Soil hydric characteristics and environmental ice nuclei influence supercooling capacity of hatchling painted turtles Chrysemys picta.

1998 ◽  
Vol 201 (22) ◽  
pp. 3105-3112 ◽  
Author(s):  
J P Costanzo ◽  
J D Litzgus ◽  
J B Iverson ◽  
R E Lee

Hatchling painted turtles (Chrysemys picta) hibernate in their shallow natal nests where temperatures occasionally fall below -10 C during cold winters. Because the thermal limit of freeze tolerance in this species is approximately -4 C, hatchlings rely on supercooling to survive exposure to extreme cold. We investigated the influence of environmental ice nuclei on susceptibility to inoculative freezing in hatchling C. picta indigenous to the Sandhills of west-central Nebraska. In the absence of external ice nuclei, hatchlings cooled to -14.6 1.9 C (mean s.e.m.; N=5) before spontaneously freezing. Supercooling capacity varied markedly among turtles cooled in physical contact with sandy soil collected from nesting locales or samples of the native soil to which water-binding agents (clay or peat) had been added, despite the fact that all substrata contained the same amount of moisture (7.5 % moisture, w/w). The temperature of crystallization (Tc) of turtles exposed to frozen native soil was -1.6 0.4 C (N=5), whereas turtles exposed to frozen soil/clay and soil/peat mixtures supercooled extensively (mean Tc values approximately -13 C). Hatchlings cooled in contact with drier (less than or equal to 4 % moisture) native soil also supercooled extensively. Thus, inoculative freezing is promoted by exposure to sandy soils containing abundant moisture and little clay or organic matter. Soil collected at turtle nesting locales in mid and late winter contained variable amounts of moisture (4-15 % w/w) and organic matter (1-3 % w/w). In addition to ice, the soil at turtle nesting locales may harbor inorganic and organic ice nuclei that may also seed the freezing of hatchlings. Bulk samples of native soil, which were autoclaved to destroy any organic nuclei, nucleated aqueous solutions at approximately -7 C (Tc range -6.1 to -8.2 C). Non-autoclaved samples contained water-extractable, presumably organic, ice nuclei (Tc range -4.4 to -5.3 C). Ice nuclei of both classes varied in potency among turtle nesting locales. Interaction with ice nuclei in the winter microenvironment determines whether hatchling C. picta remain supercooled or freeze and may ultimately account for differential mortality in nests at a given locale and for variation in winter survival rates among populations.

2004 ◽  
Vol 82 (4) ◽  
pp. 594-600 ◽  
Author(s):  
Stephen A Dinkelacker ◽  
Jon P Costanzo ◽  
John B Iverson ◽  
Richard E Lee, Jr.

The overwintering habits of hatchling Blanding's turtles, Emydoidea blandingii (Holbrook, 1838), are not well understood. To ascertain whether these turtles are well suited to hibernation on land, we examined susceptibility to dehydration, supercooling capacity, resistance to inoculative freezing, capacity for freeze tolerance, and physiological responses to somatic freezing in laboratory-reared, hatchling E. blandingii. Rates of evaporative water loss (mean ± SE = 4.1 ± 0.2 mg·g–1·d–1) were intermediate to rates previously reported for the hatchlings of species known to hibernate on land and in water. Supercooled hatchlings recovered from a 1-h exposure to –8 °C or a 7-d exposure to –4 °C. Additional turtles supercooled to –14.3 ± 1.2 °C (mean ± SE) before spontaneously freezing. However, when immersed in frozen soil, their capacity to supercool was severely limited by an inability to resist inoculative freezing following contact with external ice and ice nuclei. Therefore, hatchlings likely do not use supercooling as a winter survival strategy. Hatchlings tolerated a 72-h period of somatic freezing to –3.5 °C and responded to somatic freezing by increasing plasma concentrations of the putative cryoprotectants lactate and glucose. Our results suggest that hatchling E. blandingii could overwinter in moist, terrestrial hibernacula where risk of dehydration is reduced and freeze tolerance is promoted.


Ecology ◽  
2000 ◽  
Vol 81 (2) ◽  
pp. 346-360 ◽  
Author(s):  
Jon P. Costanzo ◽  
Jacqueline D. Litzgus ◽  
John B. Iverson ◽  
Richard E. Lee

Ecology ◽  
2000 ◽  
Vol 81 (2) ◽  
pp. 346 ◽  
Author(s):  
Jon P. Costanzo ◽  
Jacqueline D. Litzgus ◽  
John B. Iverson ◽  
Richard E. Lee

2000 ◽  
Vol 203 (22) ◽  
pp. 3459-3470 ◽  
Author(s):  
J.P. Costanzo ◽  
J.D. Litzgus ◽  
J.B. Iverson ◽  
R.E. Lee

Hatchling painted turtles (Chrysemys picta) commonly hibernate in shallow, natal nests where winter temperatures may fall below −10 degrees C. Although hatchlings are moderately freeze-tolerant, they apparently rely on supercooling to survive exposure to severe cold. We investigated seasonal changes in physiology and in the development of supercooling capacity and resistance to inoculative freezing in hatchling Chrysemys picta exposed in the laboratory to temperatures that decreased from 22 to 4 degrees C over a 5.5 month period. For comparison, we also studied hatchling snapping turtles (Chelydra serpentina), a less cold-hardy species that usually overwinters under water. Although Chrysemys picta and Chelydra serpentina differed in some physiological responses, both species lost dry mass, catabolized lipid and tended to gain body water during the acclimation regimen. Recently hatched, 22 degrees C-acclimated Chrysemys picta supercooled only modestly (mean temperature of crystallization −6.3+/−0.2 degrees C; N=6) and were susceptible to inoculation by ice nuclei in a frozen substratum (mean temperature of crystallization −1.1+/−0.1 degrees C; N=6) (means +/− s.e.m.). In contrast, cold-acclimated turtles exhibited pronounced capacities for supercooling and resistance to inoculative freezing. The development of cold hardiness reflected the elimination or deactivation of potent endogenous ice nuclei and an elevation of blood osmolality that was due primarily to the retention of urea, but was not associated with accumulation of the polyols, sugars or amino acids commonly found in the cryoprotection systems of other animals. Also, Chrysemys picta (and Chelydra serpentina) lacked both antifreeze proteins and ice-nucleating proteins, which are used by some animals to promote supercooling and to initiate freezing at the high temperatures conducive to freezing survival, respectively.


1985 ◽  
Vol 63 (1) ◽  
pp. 67-70 ◽  
Author(s):  
William H. N. Gutzke ◽  
Gary C. Packard

Most hypotheses addressing the significance of intraspecific variation in size of reptilian eggs have focused on potential benefits accruing to the large hatchlings that usually emerge from large eggs. We find, however, that large eggs of painted turtles (Chrysemys picta) have a significantly higher probability of hatching than do small eggs incubated under many conditions of temperature and moisture. Surface area to volume considerations may account for differences in hatching success between large and small eggs incubated in dry conditions. Natural selection for size of reptilian eggs may therefore be more intense than has been suspected heretofore, because differential mortality related to egg size probably occurs in prenatal as well as early postnatal stages in the life cycle.


Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 665
Author(s):  
Ladislav Holik ◽  
Jiří Volánek ◽  
Valerie Vranová

Soil proteases are involved in organic matter transformation processes and, thus, influence ecosystem nutrient turnovers. Phytohormones, similarly to proteases, are synthesized and secreted into soil by fungi and microorganisms, and regulate plant rhizosphere activity. The aim of this study was to determine the effect of auxins, cytokinins, ethephon, and chlorocholine chloride on spruce forest floor protease activity. It was concluded that the presence of auxins stimulated native proteolytic activity, specifically synthetic auxin 2-naphthoxyacetic acid (16% increase at added quantity of 5 μg) and naturally occurring indole-3-acetic acid (18%, 5 μg). On the contrary, cytokinins, ethephon and chlorocholine chloride inhibited native soil protease activity, where ethephon (36% decrease at 50 μg) and chlorocholine chloride (34%, 100 μg) showed the highest inhibitory effects. It was concluded that negative phytohormonal effects on native proteolytic activity may slow down organic matter decomposition rates and hence complicate plant nutrition. The study enhances the understanding of rhizosphere exudate effects on soil microbial activity and soil nitrogen cycle.


1993 ◽  
Vol 130 (2) ◽  
pp. 314 ◽  
Author(s):  
Nat B. Frazer ◽  
Judith L. Greene ◽  
J. Whitfield Gibbons

1979 ◽  
Vol 57 (5) ◽  
pp. 1046-1051 ◽  
Author(s):  
Shannon F. Timmers ◽  
Paul D. Lewis Jr.

One new monogenean is described and 11 other helminths are reported from painted turtles from eastern Manitoba. Polystomoides pauli sp.n. from the host's oral mucosa most closely resembles P. coronatum (Leidy) and P. oris Paul. It differs from the former in having more and larger genital coronet spines, and possession of anterior cecal diverticula, and from the latter in size, larger number of genital coronet spines, and possession of great hooks with entire, not bifid, roots. Price's emendation of P. coronatum to include five species he held to be its synonyms is rejected; and the five species, P. opacum Stunkard, P. megacotyle Stunkard, P. microcotyle Stunkard, P. albicollis MacCallum, and P. digitatum MacCallum are designated species inquirendae. Polystomoides coronatum is restricted to the redescription given for it by Stunkard. The trematodes Crepidostomum sp., Eustomos chelydrae, Microphallus opacus, Protenes angustus, Spirorchis parvus, S. scripta, Telorchis attenuatus, and T. corti, the cestode Proteocephalus sp., and the nematodes Serpinema trispinosa and Spiroxys contortus are reported from Chrysemys picta belli. Except for P. angustus, all represent first reports from turtles in Canada. This is the first report of E. chelydrae from the host stomach, and the second report of M. opacus from naturally infected turtles.


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