Food Web
Pyramid of Numbers
This pyramid is a rough estimate of the number of organisms living in a square kilometer of Lake Superior relative to each other. There must be less organisms the higher you travel up trophic levels because there is only enough energy in an ecosystem to sustain so much life.
Pyramid of Biomass
This pyramid is a rough estimate of the total mass of the living things in a given part of Lake Superior in relation to each other.
Pyramid of Energy
This pyramid is an estimate of how much energy is available at each trophic level. About 90% of energy is lost between trophic levels. It is used for things like life processes like movement and reproduction. Because the amount of energy available at each level is less than the one below it, the diagram is always a pyramid.
Food Chain
Bioaccumulation of Toxic Substances
One of the main toxic substances that accumulates in Lake Superior is Mercury. There have been unsafe levels of it found regularly throughout commercial fish and game in the lake. Efforts to lower the levels are keeping researchers from finding where the bioavailable form of mercury (Methylmercury, MeHg) is produced from inside the ecosystem. Biomagnification makes it so that the algae has little amounts but as it condenses up the trophic levels all the way up to the Sea Lamprey which would consume high levels of toxic substances.
Keystone Species
Lake Trout
An example of a keystone species in Lake Superior is the lake trout. The lake trout is vital to the Lake Superior ecosystem because it is the main predator. The lake trout's role is to moderate populations of smaller fish by eating them. If the lake trout were to be removed, there would be an overabundance of smaller fish. These smaller fish would then cause a lack of producers, which in turn would create an imbalance of various things in the lake, greatly disturbing the ecosystem.
Symbiotic Relationship
Lake Trout and Sea Lamprey
An example of a parasitism in Lake Superior is the relationship between the sea lamprey and the lake trout. The sea lamprey will attaches to the lake trout and sucks the blood from it until the trout dies. The lamprey gains food/nutrients and the trout loses its life.
Predator Prey Relationship
Smelt Fish
In an ecosystem, when the predator population increases, the prey population decreases, and vice versa. If there are more predator to eat prey, the prey population will decrease. But when there are less prey(because they've been eaten), predators will begin to die out, and the cycle continues. An example of a predator-prey relationship in Lake Superior is the one between the smelt fish and the lake trout. In Lake Superior in the late 1950s – early 1960s, smelt fish abundance was at its maximum, wild lake trout was at its minimum, and the rate of lake trout hatching was increasing rapidly. Because there were so much prey to be eaten, predator populations could begin to thrive. More lake trout hatched, and the prey began to disappear.