A quantitative survey of marine invertebrate communities inhabiting various shallow-water environments around Islas Cancun, Mujeres, and Contoy (State of Quintana Roo, Mexico) has yielded more than 300 species of benthic mollusks. Comparisons of molluscan life and death assemblages suggest that large-scale transport of shell material and mixing of faunas from different environments after death are negligible. Multivariate numerical analysis (cluster analysis and ordination) based on the presence and abundance of molluscan species in quantitative samples demonstrates that the same general associations tend to occur whether living animals only or dead remains only are considered.

Invertebrate death assemblages in this region, produced by the in-place accumulation of remains of living benthic populations, represent the total community composition and structure as they are sustained and enhanced through time. Thus, in many cases, the dead shells in the sediment (i.e., the future fossil assemblages) yield a more accurate picture of the whole benthic molluscan community than do one-time observations of the life assemblages.