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Lethal Effects Of Leaf Leachate From The Non-Native Invasive Shrub Amur Honeysuckle (Lonicera Maackii) On A Model Aquatic Organism (Hyalella Azteca), Eric B. Borth, Kevin W. Custer, Ryan W. Mcewan Apr 2018

Lethal Effects Of Leaf Leachate From The Non-Native Invasive Shrub Amur Honeysuckle (Lonicera Maackii) On A Model Aquatic Organism (Hyalella Azteca), Eric B. Borth, Kevin W. Custer, Ryan W. Mcewan

Ryan McEwan

The invasive shrub Lonicera maackii (Amur honeysuckle) is a problematic species in the eastern United States and there is growing evidence that materials from this species have toxic effects on some organisms. We used a sequence of microcosm bioassays to assess the influence of L. maackii leaf leachate on the macroinvertebrate Hyalella azteca, which is a standard aquatic organism for toxicity assessment. In a laboratory setting, H. azteca were exposed to a leaf leachate dilution series (6.25%, 12.5%, 25%, 50%, 100%) in 48-h toxicity tests. This was repeated throughout the growing season to assess the potential for changes in …


Lethal And Sublethal Effects Of Novel Terrestrial Subsidies From An Invasive Shrub (Lonicera Maackii) On Stream Macroinvertebrates, Ryan W. Mcewan, Kevin W. Custer, Eric B. Borth, Sean D. Mahoney Jan 2018

Lethal And Sublethal Effects Of Novel Terrestrial Subsidies From An Invasive Shrub (Lonicera Maackii) On Stream Macroinvertebrates, Ryan W. Mcewan, Kevin W. Custer, Eric B. Borth, Sean D. Mahoney

Ryan McEwan

The biology of headwater streams is intimately linked to that of the surrounding terrestrial environment through organic matter subsidies. Lonicera maackii, an invasive shrub that is becoming abundant in headwater stream riparian areas, deposits substantial quantities of organic matter into the aquatic system. This organic material has allelopathic effects on terrestrial plants and insects, and a growing body of work suggests strong connections between L. maackii invasion and aquatic biota. Lonicera maackii deposits fruit and flowers in quantities and timings that are unique, and we tested the hypothesis that these subsidies would negatively affect survival and growth of laboratory-cultured …


The Role Of Environmental Filtering In Structuring Appalachian Tree Communities: Topographic Influences On Functional Diversity Are Mediated Through Soil Characteristics, Julia I. Chapman, Ryan W. Mcewan Jan 2018

The Role Of Environmental Filtering In Structuring Appalachian Tree Communities: Topographic Influences On Functional Diversity Are Mediated Through Soil Characteristics, Julia I. Chapman, Ryan W. Mcewan

Ryan McEwan

Identifying the drivers of community assembly has long been a central goal in ecology, and the development of functional diversity indices has provided a new way of detecting the influence of environmental gradients on biotic communities. For an old-growth Appalachian forest, we used path analysis to understand how patterns of tree functional diversity relate to topography and soil gradients and to determine whether topographic effects are mediated through soil chemistry. All of our path models supported the idea of environmental filtering: stressful areas (high elevation, low soil moisture, low soil nutrients) were occupied by communities of low functional diversity, which …