Technical Note: The Use of Laser Diffraction Particle Size Analyzers for Inference on Infauna-Sediment Relationships

Abstract

For over a century, ecologists and evolutionary biologists have investigated the association between sedimentary characteristics and the infaunal communities inhabiting sediments. Relationships between infauna and, specifically, sediment grain size distributions, have provided a common methodology to predict the distributions, composition, and diversity of soft-sediment communities. Wet/dry sieve methods have traditionally been used to determine grain size distributions, but laser particle size analyzers are becoming increasingly popular and have been shown to measure sediment grain size distributions more efficiently and more accurately than wet/dry sieve methods. An additional, but underexplored, advantage of laser particle size analyzers is their ability to provide uncommonly reported or alternative grain size statistics that can be used to estimate sediment characteristics that are not easily measured using sieve techniques. In particular, measures of sediment heterogeneity are arbitrary and tedious to measure with previously used sieve and microscope techniques. Here, we propose that grain size coefficient of variation, measured using a particle size analyzer, is an improved metric for sediment heterogeneity. We show that grain size coefficient of variation is related to infaunal richness in intertidal habitats along the northern Gulf of Mexico matching previous results relating sediment heterogeneity to infaunal richness. We discuss the benefits and drawbacks of particle size analyzers and how the use of alternative metrics from laser particle size analyzers may assist the field of benthic ecology.