the effect of aquatic plant abundance on shell crushing resistance in a freshwater snail水生植物丰富度的影响在淡水蜗牛壳破碎阻力.pdf

The Effect of Aquatic Plant Abundance on Shell Crushing Resistance in a Freshwater Snail 1 1 ´ ´ 2 1 Johel Chaves-Campos , Lyndon M. Coghill , Francisco J. Garcıa de Leon , Steven G. Johnson * ´ ´ 1 Department of Biological Sciences, University of New Orleans, New Orleans, Louisiana, United States of America, 2 Laboratorio de Genetica para la Conservacion, Centro ´ ´ de Investigaciones Biologicas del Noroeste, La Paz, Baja California Sur, Mexico Abstract Most of the shell material in snails is composed of calcium carbonate but the organic shell matrix determines the properties of calcium carbonate crystals. It has been shown that the deposition of calcium carbonate is affected by the ingestion of organic compounds. We hypothesize that organic compounds not synthesized by the snails are important for shell strength and must be obtained from the diet. We tested this idea indirectly by evaluating whether the abundance of the organic matter that snails eat is related to the strength of their shells. We measured shell crushing resistance in the snail Mexipyrgus churinceanus and the abundance of the most common aquatic macrophyte, the water lily Nymphaea ampla, in ten bodies of ´ water in the valley of Cuatro Cienegas, Mexico. We used stable isotopes to test the assumption that these snails feed on water lily organic matter. We also measured other factors that can affect crushing resistance, such as the dens