Study

The role of controlled propagation on an endangered species: demographic effects of habitat heterogeneity among captive and native populations of the Socorro isopod (Crustacea: Flabellifera)

  • Published source details Lang B.K., Douglas A. Kelt D.A. & Shuster S.M. (2006) The role of controlled propagation on an endangered species: demographic effects of habitat heterogeneity among captive and native populations of the Socorro isopod (Crustacea: Flabellifera). Biodiversity and Conservation, 15, 3909-3935.

Summary

The endangered Socorro isopod Thermosphaeroma thermophilum is endemic to an isolated freshwater warm spring in New Mexico, southwest USA. Habitat loss and degradation resulted in extirpation of the wild population near Socorro, NM. This event prompted controlled propagation to initiate recovery of the species. Age-specific microhabitat segregation of this isopod was examined in artificial and native habitats, short- and long-term demographic patterns of captive populations in response to induced habitat manipulations, and overall experimental results of propagation as an effective method for management of this endangered species.

Propagation facility: The Socorro Isopod Propagation Facility was established in 1990. The facility consists of two separate systems of four small artificial pools (0.53 m wide x 1.63 m long x 0.75 m high) connected by pipes that are supplied with water from the native spring.

Habitat treatments and population responses: Captive populations (eight) were exposed to four artificial habitat treatments: control (no treatment); rocks only; plants only; rocks and plants. These were repeated over two 50-month experimental periods (Trial 1: July 1995 to August 1999; Trial 2: August 1999 to September 2003). Quantitative measures (benthic and sweep samples) of population density and age structure were compared among these managed subpopulations using the native population as a demographic baseline.

The native population remained significantly more abundant than captive subpopulations during the 100-month study. Population trends among artificial habitats differed slightly between the trials, but the captive populations responded to habitat quality, i.e. pools with plants supported higher densities than other treatments. Isopod age structure was most heterogeneous in pools with plants suggesting that vertical structural diversity is necessary to maintain long-term viability in captivity.

Observations of “breeding huddles” in all artificial habitats implied that propagation may affect the social basis of the species’ mating system, as this behaviour was not observed in wild populations.This could be a behavioural response to selection on body size that may reduce predation risks from larger cannibalistic males, or to increase fitness of both sexes under spatially altered sex ratios of artificial environments.

Conclusions: Habitat condition in controlled environments evidently plays a critical role, significantly affecting Socorro isopod body size and genetic affinities between captive and native population of this isopod.


Suggested reading: Shuster S.M., Miller M.P., Lang B.K., Zorich N., Huynh L. & Keim P. (2005) The effects of controlled propagation on an endangered species: genetic differentiation and divergence in body size among native and captive populations of the Socorro isopod (Crustacea: Flabellifera). Conservation Genetics, 6, 335-368.


Note: If using or referring to this published study please read and quote the original paper, this can be viewed at:

http://www.springerlink.com/content/fj1377658v2uh361/

Output references
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.


Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust