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Contributed Talk

Session: : Invasion: Species Interactions 2

COS 41-1 - Symbiotic interactions between native and invasive hosts change during long period exposure

Monday, August 7, 2023
3:30 PM – 3:45 PM PDT
Location: E141
Abstract: Symbiosis is a component of the life history of most multicellular organisms. Symbiosis can affect growth rates, alter host mortality, and even affect immune-suppressant properties. However, the relationship between hosts and their symbionts is not a given. Multiple factors can disrupt the interactions between hosts and symbionts. The potentially disruptive effects of invasive species on native host-symbiont relationships is an emerging global change threat because invasive species compete with natives for essential resources such as food and habitat. Invasive species may also affect endemic symbionts as another resource. In the Virginia Mountain Lake Region the increase of invasive crayfish species has led us to examine the prolonged effects of symbiotic relationship amongst invasive hosts and native symbionts. The primary objective was to encourage symbiotic relationships between invasive hosts and native branchiodbellidan symbionts, and observe the effects of a long term symbiotic relationship between them. The secondary objective was to observe how invasive and native hosts differed under long term exposure to native symbionts.


To complete the primary objective, we conducted an aquarium experiment in which two invasive hosts, Faxonius cristavarius and Faxonius virilis, were encouraged to interact with native symbionts by decreasing their ability to groom. Invasive crayfish have aggressive grooming behavior towards native branchiobdellidans, typically making them less suitable hosts than native species. We used 24 37.8 liter aquaria into which ½ of the individuals of each host species were subjected to dactyl ablation on the walking legs while the other ½ served as unmanipulated controls. We ran the experiment for three months, with measures of host growth as the primary response variables. The results of the primary objective showed F. virilis had similar growth rates between the experimental and control group. F. cristavarius had a significant difference between the experimental and control group. The control group for F. cristavarius had around little to no growth, while the experimental group had continuous growth over the duration of the study. To complete the secondary objective we used a 3-way factorial between two crayfish species, dactyl ablations, and the absence of branchiobdellidans as a treatment. The factorial used an invasive crayfish species, F.cristavarius, a native crayfish species Cambarus appalachiensis to observe how invasive and native hosts differ when exposed to native symbionts.The results of the experiment suggested that C. appalachiensis had higher growth rates than F.cristavarius. However, F. cristavarius only had significant growth after exposure to branchiobdellidans.