al. (2020) documented variation among species in the frequency of plastron and carapace abnormalities, but they documented no difference between carapace and plastron abnormalities in T. s. elegans.

We encountered 2 P. gorzugi with extreme cases of abnormal shell shape (Fig. 3C), which has been attributed to dry incubation conditions or chemical exposure (Lynn and Ullrich 1950; Nagle et al. 2018, 2023). Our observations also revealed a single instance of boat propeller damage on the carapace of a T. s. elegans at the most urbanized site. Anthropogenic recreation-induced injuries have been documented in freshwater turtles (Galois and Ouellet 2007; Heinrich et al. 2012; Bennett and Litzgus 2014; Smith et al. 2018), with higher frequencies of boat propeller strikes often reported in females, likely because of sex-specific body size, habitat use, and thermoregulatory needs (Bulté et al. 2010; Bennett and Litzgus 2014; Seburn et al. 2023). These types of injuries can reduce body condition and survivorship (Cecala et al. 2009), with the potential to alter community structure (Smith et al. 2006) and increase the likelihood of extirpation (Bulté et al. 2010).

In our study, the mean proportions of melanistic males per site for T. s. elegans and P. gorzugi were 32% and 10%, respectively. Although not an abnormality, the high prevalence of melanistic males, particularly for T. s. elegans, coupled with the low proportion of juvenile turtles (comprising 4% of T. s. elegans captures and 0.3% of P. gorzugi captures across all sites), likely indicate low recruitment and aging populations. At a community level, this finding could potentially represent an extinction debt (Figueiredo et al. 2019), where older individuals persist with a variety of sublethal abnormalities while more vulnerable juveniles struggle to survive to adulthood. Interestingly, the downstream-most site had the highest proportion of T. s. elegans juveniles and was also a site where flow may have been supplemented by the upstream convergence with the Delaware River. Similarly, 1 of the 2 juvenile P. gorzugi was found below the Pecos River confluence with the Black River.

The present study is an important step in identifying the broad spectrum of sublethal abnormalities expressed in freshwater turtles and understanding their prevalence in a highly altered river system. A notable challenge to comparing abnormalities across different studies is the subjectivity in categorizing different abnormalities, with comparisons drawn from a limited number of studies varying in spatial and temporal scales with unique environmental stressors. Nevertheless, the frequency and types of abnormalities on the lower Pecos River are extreme, particularly in the context of previous research. Additional research is needed to refine our understanding of the causes of these abnormalities. Future studies should explore the impacts of sublethal abnormalities on long-term population persistence, including consequences to fitness and recruitment, especially in the context of environmental contamination. Integrating the analysis of sublethal abnormalities with measurements of stress hormones (e.g., corticosterone), clutch size, female body size, and the locomotor performance (e.g., swimming ability and righting response), growth rates, and body size of hatchlings may be particularly valuable (Booth et al. 2004; Delmas et al. 2007; Le Gouvello et al. 2020). Public outreach campaigns that provide educational materials and signage may be an important tool to mitigate harmful activities, such as the shooting of turtles, that may exacerbate the fitness consequences of physical abnormalities (Pierce et al. 2016; Suriyamongkol et al. 2019). We also suggest more unified standards and terminology used to quantify the extent of these abnormalities. Ultimately, studying physical abnormalities in freshwater turtles is a crucial step in recognizing populations in need of conservation and management and we encourage researchers to routinely report incidence of abnormalities during surveys.