Many organisms make up a food web. The web is rather complex as we draw food chains to different decomposers to producers to predators. All the organisms need each other to keep each other healthy and stable in the ecosystem. What happens if an organism goes extinct in a food web? If one species in the food web ceases to exist, one or more members in the rest of the chain could cease to exist too. For example: The harelip sucker fish, used to eat snails in the 19th century. After waste, topsoil and other debris invaded rivers where the fish lived, the snail population dwindled. The scientists noted that this decline probably caused the fish to go extinct. Polar bears, for example, rely on seals for food. The seal population may decline if Arctic cod, a key food supply for seals, dwindles. Cod eat zooplankton, and zooplankton eat ice algae. If climate change causes sea ice to melt, the ice algae population drops, creating a cascading effect that causes the polar bear population to dwindle and eventually the polar bear becomes extinct. Humans also affect the food web in other ways. Overfishing occurs when people take too much food from the oceans, and species can't replace themselves. Atlantic cod almost became extinct in the 1900s when fishermen removed too many of those fish from the sea We can't control weather but, weather changes cause negative effects in the food web. As water temperature in the ocean rises, the supply of corals decreases. Because other marine life forms live in coral reefs, fewer reefs will lead to disruptions in the food web for creatures that live in the ocean. These food web effect examples show what happens when the bottom of the food web is disturbed or destroyed. Let's look at what happens when the food web is disturbed from the top down. Some of the world’s top predators - including lions, wolves and sharks - are in sharp decline. In East Africa’s Serengeti plain the ripple effect of rinderpest disease on the plant-eating wildebeest and the overgrowth of grasses caused a problem. “The disease, by reducing the abundance of these large animals, causes the vegetation to increase, thus increasing the intensity and frequency of wildfire.” As soon as the rinderpest disease was gotten rid of, the wildebeests populations grew back quickly and soon grasses were maintained, the fire hazard was downgraded. Elsewhere in Africa, the loss of lions, leopards, wild dogs and hyenas has allowed baboons to increase in number, which has created another set of problems. “The increasing baboon populations have spread into areas of increased human contact that has caused the frequency of intestinal parasites in both the baboons and in people because of the overlap of these two species now.” More and more scientific studies are showing that when food webs are disturbed from the bottom or the top, great consequences occur. And that's serious for every ecosystem. Basically, all these animals need each other to survive. Humans need to think about every step they make when disturbing an ecosystem....that's why you are learning this in the 6th grade. It's entirely possible the animals you knew as a child won't be found anywhere....
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Mrs. TaylorI love science! Everything about the world is interesting and never boring. I love to study plants, animals, insects, and people. My favorite subjects are my students who are the most unique organisms on the planet! Categories |