Literaturdatenbank
Literaturdatenbank |
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Mitchell, J. C. (1988). Population ecology and life histories of the freshwater turtles chrysemys picta and sternotherus odoratus in an urban lake. Herpetol. Monogr., 2, 40–61.
Added by: Sarina Wunderlich (13 Oct 2008 21:32:52 UTC) Last edited by: Beate Pfau (01 Aug 2009 08:23:10 UTC) |
| Resource type: Journal Article BibTeX citation key: Mitchell1988a View all bibliographic details  |
Categories: General Keywords: Chrysemys, Chrysemys picta, Emydidae, Habitat = habitat, Kinosternidae, Nordamerika = North America, Schildkröten = turtles + tortoises, Sternotherus, Sternotherus odoratus Creators: Mitchell Collection: Herpetol. Monogr. |
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| Abstract |
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Chrysemys picta Sternotherus odoratus A multiple mark-recapture technique was used to study the population ecology and life histories of syntopic populations of Chrysemys picta and Sternotherus odoratus in an urban lake in central Virginia, U.S.A. Laurel Lake is a shallow, polymictic reservoir located in a former golf course. The most unbiased estimate of population size was provided by the Bailey triple-catch method; the C. picta population was estimated to contain 517 ± 17 individuals in 1980 and the S. odoratus population 534 ± 45 individuals. Chrysemys picta biomass (28.3 kg/ha) was more than twice that of S. odoratus biomass (13.6 kg/ha). Sex ratios for both species did not differ significantly from unity. Differences between estimates of recruitment (immigration and natality) and losses (emigration and deaths) indicated growing populations at rates of 7.2% for C. picta and 3.2% for S. odoratus. Males in both populations averaged younger than females. Annual survivorship was high for all age and sex groups in C. picta (94-96%), except for juveniles (46%). Survivorship in S. odoratus was 84-86% for all age and sex groups. These populations exhibited a Type II (ecological) survivorship curve. Mortality resulted from unnatural agents (vehicles, grass mowers, removal) and natural predators. Body sizes of C. picta and S. odoratus averaged less than those in other central Virginia populations. Comparisons of environments among lakes suggest that body size variation may be due to the presence or lack of submerged aquatic vegetation which in turn indicates high to low resource availability and quality. Reproductive cycles are generally synchronous with other central Virginia populations. Clutch size is not significantly correlated with body size in Laurel Lake C. picta but is in S. odoratus. Clutch size in C. picta from Laurel Lake (x̄=4.1) was nearly identical to that in a nearby population; S. odoratus exhibited a smaller clutch size (x̄=2.7). Some individuals of both species produce multiple clutches. Hatchling C. picta overwintered in the nest and emerged in March and April; hatchling S. odoratus emerged in the year of egg deposition. The life history of Chrysemys picta in Laurel Lake is best described by the bet-hedging model with high and unpredictable juvenile mortality and exhibits late maturity, small reproductive effort, and long life. The life history of S. odoratus fits the bet-hedging model with low and predictable juvenile mortality and exhibits earlier maturity, larger reproductive effort, and shorter life. Added by: Sarina Wunderlich Last edited by: Beate Pfau |