Rates of egg production, grazing and mortatlity of Calanus finmarchicus measured experimentally in the North Atlantic during the Maria S. Merian cruise MSM26, spring 2013

An incubation experiment at five different temperatures was used to assess the potential for adaptation of Calanus finmarchicus to future warming of the ocean. During a short term (3 h) and long term (6 day) exposure of individual females to a gradient of temperature stress, egg production and fecal pellet production were monitored to indicate secondary production and grazing rates. A longer term (10 day) exposure to elevated temperatures followed by a return to ambient sea temperatures was used to assess the potential recovery of individuals exposed to temperature stress. Females were picked out from WP2 net samples and acclimatised in 2 L bottles of GFF filtered seawater with Thalassiosira weissflogii as prey for >48 h at ambient SST. Experimental bottles were filled with filtered seawater (GFF filtered from non-toxic seawater supply) and acclimated to experimental temperature overnight (0, 5, 10, 15 and 20 °C). Individual females were transferred into bottles using forceps and the bottles were inoculated with T. weissflogii to a final concentration of 5 µg chl L-1. Bottles were then placed into water baths and incubated for 3h or 6 d, and monitored for egg and fecal pellet production rates. A 10 day exposure experiment was used to test the potential for recovery from temperature stress, by returning females incubated at 5, 10, 15 and 20 °C back to 10 °C for 24 h and counting egg and fecal pellet production.