Biological Communities and the long term effect of invasive species

In today's blog, the following topics will be discussed:  Biological communities, Species interactions, Evolution, and The effects of Invasive species in the Great Lakes on these fronts.  It is important to note that an invasive species has several critical advantages over Native Animals.  Native Animals have exact spots in their food webs, that they evolved specifically for.  They have designated predators and or prey.  So there are restrictions on their population.  Invasive species that manage to gain a foothold tend to be very successful.  If they can find a decent food source they tend to lack predators leading to a population explosion.  If left unchecked they will wipe out their competition.  This can have a devastating effect on the entire food web.  In the great lakes this is becoming a real problem as two of the most devastating invasive species feed on the bottom-most level of the food web.  This effects the entire population of the great lakes, nothing is immune to these animals.  I am of course referring to Asian Carp and Zebra Mussels.  These invasive species are competing for Niches occupied by Native Species, and are quite successful.  What this means is that if this current trend continues, we could witness a total collapse of the great lakes food web.

According to asiancarp.org, the Asian carp will compete with smaller native fish such as the Cisco, Bloater, and Yellow Perch.  These small fish in turn provide the food for larger fish such as Lake Trout and Walleye.  (asiancarp.org)  Even This minor example shows the danger.  These 5 species could easily become extinct, but what does that mean for the Great Lakes.  Larger Predators like Trout or Walleye keep the populations of smaller fish in check, if they were to disappear, there would be no population checks on smaller fish which would lead to a population explosion among smaller fish.  This would in turn deplete the remaining food source even more rapidly.  More fish competing for less and less food.  Of course this is not very likely as the asian carp would probably outcompete the smaller fish first and then the larger predators would disappear.  But what would this mean?  It would mean a total meltdown of the Food web in the great lakes and the death of many Animals that depend on the Great Lakes for food.  This problem is increased when you consider that Asian carp will also be wiping out plants and feeding on phytoplankton.  With less oxygen production in the Great Lakes, species would be hard pressed to survive.  That and the fact that Zebra mussels, which are very similar to Carp in their effects on the great lakes, are also a threat facing the great lakes.  The two species in combination could trigger a wave of mass extinction that could wipe out thousands of years of evolution.  (the great lakes are are relatively new feature to the North American continent, carved out by glaciers during the ice ages, so they have not had a large amount of time in which evolution could occur).  According to asiancarp.org, the establishment of a sustainable population of invasive species is dependent on predator-prey interactions, food availability, and other various factors.  (asiancarp.org)

According to ScienceDaily.com, the real threat is not what they will do to the great lakes as a whole but what they will do to the shore area, to the tributaries that enter the lake.  Such areas are key breeding grounds for smaller fish.  The carp could wipe out the food in these areas and cause tremendous damage to both aquatic species and any terrestrial species that rely on the Great Lakes for food.  This fact is backed up by Csmonitor.com who state that successful invasive species breed fast, and eat a lot. (Csmonitor.com).  According to Csmonitor.com, asian carp can carry a million eggs in a lifetime, and eat a lot, so a small population of these large fast breeding fish could grow rapidly to become a real problem.



Resources:

http://asiancarp.org/background.asp

http://asiancarp.org/frequently-asked-questions/

http://www.sciencedaily.com/releases/2011/06/110630112859.htm

http://www.csmonitor.com/USA/2010/0316/Asian-carp-how-one-fish-could-ruin-the-Great-Lakes

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

Choosing a topic

This blog will discuss many of the following topics: the effects of invasive species on the native population and the health of the lakes in general, The various invasive species themselves, and measures to reduce or eliminate them from the great lakes.  Zebra mussels, Asian Carp, lampreys, and other invasive species threaten the great lakes.  Mussels, and Asian Carp represent a significant threat as they remove phytoplankton, zooplankton, and detritus which represent the bottom of the aquatic food chain.  They could turn the great lakes into a sterile pool of water unable to support life unless something is done to check their populations.

Until next time,

Brian Kober