Influences of Vegetation and Abiotic Environmental Factors on Salt Marsh Invertebrates

Abstract

Sediment-dwelling fauna are a ubiquitous component of salt marshes yet we have limited understanding of their roles in marsh functioning and of the environmental conditions that control their distributions and abundances. This paper examines the influence of vegetation (presence, type, density, and biomass) and other environmental variables (marsh age, sediment and porewater properties, elevation, flow, oxygen, and biogenic structures) on salt marsh macrofauna and meiofauna. We review studies from a variety of geographical locations and include new information from systems with adjacent natural and restored sites in southern California. The influence of environmental factors on faunal assemblages varies with marsh system, factor intensity or concentration, taxon studied, and with other interacting factors present. We hypothesize a hierarchy of environmental variables in which abiotic properties such as marsh age, elevation and salinity act over large space and time scales, and are most likely to influence the presence or absence of species. Sediment properties (organic matter and particle size) and vegetation presence or type act on intermediate scales affecting macrofaunal abundance and composition. Plant biomass, culms and biogenic structures generated by fauna are patchy and act on small scales, often interacting with flow, to affect distribution and abundance patterns. Resolution of these processes in salt marshes should improve our understanding of controls on invertebrate communities and will ultimately aid the conservation and restoration of salt marsh habitat.