COMPARING THE DEEP SEA ROCK AND FOSSIL RECORDS OF COCCOLITHOPHORES AND PLANKTIC FORAMINIFERA

The deep-sea record of Coccolithophores and planktic Foraminifera provides an unrivalled source of data on evolutionary patterns and the ocean plankton’s response to global change. However, while individual sites can give excellent high-resolution records of biological succession, when global or ocean-wide biodiversity patterns are compiled summarizing data from multiple sites, sampling bias needs to be considered. The deep-sea record of microfossils is accessible from only a relatively small number of drill sites, which has the advantage of allowing sampling effort to be readily quantified. Here we test the effect of sampling bias on the patterns of coccolithophore and planktic foraminiferal diversity using a new taxonomically standardized database comprising 40,494 deep-sea species occurrences from late Jurassic to Pleistocene sediments of the North and Central Atlantic (including the Mediterranean and Caribbean). We demonstrate that sampling and richness are highly correlated over both long-term and short-term timescales and further that a model assuming true diversity is constant can predict much of the observed pattern through sampling bias alone. Nuances to this pattern include a lower apparent bias in planktic Foraminifera and an overall decoupling of richness and sampling in the Neogene where sampling is particularly high. Our analyses demonstrate that sampling plays a role in shaping ocean-wide richness counts of two major calcareous plankton groups.