Distribution and ongoing threat of invasive scud (Apocorophium lacustre) to the Illinois River and Laurentian Great Lakes

Apocorophium lacustre is a species of benthic amphipod native to both American and European estuaries along the North Atlantic Ocean, which has rapidly expanded outside of its native range and is now established in the Illinois, Upper Mississippi, and Ohio Rivers. A. lacustre has previously been detected in the Illinois River within 100 river km of Lake Michigan and is considered high risk for colonization and disruption of the Great Lakes’ benthic communities. In order to further our understanding of factors influencing A. lacustre distribution and the threat it poses to the Great Lakes, I deployed rock bag colonization samplers and collected zoobenthic and habitat data at 263 sites distributed across the eight navigational pools of the Illinois River. A. lacustre was identified in all pools up to and including the Dresden Island Pool - the species was not observed any closer to the Great Lakes than previously documented. A. lacustre were by far the most abundant benthic amphipod collected in pools where the species was present, representing >79% on average of benthic amphipods collected at sites downstream of the Dresden Island Lock & Dam (which represents the leading edge of its invasion). I analyzed abundance and habitat data using two generalized linear mixed effects model (GLMM) and AICc approaches: predicting A. lacustre abundance using a negative binomial GLMM and predicting the proportion of A. lacustre amongst all benthic amphipods using a binomial GLMM. I identified several variables that are useful predictors of A. lacustre’s raw and proportional abundance: dissolved organic matter had a strong negative effect and distance downstream within each river pool (e.g., closer to the next downstream dam) had a strong positive effect in both analyses. The latter result suggests that A. lacustre invasion is at least partially facilitated by impoundments on the Illinois River, which create areas of low water velocity, higher salinity, and disrupted biological communities. My results indicate that A. lacustre may struggle to find suitable habitat in the canals of the Upper Illinois River Waterway, but they may be successful in Lake Michigan if introduced.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Natural Res & Env Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Henry, Trent William

Contributors dc:contributor

• Lamer, James T
• Larson, Eric R
• Keller, Reuben P

• invasive species
• upper mississippi river basin
• illinois river
• chicago river
• aquatic invasive species
• apocorophium
• apocorophium lacustre
• amphipods
• estuarine amphipods

Statement dc:rights

• Copyright 2022 Trent Henry

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/116280

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F116280