Invasive species and waste

In the Great Lakes, we have two problems.  The first in that in the past, raw sewage has been dumped into the Great Lakes from overflowing sewers and deep tunnels.  Our waste treatment plants cannot handle the water pumped in during storms, so in the past sewage has been dumped untreated into the Lakes.  This is a huge environmental problem as this waste is hazardous, disease is a very real threat.  The 1993 Cryptosporidium outbreak was proof enough of this.  The threat of waste water being dumped into the Great Lakes is a very real threat to the health of all those who call the Great Lakes region home.  The second problem facing our Great Lakes is invasive species, threatening the survival of local species.

So how do these two problems relate to each other?  A notorious invasive species, Asian carp, was introduced to the United States by southern fisheries as an experimental waste treatment program.  The fish eventually escaped (or were released), and have spread north the the very edge of our Great Lakes spreading like wildfire.  Why are Asian carp such a threat?  Asian carp are large fish that consume large amounts of plankton, detritus, and will even consume sewage.  The are a fish that will eat anything and can live in terrible water conditions.  They breed in huge numbers, and when fully grown have few if any predators.  Asian carp can choke out all other composition in rivers and lakes by consuming the lowest level of the food chain more efficiently than native species can hope to compete with.

As if Asian carp were not bad enough, zebra mussels are even more efficient at cleaning water.  While they can also remove pollution, the fact is they can sterilize a lake.  They have already wreaked havoc in Lake Erie and are spreading like a plague.  Few predators and rapid population growth combined with the ability to filter water leaving almost nothing for other animals to consume means this mussel poses a massive threat to the stability of the Great Lakes.

There are positives and negatives to invasive species.  They can deal with pollution and clean our lakes.  That is a positive.  The negative is that they are so efficient at it that they may very well sterilize the Great Lakes leaving behind sterile pools of water incapable of supporting life.  The threat invasive species pose is a very real threat that cannot be ignored.

Sources:
http://www.mkelgbthist.org/events/health/crypto.htm
http://eattheinvaders.org/asian-carp/
 http://www.protectyourwaters.net/hitchhikers/mollusks_zebra_mussel.php