Unexpected decoupling between biodiversity and standing stocks in marine calcifying phytoplankton

For many ecosystems, biodiversity promotes productivity. Global biodiversity loss due to anthropogenic climate change has thus raised concerns about its resulting impact on productivity since ecosystem services like carbon sequestration are key in limiting climate change. Our oceans are especially important in this context, as they sequester more carbon than terrestrial ecosystems. Nonetheless, our understanding of how biodiversity relates to productivity in oceanic ecosystems is limited and hitherto undescribed for coccolithophores, a main ocean calcifier which plays a key role in the ocean carbon cycle. Here, by combining a new comprehensive coccolithophore abundance data set and species distribution models we illustrate that biodiversity is decoupled from standing stocks for coccolithophores. We show this is because the processes driving coccolithophore diversity do not influence coccolithophore standing stocks. Our results contribute new knowledge about the relationship between productivity for a key marine planktonic microorganism, highlighting that diversity loss due to anthropogenic carbon emission does not necessitate reduced ocean standing stocks and productivity. This result is important for climate models, suggesting that they do not need to capture our ocean’s full diversity to capture key biogeochemical processes such as calcification and carbon fixation.