Assemblages are from nearshore (intertidal and very shallow subtidal) and sublittoral environments, represent four biozones and four 3rdorder depositional sequences over more than three million years, and are developed along the same depth-related environmental gradient.
Differences between local assemblages were studied with species, genera and families, and using percentages, square-root- and fourth-root transformed percentages, and presence-absence data.
All taxonomic levels are useful to distinguish between localities, but species are generally better suited to than genera and families. Presence-absence data provide the best separation between local assemblages at all taxonomic levels, but environmental differences are evident: In nearshore assemblages at the species- and genus level, differences between localities strongly increase when moving from percentages to presence-absence, whereas in shelf assemblages the increase is moderate and peaks at fourth-root transformed data. This can be related to evenness, which is comparatively high in shelf assemblages.
Preliminary results show that in contrast to quantitative data that are reduced to presence absence data, the species lists from museum collections do not faithfully distinguish between localities and are therefore no good substitute for quantitative sampling.
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