Propagation of an atmospheric climate signal to phytoplankton in a small marine basin

Abstract

A 14‐yr record of weekly observations in Bedford Basin (Canada) was used to describe the direction and magnitude of departures from long‐term mean conditions in both climate and plankton components, for the purpose of detecting common patterns. Seasonal vertical stratification of the water column is determined primarily by temperature, but multiyear change in the annual deseasonalized average stratification is induced by salinity, which is linked to precipitation and river discharge. Stratification anomalies explain significant amounts of variability in the anomalies of nutrients and total phytoplankton biomass, especially that contributed by diatoms, but not the biomass of nanophytoplankton and picophytoplankton. Instead, the responses of the small phytoplankton groups appear directly related to temperature. Trophic linkage between phytoplankton and copepods is not statistically demonstrable, but there is strong evidence of linkage between phytoplankton and bacterioplankton. Temporal sign switching, which is the coherent departure from norm in both an ecosystem driver and response, strongly indicates the propagation of an atmospheric signal to phytoplankton in surface waters of Bedford Basin and thence further through trophic linkage and export.