When food is plentiful, the number of creatures who feed on it rises. But so does the number of creatures who feed on them, increasing the length of the food chain, ecologists have found.
Researchers at Rutgers University in New Jersey created an ecosystem of aquatic bacteria and protists in which they could alter the nutrients fed in.
They found that when the concentration of nutrients was high, several different links in the food chain could be sustained. Over time, a population explosion occurred at every level of life. But when the nutrient level was low, only the lower life forms survived.
From Nature 395, pp495-497