MODERN CRAYFISH BURROWS AS INDICATORS OF A SPRING AND PERCHED WATER TABLE, KANSAS ECOLOGICAL RESEARCH STATION, LAWRENCE, KANSAS

The primary objective of this part of a neoichnological pilot project was to characterize the distribution, depth, and morphology of crayfish burrows in relation to the hydrogeology of the Mud Creek floodplain. The alluvial deposystem occurs in a moist subhumid climate with 75 to 100 cm of rainfall. The burrows were constructed by the crayfish belonging to the complex of Cambarus diogenes diogenes. Transects were taken from the alluvial settings of Mud Creek across several different soil types from proximal (stream channel margin) to distal (floodplain to terrace) environments at the Robinson Tract of the University of Kansas Field Station and Ecological Reserve (KSR). Pits and trenches were excavated to describe and catalogue the types and distribution of crayfish burrows and their association with the immediate soil structures, moisture and water-table level, and parent material. Grain-size and organic content data for each of the pits were also collected.

We found that burrows occurred specifically in relation to a natural spring in the northeast section of Robinson Tract, away from any open and permanent water bodies. Several types of the crayfish burrows were cast with polyurethane resin and dental plaster across various positions adjacent to and away from the spring system. Crayfish burrows had complex architecture and shallow depths (30 to 50 cm) directly adjacent to the spring. Crayfish burrows had varied architectural complexity and intermediate depths of 50 to 100 cm about 5 to10 m away from the spring. Crayfish burrows were primarily vertical and slightly sinuous and ranged from 200 to 400 m in depth approximately 20 to 30 m away from the spring.

Field data show that crayfish burrow morphology changes with respect to the position of a perched water table produced by the outflow of the natural spring. The regional water table in this area ranges between 6 and 9 m below the surface and flows toward the Kansas River. Based on these findings, the KSR crayfish are terrestrial in habit when the perched water table dissipates during the greatest amount of evapotranspiration, similar to some types of Australian crayfish that burrow down to the depth of a perched water table and live in its environment after the perched water-table is depleted.

Funding was provided by NSFEPSCoR-KAN-29505.