Burrowing crayfish prefer burning to boiling

Prescribed burn on the Mississippi Sandhill Crane Wildlife Refuge. Courtesy photo by U.S. Fish & Wildlife Service.

Crayfish burrow amongst the prairie roots
But are they affected by the woody shoots?
Turns out as the woody stems get tall
The number of crayfish burrow openings begins to fall.

We know many species benefit from fire, but burrowing crayfish? USDA Forest Service scientist Susan Adams led a study that found the number of active crayfish burrow openings was greater in areas managed with burning and mowing than unmanaged areas.

The Mississippi Sandhill Crane National Wildlife (MSCNW) Refuge, where the study took place, was established in 1975 to conserve the last remaining populations of its namesake: the Mississippi sandhill crane (Grus canadensis pulla).

Open, fire-maintained pine savannas and prairies cover about half the refuge. Their restoration has brought the Mississippi sandhill crane back from the brink of extinction and provided habitat for a host of other rare plant and animal species like pitcher plants.

Several years ago, Scott Hereford, the MSCNW Refuge manager, contacted Adams concerning a burrowing crayfish on their sensitive species list. “They were interested in understanding how their management was affecting the speckled burrowing crayfish (Creaserinus danielae),” says Adams. “I was excited to learn more about this understudied species and burrowing crayfish in general.”

Adams and Hereford designed the study to directly and indirectly sample crayfish. Chaz Hyseni, SRS ORISE fellow, contributed with statistical analyses. Their results were published in the journal Water.

First, the researchers counted the number of active burrow openings in quadrats along transects. They also took height measurements of woody and herbaceous stems and cover estimates for herbaceous and woody plants. They then directly sampled crayfish by digging them out of burrows, suctioning them out with a slurp gun, or trapping them.

A large crayfish chimney in front of pale pitcher plants (Sarracenia alata). USDA Forest Service photo by Susan Adams.

Unmanaged areas had more and taller woody vegetation and fewer crayfish burrow openings. “We are not sure why there were less crayfish burrows in areas with taller woody stems. It may have to do with temperature, food sources, predators, or disease. What is clear is that vegetation management is having a net positive affect on burrowing crayfish numbers in the area,” says Adams.

While the dominant species they found was not the speckled burrowing crayfish, it was in the same genus as the sensitive species (Creaserinus oryktes). “Crayfish taxonomy is still in flux,” says Adams, “but this study allowed us to better understand the habitat needs of a species closely related to the speckled burrowing crayfish.”

The fire-maintained, southeastern pine savannas and prairies are rare ecosystems and biodiversity hotspots. The Southeast is also a global biodiversity hotspot for crayfish. This high biodiversity results partly from the fact that these areas were never glaciated, and thus, evolution has been acting on the taxa for hundreds of thousands of years.

Additionally, the many highly productive river drainages support a wide diversity of aquatic life and have allowed the rapid evolution of many crayfish species, as their ranges tend to be small.

Because fire was such an important force shaping prairie ecosystems, it follows that the semi-aquatic burrowing crayfish living in these environments would be adapted to frequent fire. Understanding the relationship between the burrowers and fire is important for crayfish conservation and management.

Read the full article in Water.

For more information, email Susan Adams at susan.adams@usda.gov.

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