Pseudemys Concinna Research Articles

Food Habits and Selective Foraging by the Texas River Cooter (Pseudemys texana) in Spring Lake, Hays County, Texas

The fall-winter food habits of the Texas river cooter (Pseudemys texana) were investigated at Spring Lake, Hays County, Texas, by examination of stomach contents. Samples were collected from 33 live turtles by flushing stomach contents with water (Fields et al., 2000). Four aquatic macrophytes composed 91.6% of the diet. Aquatic macrophyte availability at Spring Lake was estimated using the Daubenmire technique (Daubenmire and Daubenmire, 1968) and compared to occurrence in the diet to assess selectivity in foraging. Cooters actively selected Carolina fanwort (Cabomba caroliniana), a plant low in fiber and high in total digestible nutrients. Hydrilla (Hydrilla verticilata), an invasive exotic aquatic plant, was an important food item due to the large amount present in the lake. The Texas river cooter, Pseudemys texana (Ward 1984), is a freshwater basking turtle of the family Emydidae. It is endemic to the Brazos, Colorado, Guadalupe, and San Antonio river basins of central and south Texas. Rivers, streams, and nearby ponds, especially those with abundant aquatic vegetation and basking sites, are preferred habitats ((??)Vermersch, 1992). It also is found in man-made impoundments, irrigation ditches, canals, and cattle tanks (Carr, 1952). Prior to Seidel and Smith (1986), some species of Pseudemys were included in the genus Chrysemys (Carr, 1952; McDowell, 1964; Zug, 1966; Weaver and Rose, 1967). In addition, P. texana was included within other species of Pseudemys, until it was recognized as a distinct species by Ward (1984). An early study of the food habits of P. texana (Strecker, 1927) found only mollusks (Sphaerium sp., Planorbis sp., and Lymnaea sp.) in the digestive tracts. Young P. texana have been observed to pursue insects, crayfish, and other invertebrates ((??)Vermersch, 1992). Other members of the genus are presumed to consume more invertebrates when young and become less carnivorous with maturation (Ernst and Barbour, 1989; Vermersch, 1992; Ernst et al., 1994). In general, P. texana is considered to be herbivorous when mature, although quantitative analysis of the diet is lacking. Analysis of stomach contents can provide informa- tion about which food items are palatable, nutritious, or abundant in the environment (Ward and Keith, 1962). Many herbivores have been shown to select plants based on their nutrient content (Gwynne and Bell, 1968). Consumption of a dietary component dispropor- tionate to its availability in the environment would suggest selectivity in foraging (Johnson, 1980). Al- though, the nutritional quality of plants is important to herbivores, important food plants also may be eaten in proportion to their availability without selection. Knowledge of food habits and foraging selectivity of P. texana is essential to the thorough understanding of how this species functions within its habitat and how it may influence the structure of the ecosystem. The objectives of this study were to describe the fall-winter food habits of P. texana at Spring Lake, Hays County, Texas; to determine if P. texana foraged selectively by comparing usage to availability in the environment; and to compare the nutritional quality of major components of the diet.

Reproduction of the River Cooter, Pseudemys concinna, in Arkansas and across Its Range

Reproduction of the River Cooter, Pseudemys concinna, in Arkansas and across Its Range

Resource use of five sympatric turtle species: effects of competition, phylogeny, and morphology

I quantified resource use with respect to habitat, diet, and diel and seasonal use of basking time for five sympatric turtle species in a cove on Kentucky Lake, an impoundment of the lower Tennessee River in western Kentucky, U.S.A. I used pseudocommunity analyses to test for significant structure in resource use, compared resource-use matrices with matrices representing phylogenetic similarity, and measured morphological characteristics related to resource use. Three strictly riverine species (Graptemys pseudogeographica, Graptemys ouachitensis, and Apalone mutica) with relatively long limbs and digits used outer portions of the cove near deeper waters to a greater extent than did two shorter-limbed species (Trachemys scripta and Pseudemys concinna), which inhabit both lotic and lentic waters. Only the difference in habitat between A. mutica and the other four species was shown to be significant in pseudocommunity analysis, a result that can be better explained by differences in basking substrates than by competition. Dietary studies indicated two guilds, omnivore and algivore, in spite of the low pairwise overlap values that resulted from overall prey diversity. Analysis of use of diel and seasonal basking time revealed significant structure (partitioning) at only the rank of second-nearest neighbor for seasonal time. Clustering phenograms for resource similarity among the five species were overall highly similar to two phylogenetic hypotheses. Phylogeny was thus shown to be of greater importance in structuring resource use in Kentucky Lake than interspecific competition. In addition, the similarity in clustering phenograms was not consistent with the hypothesis of niche complementarity, suggesting that interspecific competition was of little importance.

Variation in Shell Arching and Sexual Size Dimorphism of River Cooters, Pseudemys concinna, from Two River Systems in Alabama

LYNCH, M. 1991. Analysis of population genetic structure by DNA fingerprinting. In T. Burke, G. Dolf, A. J. Jeffreys, and R. Wolff (eds.), DNA Fingerprinting: Approaches and Applications, pp. 113-126. Birkhauser Verlag, Basel, Switzerland. PARKER, P. G., A. A. SNOW, M. D. SCHUG, G. C. BooTON, AND P. A. FUERST. 1998. What molecules can tell us about populations: choosing and using a molecular marker. Ecology 79:361-382. PFENNIG, D. W. 1997. Kinship and Cannibalism. Bioscience 47:667-675.

Aggressive Interactions during Basking among Four Species of Emydid Turtles

-I observed 123 instances of aggression in 100.7 h among basking emydid turtles (Trachemys scripta, Pseudemys concinna, Graptemys pseudogeographica, and G. ouachitensis). No consistent pattern occurred in heterospecific interactions with regard to outcomes. Larger turtles (i.e, caused or resisted displacement) in 70% of all interactions, and initiators won 80%; in all, 61% were won by larger, initiating turtles. Larger turtles displaced smaller turtles into the water more often than the reverse. Larger turtles also elicited avoidance behaviors from smaller turtles that were not elicited from larger turtles by smaller turtles. The hypothesis that smaller turtles assess and avoid larger turtles was suggested by (1) the lower rate of initiation by smaller turtles, (2) the turning away response that was observed only in smaller turtles, and (3) the fact that smaller turtles sometimes voluntarily displaced themselves when larger turtles emerged from the water or advanced toward them on a substrate, but the reverse was not observed. Alternatively, inherent aggressiveness may be a function of body size in these species. l erpetology, Vol. 3 , No. 2, p . 214-219, 1999 1999 Society for the Study of Amphibians and Reptiles i e I teractions during Basking among Four Species of tles Aquatic emydid turtles are noted for basking on logs and branches that project from the water (Boyer, 1965). Basking behavior is primarily a thermoregulatory behavior but may also serve to rid turtles of skin parasites and epizootic algae and to promote vitamin D synthesis (Boyer, 1965; Moll and Legler, 1971; Vogt, 1979). Aggressive competition for space may occur among basking turtles if basking substrates are 3 Present Address: Division of Biological Sciences and Related Technologies, Madisonville Community College, 2000 College Drive, Madisonville, Kentucky 42431 USA. E-mail: LPeterO@pop.uky.edu limiting. While many authors have commented on the seeming lack of aggression among basking emydid turtles (Boyer, 1965; Ernst, 1971; Waters, 1974; Vogt, 1980), several studies have documented aggressive behavior between conspecifics, including open-mouth gestures, biting, and various forms of pushing (Bury and Wolfheim, 1973; Auth, 1975; Bury et al., 1979; Lovich, 1988; Pluto and Bellis, 1986). Limited data show that similar aggressive interactions also occur between basking heterospecifics (Auth, 1975; Lovich, 1988; Lindeman, 1996). Body size may play a role in determining the outcome of aggressive interactions. Larger Grap214 This content downloaded from 207.46.13.169 on Sat, 01 Oct 2016 05:42:45 UTC All use subject to http://about.jstor.org/terms AGGRESSION AMONG BASKING EMYDIDS temys geographica displaced smaller conspecifics more often than the converse (Pluto and Bellis, 1986), and in three cases of interspecific aggression, the larger turtle displaced the smaller turtle (Auth, 1975). Avoidance behavior in Clemmys marmorata was also size dependent (Bury and Wolfheim, 1973). I observed interactions of basking turtles in a mixed-species assemblage in a riverine reservoir in western Kentucky. The objectives of my study were to determine whether (1) some species have a consistent advantage over other species in competition for basking space; (2) relative body size predicts the outcome of interactions in a mixed-species assemblage; and (3) initiators tend to win interactions (i.e., cause or resist displacement) more frequently than recipients of interactions. MATERIALS AND METHODS During 1992-1994, I used a spotting scope with 22-60x zoom magnification to observe basking behavior of turtles using single basking substrates (logs and branches) or clusters of 14 substrates in three coves on Kentucky Lake, an impoundment of the lower Tennessee River: Nickell Cove (on 15 d), Jones Creek Cove (1 d), and a cove on the canal that connects Kentucky Lake with Lake Barkley (1 d). I observed turtles from early morning until late afternoon but terminated observation earlier for inclement weather or heavy recreational use of the area. The primary species observed were the emydids Trachemys scripta, Pseudemys concinna, Graptemys pseudogeographica, and G. ouachitensis. Notes on instances of contact or aggression among turtles were recorded using a hand-held tape recorder. I identified species involved and recorded the relative sizes of the two turtles if there was a discernible difference, with details about their interaction and its outcome. Individuals were classified as initiators or recipients of interactions.

Effect of Density on Predation Rate for Turtle Nests in a Complex Landscape

The relationship between the spatial distribution of turtle nest sites and nest predation was investigated in a landscape encompassing a 12-ha freshwater wetland in west-central South Carolina, USA. The goals of the study were to determine if nest predation is a function of nest density, and if two other spatial factors, habitat type and distance of nests from the wetland, influence survival rate. Gravid females of three turtle species (Kinosternon subrubrum, Pseudemys concinna floridana, and Trachemys scripta) inhabiting the wetland were monitored from the time they exited the wetland to nest until they returned from their nesting forays. A total of 145 nests were located during three nesting seasons (1992-1994). Nests were monitored from the day of oviposition until they were deemed to have successfully produced hatchlings or depredation was documented. The three-year mean predation rate was 84.2% (80%, 88%, and 81% for 1992, 1993 and 1994. respectively). Modeling of the point pattern of nest locations suggests that nests were distributed at varying densities and that density changed with habitat type and distance to the wetland. Logistic regressions of predation rates against two crowding indices demonstrate no significant evidence for density-dependent nest predation. Furthermore, autologistic regression provided no evidence indicating that nest survival is dependent on the survivorship of neighboring nests. Logistic regressions of predation rates against habitat type and distance from the marsh of origin suggest that predation rate is not a function of these two spatial characteristics. In , no evidence was found that linked predation rate to any of the spatial characteristics of nest distribution that were examined. The lack of density dependent nest predation is contrary to findings from some previous avian and chelonian studies, but supports the findings of other researchers. It is suggested that predation during the current study was either density independent or that any local density effects were masked by an ideal free distribution of turtle nests. Our data support the findings of several researchers that suggest density, as a single factor, is not a generalizable predictor of nest predation probability.

Reproduction in the Suwannee cooter, Pseudemys concinna suwanniensis

The Suwannee cooter, Pseudemys concinna suwanniensis, is the largest emydid turtle in North America. From 1988 to 1993, we studied the reproductive and nesting biology of a population of this turtle in the headwaters of the Wakulla River in northern Florida. Based on 239 marked females, we estimated a population of about 305 adult females in ca 5 km (41 ha) of river. Nesting females ranged in plastron length (PL) from 304 to 383 mm and in body mass from 4.5 to10.5 kg. We estimate that female body size at maturity varies by as much as 50 mm, with a mean size at maturity of ca 330 mm PL, or only about 1 cm less than the mean PL. The negligible post-maturational growth of adult females, coupled with their size range, suggests that sexual maturity is less a function of size than of age, which we estimate minimally at 10 years. Nesting begins in late March or early April and extends into early August. Females may lay as many as five or more clutches at intervals of approximately 16-25 days. Most, if not all, mature females nest annually. Nesting is diurnal and frequently coincides with rainfall. Typical clutches contain 8-27 eggs (mean 17.5). Average annual reproductive potential may approach 70 eggs, with a maximum for individuals of >100. Normal egg and hatchling sizes span ranges of 9.8-21.7 g and 6.8-14.6 g, respectively, and are, at most, only weakly correlated with female body size. Clutch mass tends to increase with body size, but relative clutch mass, which averages ca 0.05. does not. These results suggest this species is an egg number maximizer rather than an egg size optimizer. We estimate for the population an annual production of ca 26,700 eggs equivalent to 10.6 kg/ha/yr. Hatchlings may emerge from nests in the fall or may overwinter underground and delay emergence until the following spring. Sex determination of hatchlings is temperature-dependent, with a pivotal temperature at constant incubation temperatures of ca 28.4°C. Although this population occurs in a state park, the concentration of nesting activity principally along a linear corridor of artificial habitat has fostered nest predation approaching 100 percent; chief egg predators are raccoons (Procyon lotor) and fish crews (Corvus ossifragus). Some nesting females are also depredated, principally by raccoons. Continuing forest growth threatens to shade out the main nesting site and to skew the sex ratios of hatchlings toward males. We present management recommendations both for this population and for the species throughout Florida.

Shell disease in river cooters (Pseudemys concinna) and yellow-bellied turtles (Trachemys scripta) in a Georgia (USA) lake.

A disfiguring shell disease was detected in river cooters (Pseudemys concinna) and yellow-bellied turtles (Trachemys scripta) from Lake Blackshear, Georgia (USA). The turtles used were part of a mark-recapture study conducted from September 1991 to June 1993. Histologic changes on four turtles included acute segmental necrosis of the epidermis, followed by ulceration, necrosis of the underlying dermis and dermal bone, and exaggerated remodeling of bone. Additional findings included visceral inflammatory lesions and bacterial infection, sepsis and marked trematode ova granulomatosis. The cause of the shell lesions was not determined.

Prevalence and histopathology of shell disease in turtles from Lake Blackshear, Georgia.

Turtles in Lake Blackshear, Crisp County, Georgia (USA) were evaluated for shell disease during intensive trapping efforts on 8 and 9 May 1990. The disease was most prevalent in Pseudemys concinna (74%) and Trachemys scripta (35%). The degree of necrosis on the carapace was significantly positively correlated with the degree of necrosis on the plastron in T. scripta (rs = 0.50), but not in P. concinna (rs = 0.06). Female T. scripta with lesions were significantly larger than females without lesions. Lesions were not detected on six other species of turtles. Some areas contained multinucleate osteoclasts that were destroying bone. No tumors were detected in soft tissue samples.

Ecology of the Turtle Pseudemys concinna in the New River, West Virginia

Ecology of the Turtle Pseudemys concinna in the New River, West Virginia

Courtship of the Turtle, Pseudemys nelsoni

With the exception of Jackson and Davis' studies of the courtship of Trachemys scripta elegans (1972a) and Pseudemys concinna suwanniensis (1972b), our knowledge of the courtship patterns of these genera is based on fragmentary and anecdotal accounts (e.g., Davis and Jackson, 1973; Lardie, 1973; Jackson, 1977). Here we describe the courtship behavior of male Pseudemys nelsoni. Our results are based on the courtship behavior of two small adult males kept in the laboratory and 16 observations of courtship in the field at Rock Springs run, Apopka, Florida (Kramer, 1986). Most laboratory observations were made by UF on a male (plastron length = 18 cm) housed in a 100 x 40 x 40 cm aquarium. Water temperature varied from 22 to 30?C in the summer and from 20 to 26?C in the winter. An arti-

Food Partitioning in Three Sympatric Species of Map Turtle, Genus Graptemys (Testudinata, Emydidae)

Three species of map turtle, Graptemys geographica, G. ouachitensis and G. pseudo geo graphic a, inhabit the Mississippi River near Stoddard, Vernon Co., Wiscon- sin. Adult females of all three species are of similar size and are distinctly larger than males. One species, G. geographica, has a notably wider head than the other two. Quan- titative analysis of fresh stomach contents of 113 adult females, qualitative analysis of 74 others and feeding observations confirm that the three species use different foods and feeding strategies. Graptemys geographica is a carnivore specializing on mollusks. Grap- temys ouachitensis is an omnivore, but specializes in surface feeding. Graptemys pseudo- geographica is a general omnivore, overlapping the other two species both in food and feeding areas. Graptemys geographica seems to be limited by food availability. Graptemys ouachitensis represents 66% of the Graptemys in the study area and may be best at exploiting an apparently unlimited food resource of aquatic vegetation and insect larvae. In Arkansas, G pseudo geo graphica is a mollusk specialist, possibly due to lack of com- petition from G geographica and competition from the ubiquitous generalist, Pseudemys scripta, and the strict vegetarian, Pseudemys concinna.

Distribution and Habitats of Turtles in New Mexico

Distributional and habitat data on nine species of New Mexico turtles are presented by locality maps and text. The state's turtle fauna consists of Chelydra serpentina, Kinosternon flavescens, K. sonoriense, Terrapene ornata, Chry- semys picta, Pseudemys concinna, P. scripta elegans, P. scripta gaigae, Trionyx muticus, T. spiniferus emoryi, and T. spiniferus hartwegi. Active study of New Mexico turtles began in 1961 and since that time approximately 700 specimens have been added to the University of New Mexico collections. Specimens from other collections and published accounts were included in the locality maps for each species. The aquatic turtles are primarily distributed along the state's princi- pal river systems but individual species show marked differences in their ability to survive away from permanent waters. The single terrestrial species, Terrapene ornata, is widely distributed in the state below about 6,600 feet. Dense populations of Terrapene occur in the grasslands of northeastern New Mexico as well as in relatively dry, sandy desert areas in the southeast but were not found on steep, rocky, mountain slopes, in dense woodlands, or in seemingly suitable habitats in northwestern New Mexico. Much of the herpetological collecting in the southwest prior to 1900 was done in conjunction with United States governmental surveying expeditions or military activities. These explorations had accompany- ing naturalists, who amassed sizeable collections, and their names were often used in the description of the animals they collected. Turtles, because of difficulty in collecting without specialized equip- ment, were absent or poorly represented in these early collections. Van Denburgh (1924), providing the first major contribution to the knowledge of the state herpetofauna, listed five species of turtles. The

The relationship between age, blood serum cholesterol level and aortic calcification in the turtle

1. 1. Determination by spectrophotometric methods of blood serum cholesterol level and aortic calcium in an age series of the Suwannee terrapin, Pseudemys concinna suwanniensis, yielded total cholesterol values ranging from 210 to 300 mg/100 ml serum, and calcium values ranging from 27 to 62 mg/100 g dry wt. aorta. 2. 2. There appears to be a definite increase in blood serum cholesterol level with increase in age (size), whereas there is no apparent correlation between the relative amount of aortic calcium and the size of the animal.

The subunit dissociation properties of turtle hemoglobins

1. 1.|The apparent molecular weight of unpolymerized turtle hemoglobins as measured by gel filtration decreases with a decrease in protein concentration. Weights vary from 33 000 to 55 000 within the protein concentration range 0.002–1.2%. 2. 2.|The oxygen affinity of hemoglobin from the turtle, Pseudemys concinna texana, increases slightly when the protein concentration decreases below 0.1% at pH 6.50, but not at pH 8.00. The value of the interaction constant, n, appears to be independent of protein concentration within the range 0.003%–1.0%. 3. 3.|The molecular weight of polymerized hemoglobin appears to depend upon protein concentration only at pH 4.70 where the polymer dissociates upon sufficient dilution. This dissociation probably involves separation of the polypeptide chain subunits of each tetramer but not cleavage of a disulfide linkage. 4. 4.|Polymerization of those turtle hemoglobins capable of aggregation is favored by high pH and conditions promoting methemoglobin formation. At least 80% of the hemoglobin can polymerize to octameric or larger molecules. 5. 5.|Methemoglobin appears to be slightly more dissociated than carboxyhemoglobin under almost all conditions studied.

Variations in Heart Rate during Voluntary Diving in the Turtle Pseudemys concinna

Variations in Heart Rate during Voluntary Diving in the Turtle Pseudemys concinna

Some Aspects of the Hematology of Turtles as Related to Their Activity

The physiological characteristics of animals are correlated with the animal's activity as well as with their evolutionary history. Since blood is one of the best tissues for studying this correlation, an investigation was made on certain aspects of the blood chemistry of turtles. This investigation included the measuring and counting of the erythrocytes, the determination of the hemoglobin content and pH, the calculation of the specific gravity of the blood, and the accumulation of data for the oxygen and carbon dioxide dlssociation curves. Turtles were chosen as. experimental animals for the following reasons: their morphology and taxonomy have been adequately explored; differentiation between sexes is relatively simple; their habitats vary from terrestrial to aquatic; they are readily available; and finally they are easily kept under laboratory conditions. A number of important studies have contributed infornation to our knowledge of turtle hematology. These' include investigations by Southworth and RedfieId (1926), Redfield (1933), Tipton (1933), and Wintrobe (1933). Of these, the one most pertinent to the present study was that by Southworth and Redfield (1926) concerning the oxygen dissociation curve of Pseudemys concinna. Much of the data from the above cited papers and various other sources is summarized by Albritton (1952). While these various studies have contributed much to the understanding of turtle hematology, little has been done toward comparing the physiological characteristics of various species as a possible basis for understanding their activities. It is the purpose of the present study to compare the hematology of four different species and if possible to correlate the data so obtained with the activity of the turtles.

THE TRANSPORT OF GAS BY THE BLOOD OF THE TURTLE

The chief characteristics of the blood of the turtle Pseudemys concinna, considered as a system for the transport of oxygen and carbon dioxide, are its low corpuscular content (10 to 22 per cent by volume) and its high concentration of base bound as bicarbonate. These characteristics account fully for the shape and position of the carbon dioxide dissociation curve, the effect of oxygenation and reduction of the hemoglobin upon the carbon dioxide-combining power of the blood, and the distribution of carbon dioxide between the corpuscles and plasma. The oxygen-combining capacity of the turtle corpuscles does not differ from that of an equal volume of human erythrocytes. The oxygen dissociation curve is similar to that of mammalian blood and is affected in like manner by the quantity of carbon dioxide present. Its exact shape and position depend in part upon the number of corpuscles in the blood; in part its characteristics cannot be attributed to known chemical factors.