Publication Abstract

Title: A quantitative comparison between the sampling efficacy of the mini Hamon grab and the Costerus twin grab

Publication Abstract: The newly-developed Costerus twin grab was field-tested to ascertain both its sampling efficacy and the compatibility of faunal and particle size distribution datasets resulting from its use with similar datasets derived from deployments of the mini Hamon grab.

The Costerus twin grab samples with a single bucket a consistently larger volume of sediment than the mini Hamon grab, resulting in an increased sampling effort of macrobenthic infauna. As a result, benthic assemblage metrics that rely directly on counts of organisms and species are altered significantly by this increase of effort. Metrics that are relatively more sampling-effort independent, such as some multivariate indicators, are less affected by the evident increase in sampling effort. Ecological assessments using datasets from both grabs must acknowledge such differences and analyse the data accordingly.

In areas of mixed sediments, particle size distribution patterns were found to be the same regardless of whether the entire contents of a Costerus bucket were analysed or just a sub-sample. Sampler choice did not affect particle size distribution patterns.