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University of Michigan Biological Station

The University of Michigan Biological Station (UMBS) was founded in 1909.

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Assessing the community impact of crayfish parasitization

Project Abstract: 
Crayfish alter feeding preferences when parasitized by the diagenetic trematode, Microphallus sp. Crayfish play a large role in aquatic ecosystems, being keystone species and ecosystem engineers. Specifically, crayfish significantly decrease submersed aquatic vegetation biomass through consumption, though crayfish also consume benthic macroinvertebrates, including insect larvae, snails, and zebra mussels. Mesocosms will be established with macrophytes and benthic macroinvertebrates. Crayfish with a range of Microphallus sp. parasite loads will be added to the mesocosms. The mass of the crayfish prey will be weighed to determine how biomass of these essential organisms is altered by crayfish predation and if the consumption is different for parasitized crayfish. This project is the second project of my dissertation and must be completed this summer in order for me to graduated on time (May 2022) with my PhD. Therefore, it is imperative that I am able to come to UMBS this summer to utilize the mesocosms and crayfish collection sites that have previously been established as infected or uninfected in my previous summer.
Investigators: 
pmoore
rthublin
Years Active: 
2020
Methods: 
Mesocosms (2 m wide and 1 m deep) will be divided into 4. One crayfish (Faxonius rusticus), 21 grams of macrophytes (Certaophyllum demersum, Chara sp., Elodea canadensis), 20 pond snails (Lymnaea and Campeloma), 100 benthic macroinvertebrates, and 20 zebra mussels (Dreissena polymorpha) will be placed into each section of the mesocosm. The crayfish will be collected from many sites that were utilized in 2019, ensuring that crayfish have a wide range of parasite loads. Crayfish within the same mesocosm will be from the same site, maximizing the likelihood that they have similar parasite loads. Trials will run for 4 weeks. Macrophytes, snails, and zebra mussels will be counted and measured weekly. At the end of the trials, benthic macroinvertebrates will be counted. Parasite load of crayfish will be determined at the end of each trial using photo processing techniques in Image J software. The processed photos will tell the percent of the hepatopancreas that is parasitized by Microphallus sp., which is defined as parasite load. The weight of the prey will be regressed against the parasite loads of the crayfish to determine if parasite load is affected prey weight. If they weight of the prey categories is affected differently with different parasite loads, this project would show that crayfish parasite load affects the relative abundances of many basal food web fauna. After 4 weeks, mesocosms will be drained and cleaned out. Trials will be repeated twice, for a total of 80 trials.