Flattened musk turtle

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Flattened musk turtle
Sternotherus depressus.jpg
adult and hatchling
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Suborder: Cryptodira
Family: Kinosternidae
Genus: Sternotherus
Species:
S. depressus
Binomial name
Sternotherus depressus
Tinkle & Webb, 1955
Flattened Musk Turtle Range Map.png
The purple area on the map indicates where the flattened musk turtle is present
Synonyms [4]
  • Sternotherus depressus
    Tinkle & Webb, 1955
  • Sternothaerus depressus
    — Tinkle, 1958
  • Sternotherus minor depressus
    Wermuth & Mertens, 1961
  • Kinosternon depressum
    Iverson, Ernst, Gotte & Lovich, 1989
  • Kinosternon depressus
    — Welch, 1994

The flattened musk turtle (Sternotherus depressus) is a critically endangered species of freshwater turtle in the family Kinosternidae. The species is endemic to north-central and west-central Alabama. [5] [6]

Geographic range

S. depressus is an endemic with a restricted range, historically inhabiting the Black Warrior River drainage of north central Alabama. [7] Serious declines have been observed throughout its range, and it has likely been extirpated from greater than 70% of its historic range, especially in much of the Mulberry Fork and the Locust Fork of the upper Black Warrior River Basin. Sipsey Fork populations have fared significantly better due to protection offered by the Bankhead National Forest.

Description

A little turtle, S. depressus can have a straight carapace length of 7.5–10 cm (3.0–3.9 in) as an adult, with a record length of 11.4 cm (4+12 in). Both the common name and specific name refer to the fact that the species' carapace (upper shell) is much lower and flatter than those of the other members of the genus Sternotherus. In fact the flattened musk turtle looks as if someone had accidentally stepped on it, hence the common name. [7]

Diet

S. depressus are omnivorous and mostly rely on gastropods (snails) and pelecypods (mussels) as a large part of their diet. Crayfish, insects, and seeds are also consumed by S. depressus, but are not a main food item. A greater portion of snails were detected in the feces of denser populations of S. depressus. [8]

Behavior and Movement

S. depressus have an average home range of 332 meters, although home ranges as large as a kilometer were recorded. In areas of poorer habitat, it is possible that S. depressus may have to move more to fulfill its dietary needs. Light and moderate precipitation was correlated with more overall movement for S. depressus, but not overall activity (i.e. amount of time active during the day). The breeding and nesting season showed more overall activity and movement compared to the brumation season for S. depressus. [9]

Basking has been observed in S. depressus on rocks, trees, and logs, although it is thought to be related to disease or overall poor health. [10]

Captivity

Individuals of S. depressus have survived for more than 20 years in captivity.[ citation needed ] Although reproductive rates are low for the species, S. depressus has been bred infrequently in captivity with relative success. Future propagation efforts may be key to preserving and reintroducing the species once its habitat has been restored.

Threats and causes of decline

Erosion and siltation from extensive strip mining for coal and damming have been the leading causes of decline in the flattened musk turtle, with clear cutting, development, and pollution also playing significant roles in habitat degradation throughout its historic range. As historically rock and bedrock bottom creeks have turned to mud and sand bottom creeks due to erosion, S. depressus has lost the rock crevices it relies on to escape predation and the high stream flow rates that characterize the streams it inhabits.

Habitat fragmentation also poses a significant threat to S. depressus. Isolated populations have the potential to lose genetic viability and threaten normal population structure. Smaller isolated populations also have less resilience to human caused disturbance, and thus are more vulnerable. [11]

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References

  1. van Dijk PP (2016) [errata version of 2011 assessment]. "Sternotherus depressus ". IUCN Red List of Threatened Species . 2011: e.T20824A97383753. doi: 10.2305/IUCN.UK.2011-1.RLTS.T20824A9231032.en . Retrieved 27 October 2022.
  2. "Flattened musk turtle (Sternotherus depressus)". Environmental Conservation Online System. U.S. Fish & Wildlife Service. Retrieved 29 February 2024.
  3. 52 FR 22418
  4. Fritz, Uwe; Havaš, Peter (2007). "Checklist of Chelonians of the World". Vertebrate Zoology. 57 (2): 262. doi: 10.3897/vz.57.e30895 . ISSN   1864-5755.
  5. "Flattened Musk Turtle". Outdoor Alabama. Retrieved 2024-03-31.
  6. Dodd, C.K., Jr. 2008. Sternotherus depressus Tinkle and Webb 1955 – flattened musk turtle. In: Rhodin, A.G.J., Pritchard, P.C.H., van Dijk, P.P., Saumure, R.A., Buhlmann, K.A., and Iverson, J.B. (Eds.). Conservation Biology of Freshwater Turtles and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group. Chelonian Research Monographs No. 5, pp. 013.1-013.7, doi:10.3854/crm.5.013.depressus.v1.2008, //iucn-tftsg.org/cbftt/.
  7. 1 2 Conant, Roger (1975). A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition. Houghton Mifflin. Boston. xviii + 429 pp. + Plates1-48. ISBN   0-395-19979-4 (hardcover), ISBN   0-395-19977-8 (paperback). (Sternotherus depressus, pp. 42–43 + Plate 4 + Map 9).
  8. Marion, Ken R.; Cox, William A.; Ernst, Carl H. (1991). "Prey of the Flattened Musk Turtle, Sternotherus depressus". Journal of Herpetology. 25 (3): 385–387. doi:10.2307/1564608. ISSN   0022-1511.
  9. Jenkins, A. Joseph; Godwin, James C.; Warner, Daniel A.; Steen, David A. (2022). "Movement Ecology of Flattened Musk Turtles (Sternotherus depressus)". Journal of Herpetology. 56 (1): 1–7 via BioOne.
  10. Dodd, C. Kenneth (1988). "Disease and Population Declines in the Flattened Musk Turtle Sternotherus depressus". The American Midland Naturalist. 119 (2): 394–401. doi:10.2307/2425822. ISSN   0003-0031.
  11. Kenneth Dodd, C. (1990). "Effects of habitat fragmentation on a stream-dwelling species, the flattened musk turtle Sternotherus depressus". Biological Conservation. 54 (1): 33–45. doi:10.1016/0006-3207(90)90040-v. ISSN   0006-3207.

Further reading