Ecological stoichiometry of the salt marsh: Silicon:nitrogen and effects on the lower food web

Salt marshes have been subject to anthropogenic perturbations, such as cultural eutrophication, that alter nutrient loading ratios. Diatoms are important components of the algal assemblage in salt marshes, contributing directly to marsh primary production and estuarine secondary production. Diatoms require a 1:1 Si:N to grow and Si:N differing from one may shift the algal assemblage toward one favored by nuisance filamentous algae. I tested through in-situ experimentation whether Si:N greater and less than one affected the algal assemblage by decreasing diatoms. Through a Melampus bidentatus growth experiment I tested how a diet of diatoms, green filamentous algae or a mixture of both, in low and high quantities would affect the growth and survivorship of the snail. I found analysis of benthic chlorophyll is not a good proxy for total benthic algal or diatom biomass, and suggest that algal counts be done. The diatom diet appeared to be the highest quality; M. bidentatus that consumed only diatoms did not lose weight and had 100% survivorship.;Key words: salt marsh, stoichiometry, silica, nitrogen, diatoms, Melampus bidentatus, periphyton...