Browsing by Subject "invasive"

Now showing 1 - 3 of 3
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    Dietary Niche and Growth Rate of the Nonnative Tubenose Goby (Proterorhinus semilunaris)
    (2019-05) Dawson , Bradley
    Basic life history knowledge is essential to determine if a nonnative species is potentially invasive. The nonnative tubenose goby (Proterorhinus semilunaris) arrived in the Great Lakes in the 1990s via ship ballast water, but remains poorly studied within North America, making it difficult to predict its effects on native ecosystems. Diet and growth patterns were examined from age-0 tubenose gobies within the estuary of the St. Louis River, a tributary to Lake Superior near Duluth, Minnesota. Dietary breadth and growth rates have important ramifications for survival, competitiveness, and dispersal ability of a fish species, influencing its potential success as an invasive species. I sampled tubenose gobies from shallow vegetated habitat via beach seine during summer and fall periods, and removed otoliths and aged fish on daily increments for growth modelling. Furthermore, stomach contents were identified and weighed to provide measures of fitness and dietary breadth between seasons (fall vs. summer) and between several locations within the estuary. Results suggest a low dietary breadth that overlaps with tadpole madtom (Noturus gyrinus); tubenose goby diet was mostly comprised of Crustacea, regardless of location or season. Growth modelling demonstrates that tubenose gobies reach a small maximum size and are short-lived, indicating an r-selected life history. The Gompertz function is preferred for modelling the growth of this species.
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    Genetic Diversity, Structure, and Cold Hardiness of Invasive Knotweed (Fallopia spp.) in Minnesota
    (2022-04) Drazan, Dallas
    Knotweed (Fallopia spp.) is an herbaceous perennial from East Asia that was brought to Europe and North America and, despite control efforts, subsequently spread aggressively on both continents. Knotweed are known to cause structural damage, riverbank destabilization, and outcompete native species thus reducing biodiversity. Two experiments were conducted: a controlled freezing chamber study to quantify the rhizome cold hardiness of the knotweed complex and whole genome sequencing (DArTseq) of 1,249 individuals from North America, Europe, and Asia with a focus on Minnesotan populations used to measure genetic diversity, population structure, species composition, and indirectly measure asexual and sexual dispersal of knotweed. Fallopia japonica and F. sachalinensis were found to be cold hardy to -10°C and F. xbohemica to -9°C. Minnesota knotweed are genetically diverse and spread both sexually and asexually with the hybrid F. xbohemica being the most prevalent taxon in Minnesota.
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    KHV disease data from wild Cyprinus carpio from Lake Elysian (Le Seuer, MN) and cohabitation disease trial of Cyprinus carpio, Pimephales promelas and Carassius auratus
    (2020-09-28) Tolo, Isaiah; Phelps, Nicholas; phelp083@umn.edu; Phelps, Nicholas; Minnesota Aquatic Invasive Species Research Center
    Koi herpesvirus (KHV) is an important pathogen worldwide and a common cause of mass mortality events of wild common carp (Cyprinus carpio) in North America, however reference strains and genomes obtained from wild carp are not available. Additionally, it is unclear if fishes native to North America are susceptible to KHV infection due to incomplete susceptibility testing. Here we present the first North American type strain and whole genome sequence of KHV isolated from wild carp collected from a lake with history and recent incidence of carp mortality. Additionally, the strain was used in an in-vivo infection model to test the susceptibility of a common native minnow (Pimephales promelas) and goldfish (Carrasius auratus) which is invasive in North America. Detection of KHV DNA was confirmed in the tissues of a single fathead minnow but the same tissues were negative for KHV mRNA and samples from exposed fathead minnows were negative on cell culture. There was no detection of KHV DNA or mRNA in goldfish throughout the experiment. KHV DNA in carp tissues was reproducibly accompanied by detection of KHV mRNA and isolation on cell culture. Additionally, environmental KHV DNA was detected on all tank filters during the study. These findings suggest that fathead minnows and goldfish are not susceptible to KHV infection and that detection of KHV DNA alone in host susceptibility trials should be interpreted with caution