Energy and the Great Lakes

Invasive species pose a threat to the stability of the Great Lakes.  They threaten the delicate balance that sustains life in the Great Lakes.  A good example of this is the Zebra mussel, a small mussel that is very successful in adapting to new environments.  According to the Great Lakes Science Center, female mussels can produce a million eggs each year.  They remove detritis and small organisms from the water, removing the bottom of the food chain and do this so proficiently that these tiny mussels can clean a gallon of water per day.  Combined with massive numbers they are a plague on the great lakes. 

So what does this have to do with energy?  Among the microscopic particles consumed by mussels are phytoplankton, a critical producer in the aquatic food chain.  Removing these in vast quantities prevents other species from eating sufficient food to survive.  The Zebra mussels have predators, but not enough to slow their explosive population growth.  An interesting fact noted by the Great Lakes Science Center states that Zebra Mussels have increased water clarity in Lake Erie from less than half a foot to over thirty feet in places.  This is a grim warning to the rest of the Great Lakes, with Zebra mussels cleaning water that rapidly and efficiently, they could turn the entire expanse of the Great Lakes into a sterile pool unable to support even the smallest native population.  The EPA states that at least twenty-five invasive fish species have flooded into the great lakes in the last two-hundred years.  Twenty-Five species, and a single mussel is capable of wiping out entire lakes, what could twenty-five do, just imagine it. 

As if things were not bad enough for the Great Lakes food web, another threat far larger than mussels and far more dangerous to man is coming.  Asian Carp, a  fish that, according to Time can weigh a hundred pounds.  While that statistic is alarming, the size of the fish is not the threat here, it is its eating habits.
According to the National Park Service a Grass Carp can eat forty percent of its body weight in plants a day.  "Asian carp grow fast, consume plants, mussels, snails, and plankton." (National Park Service)  Given this information, the carp could be a mixed blessing, they eat mussels and could combat the Zebra mussels, but the fact is they reproduce fast and will out-compete native species causing a wave of extinctions in the Great Lakes should they arrive.  As they feed on the lowest levels of the food chain, they represent a significant threat to the stability of the Great Lakes.


Sources:

http://www.glsc.usgs.gov/main.php?content=research_invasive_zebramussel&title=Invasive%20Invertebrates0&menu=research_invasive_i

http://www.epa.gov/glnpo/invasive/

http://www.time.com/time/health/article/0,8599,1962108,00.html

http://www.nps.gov/miss/naturescience/ascarpover.htm