Newly encouraged problems in nature - Asian carp an invasive species: the Asian/silver carp - actually several species of carp - first presented to the United States in the 1970s in the Mississippi River around Mississippi/Alabama and have since gained latitude now reaching as far north as Minnesota by way of river lock systems.  In general, concern for invasive species seems to be overlooked, at least by the general public, until the economic burden is staggering.  The Asian/silver carp primarily causes economic damage by out competing native fish and thereby disturbing the fishing industry.  

An example of globalization making something worse.

Additionally, zebra mussels in Lake Michigan (originally from the lakes of southern Russia and Ukraine) continue to cause significant economic burden.  Not to mention the goby fish (originally from the Caspian and Black Seas), known to carry a strain of botulism responsible for killing thousands of shorebirds along Lake Michigan.  Internationally, Korea has the same problem with bluegill, bass (originally from the United States).

Adult bighead carp, underwater image of an adult bighead carp, photo by Ryan Hagerty/USFWS.

B4E3A80A-F37C-4E95-9092-A784042B6C17Adult bighead carp Underwater image of an adult bighead carp. Photo by Ryan Hagerty/USFWS