Ecological equivalence of species within phytoplankton functional types

There are tens of thousands of phytoplankton species and local communities frequently contain dozens of species. Despite this diversity phytoplankton are often aggregated into a few functional types according to metabolic traits or biogeochemical role. The phytoplankton functional type approach assumes that all species within a functional group behave similarly. Using the L4 Western English Channel time-series we test if the dynamical behavior of a species’ biomass is random within its functional type biomass envelope. We find that most species behave randomly within their functional type most of the time. This analysis shows that in a community that most species belonging to the same functional type are ecologically equivalent, which supports the approach of using phytoplankton functional types to model complex phytoplankton communities.