Imagine you’re walking through a forest on a nice, sunny day in spring, natural light. spilling through the long tree branches and fresh air filling up the empty space. What you’re strolling through is a forest ecosystem. What you see are mostly fallen leaves, acorns, dirt, and twigs. It looks as if it had rained recently, as puddles and mud had formed on the path. There’s also a pond on your right, and lots of lime green algae float on top of the murky water. When algae grows like that, it’s called ‘blooming’. What you’re seeing is either the start of a good, healthy ecosystem, or a bad, unhealthy ecosystem.
Predators are organisms that eat other organisms. The organisms that they eat are called prey. Most animals, like tigers, eat live prey, but prey do not have to be alive; vultures are large, scrawny birds that are scavengers, meaning they eat dead animals.
When an ecosystem’s predator and prey relationships are balanced, that means the predators have enough prey to eat, and the prey consume enough to survive. An unbalanced ecosystem means that the predators in that area don’t have enough prey to feed on, and the prey populations are decreasing.
In an healthy pond ecosystem, much like the one you imagined, the algae growing on top of the water thrives. The fish that eat it can also flourish. In this example, the fish is a predator, and the algae is the prey. The fish thrive off the algae, and the algae can live because of the nutrients in the pond water that it uses to grow. The turtles that eat the small fish can thrive too, because they have enough prey to eat. Herons that eat the turtles flourish as well, because as algae grows, the fish eat the algae and cause an increase in the fish population. The turtle population will also grow larger, which will allow the herons that eat turtles to have enough prey to feed on. This is an example of a healthy ecosystem, where the predator and prey relationships are balanced.
However, in an unhealthy ecosystem, all the algae that grow in the pond would suddenly die because there are no nutrients in the water left to support its life. Then, the fish in the pond will starve, and their population will begin to decrease. Another reason that would cause the fish to die would be that decomposers in the pond would take up much oxygen decomposing the dead algae. This leaves the fish with little oxygen to breathe, causing a decrease in the fish population. Turtles that eat the fish will die too, because of lack of prey. When the turtle population decreases, herons that eat them will also become hungry, and eventually the heron numbers will drop until there are very few of them left in the ecosystem. Then, turtle populations will increase rapidly, due to the significant loss of many predators. But the turtles also have to deal with another problem once their population increases. Food is scarce. The fish population is very low because of the reduced amount of oxygen in the water, so the turtles do not have enough food to eat. As a result, their numbers will also drop.
You see that if just one part of the food chain breaks (or in other cases, leaves the ecosystem), the whole food web and life of the ecosystem will fade. Predator and prey relationships must remain balanced, because the ecosystem life depends on these relationships in order to survive. Now that you know what an ecosystem is and how relationships work to benefit the organisms, it’s time for you to think about how to help one!