Prairie designers: Cambarus diogenes as an ecosystem engineer in a coastal tall grass prairie
Emily Katherine Brady, Shania E Hurst, Ryan William Reihart
In a coastal tallgrass prairie, fatclaw crayfish (Cambarus diogenes) are an abundant, but little studied species. They burrow from the water table to the surface, carving chambers where groups of crayfish live, and assembling a soil “chimney” that they use to access the prairie. It is unknown how these crayfish that move vast amounts of soil may be affecting prairie ecosystem processes, or if soil nutrients affect where chimneys are found. Little is also known about the diet of the fat claw crayfish or their trophic placement in a prairie food web. We determined how nutrients affect the abundance of chimneys by counting the number of chimneys in a large fertilization experiment that manipulated (N&P, Ca, K, and Na). Conversely, we also determined if crayfish affect soil characteristics by measuring total soil moisture and bulk density, total nutrient concentrations, and nutrient availability from chimneys and soils at an increasing distance away from chimneys. Using our estimates of chimney abundances, we also determined how much soil crayfish move, and how they affected soil nutrient pools and availability. Additionally, we collected crayfish claws and used stable isotopes to determine the placement of this species in the prairie food web. The abundance of crayfish was affected by soil nutrients. Plots containing a combination of N&P and Ca tended to have a higher abundance. Conversely, crayfish chimneys also affected soil characteristics: the soils from chimneys were very high in available sulfur compared to soils away from chimneys. A total of 245.76 g/m 2 of clayey soil was likely brought up from anaerobic conditions where sulfur-reducing bacteria are present. Available potassium was lower at the base of the chimney, and got progressively higher the further you moved from the chimney. Because Cambarus diogenes significantly affected available soil nutrients, they likely play an important role in structuring plant communities and nutrient cycling in these rare prairies. As ecosystem engineers, their presence may be important in coastal prairie restoration and conservation. The cycling of nutrients cause by the crayfish building chimneys could manipulating what plants are able to grow in the ecosystem, and some plants need specific nutrients to be successful. Crayfish could be the key to helping preserve the fading prairie ecosystem.
Kathleen A. Kargl, Chelse M. Prather
Primary Advisor's Department
Stander Symposium project
"Prairie designers: Cambarus diogenes as an ecosystem engineer in a coastal tall grass prairie" (2018). Stander Symposium Projects. 1417.