Characteristic benthic size spectra: potential sampling artefacts

Simple mathematical simulations were carried out to examine the potential influence of sampling protocol on the production of characteristic benthic size spectra (in biomass and species richness). The use of separate samples and sieve meshes for meio- and macrobenthos readily produced a biomass trough at intermediate body sizes where no trough existed in the sampled population (set by simple body size-abundance allometry). The number of specimens sampled per size class was also bimodal across the meio- to macrobenthos size range, providing a simple mechanism by which bimodal species size spectra may result, i.e. a general positive relationship between estimated species richness and the number of specimens examined. These sampling artefacts have the potential to generate characteristic benthic biomass and species size spectra that reflect the sampling protocol rather than the underlying structure of the benthic community. The results suggest the need for caution in regarding the meio- and macrobenthos as coherent entities with distinct ecological attributes. They also raise the prospect of a useful, single mathematical formulation of standing stock and body size for the metazoan benthos as a whole in biogeochemical modelling.