Calanus finmarchicus egg production at its northern border

How the distribution of Calanus finmarchicus and its potential northward expansion will be affected by climate changes depends on the mechanisms and processes constraining their reproduction, recruitment and survival. Here we present measurements of C. finmarchicus egg production rates during the spring bloom in 2008, 2010 and 2011 in Disko Bay, West Greenland and validate four independently derived metabolic models to predict egg production rates.

The spring bloom in 2008 was short and intense and supported lower cumulated specific egg production of C. finmarchicus than the longer blooms with lower peak biomass in 2011 and 2012. The models predicted different timing of initialization and development of egg production rates based on phytoplankton biomass and temperature and model performance varied from ‘poor’ to ‘very good’.

Phytoplankton biomass controlled the changes in egg production rates during the spring in Disko Bay, while the low temperature in the Bay explained why the egg production rate here is much lower than at more southerly localities despite high food concentrations. This study suggests that an increase in magnitude of the Arctic phytoplankton spring bloom will not result in increased copepod egg production, whereas a longer bloom and increasing temperatures will