The cascade of effects that result from the presence of a tiny invasive species can be fascinating, surprising, and maybe more extensive than one would expect. In this case, scientists found that the effects were much like that of the proverbial iceberg – only a small percentage of the impact from this invasive insect, the hemlock woolly adelgid ( Adelges tsugae ), occurs above ground in the tree this species infests; the rest of the impacts lie below the surface in the groundwater, soil quality Topics: Insects, Water, Coweeta Hydrologic Laboratory, Hemlock Woolly Adelgid, Invasive Insect, North Carolina, Photosynthesis, River Ecosystems.