IMPACTS OF REMOVAL OF INVASIVE CRAYFISH PROCAMBARUS CLARKII ON MACROPHYTES AND MACROINVERTEBRATES IN AN URBAN, FLOWING SYSTEM

Procambarus clarkii (red swamp crayfish) is a species of great concern in the Laurentian Great Lakes area due to the recent discovery of established populations in inland and Great Lakes-connected waters. In other systems, introduction of P. clarkii has resulted in reduced abundance of macrophytes and macroinvertebrates and increased competition with native crayfish species. A high-density population is established in the North Shore Channel of the Chicago Area Waterway System (CAWS). The CAWS is a system of canals that connects Lake Michigan to the Mississippi River Basin. We have implemented intensive trapping and removal of P. clarkii to reduce population size in this system. Our goals in this work are to reduce population size so that the chance of spread is lessened and to reduce ecosystem effects. We have conducted intensive trapping of the population during six consecutive summers (2018-2023) using baited traps. We conducted macrophyte and macroinvertebrate sampling in the summer of 2023 to determine species density and richness in two reaches where we intensively trap and remove P. clarkii. Results from these reaches were compared to a control reach where crayfish are not removed. We found that both macrophyte species density (p << 0.01) and species richness (p << 0.01) were significantly greater in the control reach compared to the removal reaches. Macroinvertebrate species density and richness were not significantly different in the control reach compared to the removal reaches. Our study demonstrates that control efforts of invasive crayfish such as P. clarkii can reduce population size but that ecosystem outcomes can vary. 

Primary Presenter: Rachel Egly, Loyola University Chicago (regly@luc.edu)

Authors:

Rachel Egly, Loyola University Chicago  (regly@luc.edu)

Reuben Keller, Loyola University Chicago  (rkeller1@luc.edu)