Characteristics of egg production of the planktonic copepod, Calanus finmarchicus, on Georges Bank: 1994–1999

Disentangling the mechanisms behind climate effects on zooplankton

“…The environmental variables are recorded during this period in spring; thus, the observed associations might reflect effects on egg production by the parent generation or on early growth conditions for copepodites sampled in summer. However, most field studies to date have indicated that food availability is more important for C. finmarchicus egg production than direct effects of temperature (12,44); in particular, phytoplankton availability seems to benefit egg production (45). In light of the negative association between mean spring temperature and yearto-year variation in summer biomass, we hypothesize that the locally positive temperature−biomass association is driven by the spatial patterns in C. finmarchicus biomass in spring, with higher biomass in warmer, southwestern areas.…”

Impact of bio-physical feedbacks on the tropical climate in coupled and uncoupled GCMs

“…In order to further evaluate the performance of the biogeochemical model, the dominant modes of chlorophyll and associated SST patterns are analyzed from both model and observations. Previous studies reported that the first and the second mode of chlorophyll in the tropical Pacific are associated with the mature and decaying phases of ENSO cycle, respectively (Yoder and Kennelly 2003;Runge et al 2006;Park et al 2011). Figure 2a-f are the spatial patterns of observed chlorophyll and SST, respectively, regressed onto the first principle components (PC) of tropical chlorophyll at 3 different time-lags.…”

Biogeography of key mesozooplankton species in the North Atlantic and egg production of <i>Calanus finmarchicus</i>

“…They also found that over 24 to 72 h periods, groups of females in screened cylinders within large volume chambers (Method C) gave higher egg production rates than those in chambers without screens (Method E) did. Runge and Roff (2000) reported that egg laying in dishes (Method A) yielded similar egg production rates to the egg laying of groups of 10-15 females incubated in 1.5 L screened beakers (Method C). However, the beaker egg production estimates declined dramatically relative to dish estimates in rough weather, presumably due to increased mixing in beakers and therefore higher loss due to cannibalism.…”

“…Previous studies of egg production have shown a significant link between clutch size and female size (Runge and Plourde, 1996;Campbell and Head, 2000;Jónasdóttir et al, 2005;Runge et al, 2006), and most of the data sets provided for this work included measurements of the prosome lengths for each individually incubated female for each egg production experiment, along with each corresponding individual clutch size . One exception to this was in the SNWS region (data from Ocean Weather Station M), for which average female prosome lengths were determined for groups of females that had not been used in experiments but that had been collected on the same day.…”

“…Because of the potential for diel egg-laying behaviour, the vast majority of egg production experiments have been carried out by incubating freshly caught females for 24 h. It has been shown that female Calanus that are kept and fed in vitro and then transferred to an incubation chamber lay the same number of eggs over the next 24 h whether or not they are fed (Plourde and Runge, 1993;Laabir et al, 1995). Thus, it has been assumed that average egg production rates of freshly caught females are the same during the 24 h following capture as they would have been in situ (Runge and Roff, 2000). In this study we include only results from such 24 h incubation experiments, and we term the eggs laid during these 24 h periods "clutches", even though they may originate from more than one spawning bout, and we refer to the number of eggs laid by one female during a 24 h period as the clutch size (CS).…”