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Record Size Chelydra serpentina (Snapping Turtle) from Florida’s Freshwater Springs
Andrew D. Walde, Eric C. Munscher, and Angela M. Walde

Southeastern Naturalist, Volume 15, Issue 2 (2016): N16–N22

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2016 Southeastern Naturalist Notes Vol. 15, No. 2 N16 A.D. Walde, E.C. Munscher, and A.M. Walde Record Size Chelydra serpentina (Snapping Turtle) from Florida’s Freshwater Springs Andrew D. Walde1,2,*, Eric C. Munscher1,3, and Angela M. Walde2 Abstract - We present data on large Chelydra serpentina (Snapping Turtle) from 4 freshwater springs in Florida located in Wekiwa Springs, Volusia Blue Spring, Peacock Springs, and Manatee Springs state parks. Several of the turtles captured at Wekiwa Springs and Volusia Blue Springs are larger than the previous Florida record for this species. In the past, Snapping Turtles in Florida have been considered a distinct species or a clearly defined subspecies, however, recent genetic techniques have shown that they are not well-differentiated evolutionary lineages, and therefore Snapping Turtles in Florida are not unique from those in the rest of the range. These large southern individuals do not follow the expected trend of decreasing size with decreasing latitude. The nature of spring environments, particularly the warm, constant temperatures which facilitate year-round growth appears to be producing record-sized Snapping Turtles in Florida when compared to other Florida localities. Additional studies should investigate the chelonian communities in Florida’s spring habitats to determine if these special environments are producing unique populations. For ectotherms, growth rate, physiological performance, reproduction, and survivorship, are all constrained by their physical environment. In turtles, growth rate and adult size are both directly linked to increased reproductive output and survivorship (Congdon and Gibbons 1985, Congdon and van Loben Sels 1991, Dunham and Gibbons 1990, Iverson and Smith 1993) and one would expect that turtles in warmer climates would have greater growth rates and adult body size. The reason for the increased growth rates and larger body size of chelonians from warmer conditions is not due solely to temperature per se; rather, it is thought to be promoted by increased productivity at warmer sites that contributes to dietary shifts (Gibbons 1970). Although greater growth rates have been documented from warmer conditions (Gibbons 1970, Williamson et al. 1989), female adult-turtle body size is correlated with latitude or frost-free days, with larger individuals at more northern localities (Iverson et al. 1997, Walde et al. 2003). While this pattern is evident in Chelydra (snapping turtles), it does not hold for female turtles from the tropics; tropical Chelydra are as large as the most-northern females (Iverson et al 1997), suggesting that there is something about the growth conditions of these more tropical Chelydra that allows them to achieve greater body size. Chelydra serpentina L. (Snapping Turtle) is a large aquatic species native to North America. Its range extends across southern Canada, the eastern and central regions of the US, south to Florida and the gulf coast, and west into parts of Texas—one of the broadest ranges of any North American turtle (Ernst and Lovich 2009). This species has been studied extensively in the northern parts of its range, yet very little is known about it within the southern portion of its range, which includes most of Florida. Until recently, Florida Snapping Turtle populations were considered members of a well-defined subspecies (Chelydra serpentina osceola). However, Shaffer et al. (2008) argued that the molecular data implied that C. s. osceola and C. s. serpentina are not well-differentiated evolutionary lineages and 1Turtle Survival Alliance – North American Freshwater Turtle Research Group, 1989 Colonial Parkway, Fort Worth, TX 76110. 2Walde Research and Environmental Consulting, 8000 San Gregorio Road, Atascadero, CA 93422. 3SWCA Environmental Consultants, Department of Natural Resources, 207 Bursca Drive, Bridgeville, PA 15017. Corresponding author - Manuscript Editor: Max Nickerson Notes of the Southeastern Naturalist, Issue 15/2, 2016 N17 2016 Southeastern Naturalist Notes Vol. 15, No. 2 A.D. Walde, E.C. Munscher, and A.M. Walde therefore, C. s. osceola should be abandoned. This designation is accepted by the Turtle Taxonomy Working Group (2014) and thus, all specimens in Florida are considered Chelydra serpentina. Snapping turtles are sexually dimorphic; males are generally larger than females (Ernst and Lovich 2009). In Florida, this species is most commonly found in small creeks, ponds, floodplain swamps, spring-fed creeks and rivers, roadside ditches, and other habitats that offer a soft bottom in which to hide (Meylan 2006). The majority of the Florida studies have concentrated on pond, lake, canal, and river systems (Aresco and Gunzburger 2007; Bancroft et al. 1983; Johnston et al. 2008, 2012). Few researchers have examined populations of Snapping Turtles within spring environments. Here we report on several large Snapping Turtles from spring systems throughout Florida, including several specimens larger than the state record. The previous Florida state record was an individual caught on 16 November 1928 at a locality simply listed as “Apopka, FL” that had a maximum carapace length (CLmax) of 424 mm ([UF] #66157; K. Krysko, Florida Museum of Natural History, University of Florida, Gainesville, FL, pers. comm; Meylan 2006). Historic museum specimens often listed vague collection localities, and collection information was frequently submitted on hand-written notes (K. Krysko, pers. comm.). Wekiwa Springs is less than 5 km from downtown Apopka; thus, this historic record could possibly be from Wekiwa Springs. The Turtle Survival Alliance–North American Freshwater Turtle Research Group (NAFTRG) has been monitoring turtle populations in 8 state park springs in Florida, at some sites for as long as 16 years. We occasionally capture Snapping Turtles during our long-term turtle assemblage/population study at Wekiwa Springs State Park (WSSP; Orange and Seminole counties, FL). We have captured thousands of turtles at this site over the past 16 years, but only 20 individual Snapping Turtles to date. Habitat complexity could be a cause for our low capture-rate for this species. Wekiwa Springs has a thick detritus layer at the bottom of the lagoon and run that could aid in this species’ cryptic camouflage and hiding abilities (Munscher et al. 2015b). We captured and marked 20 Snapping Turtles at WSSP between 2000 and 2015. Over 65% (n = 13) had CLmax > 360 mm. Five individuals at WSSP were larger than the current state record (Table 1). We captured the largest turtle on 12 August 2014; it represents a new Florida state record (UF # 173686; Fig. 1): CLmax = 448 mm (Table 1, Fig. 1), 24 mm greater than the previous state record (old record = UF #66157; K. Krykso, pers. comm.). At Volusia Blue Springs State Park (VBSSP) in Volusia County, FL, we captured an adult male with CLmax = 436 mm, exceeding the historic state record by 12 mm (Table 1). Although not a record-sized Snapping Turtle, our largest capture at Wes Skiles Peacock Springs State Park (PSSP), Suwannee County, FL, was 389 mm CL. Our largest capture at Manatee Springs State Park (MSSP), Levy County, FL, had a CLmax of 390 mm and weighed 12.1 kg (Table 1). Our discovery of several large Snapping Turtles, including record-sized individuals in spring systems in Florida was somewhat surprising. Numerous projects have been conducted in these spring habitats, and naturalists and herpetologists favor them as areas to visit; however, little to no work has been done on the turtle communities in these springs (Hrycyshyn, 2006). Interestingly, it is well documented that body size in Snapping Turtles increases with increasing latitude and elevation (Iverson et al. 1997, Moll and Iverson 2008); therefore, one would expect smaller turtles in northern and central Florida. Our observations of uncharacteristically large-sized Snapping Turtles are similar to reports from the Santa Fe River in northwestern peninsular Florida, where Johnston et al. (2012) 2016 Southeastern Naturalist Notes Vol. 15, No. 2 N18 A.D. Walde, E.C. Munscher, and A.M. Walde Figure 1. Record Chelydra serpentina captured at Wekiwa Springs State Park 12 August 2014 (FLMNH record # 173686). This male had a carapace length of 448 mm and weighed 22.7 kg. (Photograph © Nicole Salvatico). Table 1. Morphometrics of the largest Chelydra serpentina (Snapping Turtle) from 4 springs in Florida. Previously published data from 3 non-spring habitats (pond, canal, and lake) are included for comparison. We calculated values from size graphs in the publication because the sizes of largest animals were not listed. WSSP = Wekiwa Springs State Park, VBSSP =Volusia Blue Springs State Park, PSSP = Wes Skiles Peacock Springs State Park, MSSP = Manatee Springs State Park, and CL = carapace length. CL Weight Survey site System Sex (mm) (kg) Record WSSP Spring ♂ 425 13.6 This study WSSP Spring ♂ 430 17.5 This study WSSP Spring ♂ 438 18.9 This study WSSP Spring ♂ 441 18.2 This study WSSP Spring ♂ 448 22.2 This study ; New Florida Record: FLNHM #173686 VBSSP Spring ♂ 436 26.0 This study PSSP Spring ♂ 389 12.5 New County Record: FLMNH 168690; Munscher et al. 2013 MSSP Spring ♂ 390 12.1 This study McCord Pond, Leon County, FL Pond ♂ 360–379 Aresco et al. 2006 Broward County, FL Canal ♂ 321 Johnston et al. 2008 system Lake Conway, Orange County, FL Lake ♂ 330–339 Bancroft et al. 1983 N19 2016 Southeastern Naturalist Notes Vol. 15, No. 2 A.D. Walde, E.C. Munscher, and A.M. Walde studied Snapping Turtles in that system and captured 105 turtles of which 46 were adult males. Almost 60% (n = 27) had a CL > 360 mm. These authors hypothesized 3 reasons for the large sizes they observed: (1) as bottom walkers in a fast current, they may need to be larger to facilitate movement; (2) turtles may be larger to survive agonistic encounters with the sympatric Macrochelys suwanniensis Thomas, Granatosky, Bourque, Krysko, Moler, Gamble, Suarez, Leone & Roman (Thomas et al. 2014) (Alligator Snapping Turtle); and (3) growth conditions are optimal in the habitat they studied. Our observations from several different springs provide a perspective on these 3 hypotheses. If the turtles are larger to facilitate movement in the fast current, the currents in our studies should be similar or stronger than the current in Johnston et al.’s (2012) study. The Santa Fe River is fed by 21 artesian springs (of varying magnitude) in addition to upstream flow, which would suggest a high volume of water. Although Johnson et al. (2012) do not report current velocity of the Santa Fe River, the authors commented that the current increased in downstream reaches. Wekiwa Springs is a second-magnitude spring with a long-term average-flow rate of 20.9 m/s; Volusia Blue Spring is a first magnitude spring with a recent flow rate of 26.5 m/s, but a long-term average of 49.4 m/s; and Manatee Springs (first magnitude) has a long-term average of 54 m/s (Scott et al. 2004). Because Wekiwa Springs has the largest Snapping Turtle specimens and has the lowest flow rate, it seems unlikely that the large Snapping Turtles observed by us and by Johnson et al. (2012) represented an evolutionary response due to flow rates. Snapping Turtles in the Santa Fe River region of Florida may tend to grow larger in order to deal with direct competition with the much larger Alligator Snapping Turtle or even to avoid direct predation by this species. Additionally, when they examined their samples from different habitats, Johnston et al. (2012) noted that they captured smaller Snapping Turtles in spring habitats along the Santa Fe River. The authors suggested that smaller Snapping Turtles might occupy these springs to avoid predation because the Alligator Snapping Turtles were not found in this habitat type during their study. However, our data does not support this hypothesis. WSSP and VBSSP do not overlap with the Alligator Snapping Turtle’s range, therefore the threat of predation or agonistic encounter between the 2 species is not present at our sites. Furthermore, our Snapping Turtles are from pure spring systems, yet have the largest (record-size) individuals, contrary to what Johnson et al. (2012) observed. Snapping Turtles may increase in size in Florida due to predatory pressure from a different species: Alligator mississippiensis (Daudin) (American Alligator). We have observed several species of turtles, including large Snapping Turtles, being eaten by American Alligators (Fig. 2). Some Snapping Turtles had circular puncture holes (healed) in the carapace that may have been caused by American Alligators. However, although predation may have some influence, if American Alligators were the causal agent of the larger Snapping Turtles, we would expect that all states with range overlap between the 2 species—from east Texas to North Carolina—would also have larger Snapping Turtles, but this is not the case. Some populations in Florida have much smaller individuals (Aresco and Gunzburger 2007, Bancroft et al. 1983). Since it seems unlikely that predatory pressures and water flow are the driving forces leading to large Snapping Turtles, it is plausible that something about these spring systems is a factor. The final hypothesis suggested by Johnson et al. (2012) was that optimal growth conditions provided by the springs might be the primary cause of development of larger Snapping Turtles; however, they had no data from Snapping Turtles in other spring systems to validate or compare with their results. The springs of Florida are considered hotspots 2016 Southeastern Naturalist Notes Vol. 15, No. 2 N20 A.D. Walde, E.C. Munscher, and A.M. Walde of biodiversity (Hubbs 1995). Water temperature in Wekiwa, Volusia Blue, and Manatee Springs is approximately 22–23 °C all year (Scott et al. 2004), and in the Santa Fe River, temperatures fluctuate by 4 °C between 21 and 24 °C (Johnston et al. 2012). Turtles from warmer habitats have been shown to have greater growth rates and larger body size than those from cooler conditions (Gibbons 1970, Williamson et al. 1989). These warm, constant temperatures provide ideal growing conditions for aquatic turtles, and a long growing season for plants and algae, as well as a long active period for other fauna, thus providing the potential for year-round food availability (Munscher et al. 2015a). Although activity of Snapping Turtles has not been studied in these spring systems, year-round activity of Snapping Turtles has been observed just south of our study areas (Bancroft et al. 1983); and hence, springs may provide a much longer growing season in comparison to what is available in most other habitats. Tropical Chelydra are known to be as large as the largest northern species (Iverson et al. 1997). The spring environment at our study site is similar to more-tropical regions where Chelydra have year-round growing conditions. We have shown that multiple springs in north and central Florida support large Snapping Turtles, leading us to conclude that optimal growth conditions in these springs are responsible for their large size. These spring-dwelling Snapping Turtles are larger than individuals from other Florida habitats: Lake Conway (n = 19), McCord Pond (n = 59), and a canal system (n = 52), as noted in Table 1 (Aresco et al. 2006, Bancroft et al 1983, Johnson et al. 2008). These results suggest further inquiries into the growth and dynamics of turtles inhabiting these spring systems, which appear to be quite unique. Figure 2. An ~3–3.5-m Alligator mississippiensis (American Alligator) carrying a large Chelydra serpentina (Snapping Turtle) in Rock Springs, Orange County, FL, ~10 river km northeast of Wekiwa Springs State Park. (Photograph © Joanne Bolemon). N21 2016 Southeastern Naturalist Notes Vol. 15, No. 2 A.D. Walde, E.C. Munscher, and A.M. Walde Acknowledgments. The Turtle Survival Alliance–North American Freshwater Turtle Research Group (NAFTRG) express our gratitude to all of the volunteers who have joined us over the past 16 years. We thank Kenneth Krysko at the Florida Museum of Natural History for information on the historic record and cataloguing our current observations. We are grateful to Ben Williams, Jessy Wales, Brian Bowers, Kelly Adkins, and Nicole Salvatico for help in capturing and processing the new record turtle. We thank Nicole Salvatico and Joanne Bolemon for providing photographs, and Wekiwa Springs State Park, Megan Keserauskis with the FWC, Virginia Oros and Deborah Shelly from the Wekiva River Aquatics Preserve, staff of Manatee and Peacock Springs State Parks, the Friends of the Wekiva River, Wekiva Wild and Scenic River System Management Committee, Wekiva River Aquatic Preserve, Wekiva Wilderness Trust, and Keep Seminole Beautiful for their constant support and much needed funding. 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