26 Sep 2022

Occurrence of Silver, Bighead, and Black Carp in Waters Managed by the US Army Corps of Engineers

Abstract: This technical report (TR) documents the distribution of Invasive Carp - Silver Carp (Hypophthalmichthys molitrix), Bighead Carp (Hypophthalmichthys nobilis), and Black Carp (Mylopharyngodon piceus) in US Army Corps of Engineers (USACE) managed waters. Invasive carp were introduced into the US nearly half a century ago. As they spread across the US, they compete with and consume native species and Silver Carp jumping behavior reduces recreational use. The USACE is responsible for management of waterbodies at more than 440 projects. Information on these projects including the presence of Invasive Carp is reported in the USACE Operations and Maintenance Business Information Link (OMBIL) database. To supplement the Invasive Carp information from OMBIL, 47 online ichthyology collection and observation databases were searched; 18 had information on Invasive Carp locations. Combining the collection, observation and OMBIL reporting information, 82 USACE projects in 19 districts in 6 of 8 divisions have Silver/Bighead Carp and 19 projects in 9 districts and 3 divisions have Black Carp. Understanding the distribution of Invasive Carp is important to enable managers to be pro-active: planning control efforts, posting informational signs, instituting live bait restrictions, and thus reducing the chances of species introduction or limiting species impact.

24 Aug 2021

Geographic and Genetic Variation in Susceptibility of Butomus umbellatus to Foliar Fungal Pathogens

Abstract: Large-scale patterns of plant invasions may reflect regional heterogeneity in biotic and abiotic factors and genetic variation within and between invading populations. Having information on how effects of biotic resistance vary spatially can be especially important when implementing biological control because introduced agents may have different Impacts through interactions with host-plant genotype, local environment, or other novel enemies. We conducted a series of field surveys and laboratory studies to determine whether there was evidence of biotic resistance, as foliar fungal pathogens, in two introduced genotypes (triploid G1, diploid G4) of the Eurasian wetland weed, Butomus umbellatus L. in the USA. We tested whether genotypes differed in disease attack and whether spatial patterns in disease incidence were related to geographic location or climate for either genotype. After accounting for location (latitude, climate), G1 plants had lower disease incidence than G4 plants in the field (38% vs. 70%) but similar pathogen richness. In contrast, bioassays revealed G1 plants consistently received a higher damage score and had larger leaf lesions regardless of pathogen. These results demonstrate that two widespread B. umbellatus genotypes exhibit different susceptibility to pathogens and effectiveness of pathogen biological controls may depend on local conditions.