Copepod feeding and reproduction in relation to phytoplankton development during the PeECE III mesocosm experiment

• Main Authors: Carotenuto, Y., Putzeys, S., Simonelli, P., Paulino, A., Meyerhöfer, M., Suffrian, K., Antia, A., Nejstgaard, J. C.
• Format: Text
• Language: English
• Published: 2018
• Subjects: Calanus finmarchicus
• Online Access: https://doi.org/10.5194/bgd-4-3913-2007; https://www.biogeosciences-discuss.net/bgd-2007-0147/

Within the frame of the Pelagic Ecosystem CO 2 Enrichment (PeECE III) experiment, reproduction and feeding of the copepod Calanus finmarchicus was monitored in relation to phytoplankton development in two mesocosms, at present 1× (350 μatm) and ca 3× present (1050 μatm) CO 2 concentrations, respectively. Both mesocosms showed rapid phytoplankton growth after the initial nutrient additions and reached maximum chlorophyll (Chl) a concentrations around day 10. Flow-cytometry and specific pigment analysis (HPLC-CHEMTAX), showed that diatoms and prymnesiophyceae ( Emiliania huxleyi (Ehux) and other nanoplankton) dominated the biomass. Feeding and egg production rates of C. finmarchicus developed similarly in both mesocosms, and were positively correlated with Chl a , Ehux, diatom and prymnesiophyceae concentrations. Although the total number of copepod nauplii recruited during the experiment was similar in 1× and 3×, significantly less nauplii were recruited in 3× during the peak of the bloom compared to in 1×. We conclude that the algae responsible for the higher biomass in 3× during the peak of the bloom (diatoms and Ehux), may have been relatively inferior food for C. finmarchicus naupliar recruitment, possibly due to a high C:N ratio (>8). Nevertheless, the 3 fold increase in CO 2 concentration did not show any clear overall effect on bulk phytoplankton or zooplankton development over the whole experiment, suggesting a more complex coupling between increased CO 2 and the nutritional status of the system.