Science / Medicine : Snails Pace the Recycling of Nutrients in Desert Soil

Rock-eating snails appear to make a critical contribution to the fertilization of desert soils by speeding the return of a valuable nutrient--nitrogen--to the ground. The snails dine on a diet of limestone rock containing lichens, a mixture of nitrogen-containing fungi and algae, and return the nutrient to the soil in their feces, contributing 11% of the nitrogen released into the desert soil each year, researchers reported last week in the British journal Nature.

Nitrogen, an element essential to all forms of life, continually cycles throughout ecosystems as plants absorb it from the soil and pass it to animals through food chains. Bacteria, in turn, break down plant and animal wastes, returning nitrogen to the soil. Scientists previously thought snails and other plant-eating animals, known as herbivores, played an insignificant role in the nitrogen cycle, said co-author Clive Jones of the Institute of Ecosystem Studies in Millbrook, N.Y.

The researchers studied the role of snails in nitrogen cycling in the Central Negev Highlands of Israel, a limestone rock desert.