MadSci Network: Environment & Ecology

Re: How is it possible to keep the food web going?

Date: Mon Nov 30 16:38:14 1998
Posted By: Rob Campbell, Grad student, Biological Oceanography, Dalhousie University
Area of science: Environment & Ecology
ID: 910802596.En

Hi Kate-

You've asked two very good questions; I'll deal with them one at a time.

How is it possible to keep the food web going?

All food webs are ultimately powered by the sun. Plants absorb light energy from the sun and turn it into chemical energy, in the form of sugars in the process of photosynthesis. The sugars are made up of carbon, hydrogen, and oxygen, which the plant gets from carbon dioxide (which it gets from the air), and water (which it gets from the air and soil.) Plants are eaten by herbivores and used to make more herbivores, and the herbivores may be eaten by carnivores. All plants, herbivores and carnivores respire, which is essentially the opposite of photosynthesis- where sugar and oxygen are turned into energy, carbon dioxide and water, which is just what the plants need for photosynthesis! So, as long as the sun keeps shining, plants will continue to make sugars, and food webs will continue to exist. No worries there!

What are some ways to prevent living creatures and plants dying or being harmed due to the UV-B Rays that filter through the Ozone Layer?

Plants and animals have lots of neat ways to deal with UV radiation. Some plants and animals produce pigments, which protect them from UV. These pigments protect the animal, by reacting with the incoming UV radiation, effectively turning it from light energy into heat energy. Unfortunately, with the recent reduction in the amount of atmospheric ozone, there is more UV making its way through the atmosphere to the planet. While some plants and animals may be able to cope with the higher levels of UV, a lot will not. In order to prevent plants an animals being harmed by UV, we must prevent the UV from reaching those plants and animals in the first place, that is to prevent the UV from ever reaching the surface of the earth. The ozone layer does a pretty good job of that, if there's enough of it. Right now there are a lot of people in a lot of independent and government agencies trying to figure out how we can stop losing the ozone we've got now- this has lead to a number of laws aimed at stopping the production of chemicals that destroy ozone, such as the CFCs (ChloroFluoroCarbons) which used to be found in refrigerators and aerosol spray cans. Hope that helps, MAD Scientist Rob Campbell

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