Transactions of the Illinois State Academy of Science [Volume 115 (2022)]
Round Goby (Neogobius melanostomus) Introduction and Range Expansion in the Highly Anthropogenic Influenced Watershed of the Des Plaines River, Illinois, USA
Author: Matthew A. Sarver
The Round Goby (Neogobius melanostomus) is an invasive species of fish introduced to the Great Lakes drainage in the early 1990s. The species has since expanded its range into the Mississippi River watershed through the Chicago Sanitary and Ship Canal. The Midwest Biodiversity Institute (MBI) has observed expansion in the highly anthropogenically influenced Des Plaines River and its tributaries beginning in 2014. Densities of Round Goby were compared to habitat conditions and select analytes to determine what factors are fueling colonization and proliferation in these new localities. The selected model indicates habitat conditions, nitrates, conductivity, total Kjeldahl nitrogen (TKN), total suspended solids (TSS), temperature, and dissolved oxygen (D.O.) are all significant. Poor quality habitat, high concentrations of TSS and TKN are not well tolerated, while high concentrations of nitrates, low D.O., high temperatures, and high specific conductance are tolerated by Round Goby.
Keywords: Invasive species, Round Goby, Water Quality
Strong Reductions in Bigheaded Carp Size at Age Accompany Increasing Population Densities
Authors: Daniel K. Gibson-Reinemer, Richard M. Pendleton, Levi E. Solomon, John H. Chick, and Andrew F. Casper
Since their arrival in the 1990s, invasive bighead carp (Hypophthalmichthys nobilis) and silver carp (Hypophthalmichthys molitrix) have attained exceptional population densities and growth rates in the Illinois River. Standardized monitoring encompassing the duration of the invasion provides a rare opportunity to examine changes in the size distribution of age-0 and adult (age-3+) cohorts as biomass expanded dramatically. Biomass of bigheaded carps sampled expanded 150-fold, from just over 3,000 kg in 2000 to over 490,000 kg in 2013. Over the period of invasion, size distributions within both age-0 and adult cohorts have consistently fallen as population densities increased, strongly implying constraints on individual growth rates. Between 2000 and 2014, the mode of total lengths of age-0 bigheaded carps fell by 67%, whereas the 50th and 75th percentiles of adult silver carp lengths declined by 25%. Declines in zooplankton abundance and native planktivore condition suggest density-dependent competition for food likely has driven the decline in the size at age for both age groups. The trends observed in this study may provide useful information on how size distributions can vary across densities, particularly during the exponential growth phase of invasions.
A Technique for Germinating Seeds of Invasive Japanese Hop (Humulus japonicus Cannabaceae) and Indication of Seed Dormancy Characteristics
Authors: Kurt Schulz and Jonathan Clark
Japanese hop (Humulus japonicus Sieb. & Zucc.), an invasive herbaceous vine from eastern Asia, is a threat to river bottom and moist soil communities throughout eastern North America. This disturbance fugitive is difficult to control due to rapid vegetative growth rates and copious supplies of highly dispersible achenes (“seeds”). Herbicide and cutting treatments have only temporary effects, indicating a new approach should be developed. A reliable means for growing research plants is therefore needed. We investigated a technique for germinating seeds collected from nature and subsequently stored under dry conditions. Hop seed was collected from four sites in southern Illinois, allowed to air dry one month and then subjected to dry after-ripening treatments of 2, 6, and 12 months at 4 °C. Seeds were subsequently sterilized and subjected to cold, moist stratification until germination was detected. Germination was ca. 50% after two months after-ripening but rose to ca. 80% at 6 and 12 months. Germination rates at two months seemed to vary between sites, but this was not statistically significant. Synthesizing this result with other literature, it appears that hop can germinate immediately if it is cold stratified for 30 days but requires more than two months after-ripening and cold stratification if it is allowed to dry. Given high germination rates and lack of contamination seen here, we recommend our sterilization protocol. Possible variations in seed maturity between collection sites should be considered when planning studies.
Status Assessment of the State-Threatened Gravel Chub (Erimystax x-punctatus) in Illinois
Authors: Jeremy S. Tiemann, Joshua L. Sherwood, and Andrew J. Stites
The Gravel Chub Erimystax x-punctatus (Family Leuciscidae) is an imperiled minnow with a disjunct distribution in Illinois. Due to its affinity for deep, swift flowing water, this species is often difficult to collect with traditional sampling methods and might be overlooked during fish sampling surveys. We performed a status assessment of this rare species with methods that target benthic-dwelling fishes by sampling at 50 sites throughout the species range. In non-wadeable areas, sites were accessed via boat and sampled using a mini-Missouri trawl, whereas in wadeable streams, sites were sampled by kick-seining swift-flowing rocky areas. Erimystax x-punctatus was found at 43% of the sites sampled – 41.3% of the sites trawled and 50% of the sites kick-seined – in depths varying from 0.3 to 2.1 m (mean: 0.78 m ± 0.39 m SD) and stream velocities ranging from 0.4 to 2.3 m/s (mean: 1.02 ± 0.45 m/s SD). Density estimates, defined as the number of individuals per 100-m² sampled, varied from 0.1 to 2.8 individuals (mean: 0.4 ± 0.79 individuals SD) during the project at positive sites. Our data showed that E. x-punctatus is still extant throughout the Rock River drainage and the mainstem Vermilion River (Wabash River drainage), and that this fish showed a strong attraction to high velocity areas over clean, rocky substrates.