Two main types of phytoplankton have been decreasing in biomass in the North Atlantic by two per cent each year for the past 60 years, a new study has found.

Dalhousie University researchers analyzed data collected over more than half a century to assess how two types of phytoplankton — diatoms and dinoflagellates — are responding to climate change.

The analysis found that while the makeup and distribution of phytoplankton varied in different parts of the North Atlantic, overall, there was a decr…