On birth and death in the sea

By M. Ohman, J. Runge, E. Durbin, D. Field, B. Niehoff. Hydrobiologia, 2002

112 citations recorded by the source corpus.

We present the first comparative study of the stage-specific patterns of mortality of Calanus and Pseudocalanus, two widely distributed genera that are representative of a relatively large-bodied, broadcast spawning calanoid copepod and a relatively small-bodied, egg-brooding calanoid. The study site is Georges Bank, a continental shelf locality in the Northwestern Atlantic with retentive circulation that renders it suitable for studies of population dynamics. Based on extensive mortality estimates from 30 cruises, we find that co-occurring Calanus finmarchicus and Pseudocalanus spp. have markedly different patterns of stage-specific mortality, the former bimodal and the latter relatively uniform with respect to developmental stage. Neither taxon exhibits a monotonic decline in mortality with developmental stage, nor are rates of mortality predictable in a useful manner by copepod body size or by ambient temperature. Young stages of the broadcast-spawning C. finmarchicus show conditional density-dependence of mortality rates, i.e. mortality rates are independent of population density when adult females are low in abundance but positively related to population density at high female abundances. This density-dependence, which is probably attributable to egg cannibalism, introduces a quadratic mortality term into population dynamic models. The egg-brooding Pseudocalanus spp., in contrast, show no evidence of density-dependent mortality. The two taxa illustrate a life history trade-off: the broadcast-spawning Calanus exhibits birth rates that are greatly elevated with respect to those of Pseudocalanus, but there is a compensatory cost in very low survivorship of the freely spawned eggs. Both the high fecundity, high mortality life history of Calanus and the low fecundity, low mortality life history of Pseudocalanus appear to have approximately equal fitness in this study site.

Subfields: Ecology, Global and Planetary Change, Oceanography

View Paper: https://www.semanticscholar.org/paper/4516d49becfaf0d09bd8779ac7408d3db7bb48c3

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Ecology

1. J. Runge
2. K. Eiane
3. P. Pepin
4. S. Plourde
5. E. Head
6. C. Johnson
7. E. Durbin
8. M. Ohman

In Global and Planetary Change

1. K. Eiane
2. M. Ohman
3. J. Runge
4. E. Durbin
5. H. Hirche
6. B. Niehoff
7. C. Johnson
8. P. Pepin

In Oceanography

1. K. Eiane
2. M. Ohman
3. E. Durbin
4. J. Runge
5. H. Hirche
6. M. Heath
7. B. Niehoff
8. P. Pepin

Citations in the corpus

• The North Atlantic Ocean as habitat for Calanus finmarchicus: Environmental factors and life history traits (2014, background): “…of C. finmarchicus is mainly governed by temperature, food availability and/or con-specific abundance, which results in marked seasonal and regional differences in stage-specific mortality patterns (Ohman and Hirche, 2001; Ohman et al., 2002, 2004; Heath et al., 2008; Plourde et al., 2009b).”
• A comparative study of Calanus finmarchicus mortality patterns at five localities in the North Atlantic (2004, methodology): “yModified Vertical Life Table method (Ohman et al., 2002).”
• Stage-specific mortality of Calanus finmarchicus, Pseudocalanus elongatus and Oithona similis on Fladen Ground, North Sea, during a spring bloom (2004, background): “The retentive circulation in both Dabob Bay and Georges Bank may serve to concentrate predators on mid-life-history stages of Pseudocalanus spp. at more elevated abundances than in the North Sea.”
• Interannual variation in phytoplankton blooms and zooplankton productivity and abundance in the Gulf of Maine during Winter (2003, unknown): “Mortality rates for a combined egg-through-N2 stage were made using a modified version of the VLT method that incorporates estimates of daily EP into the water column by C. finmarchicus (see Ohman et al. 2002).”
• Flexible diel vertical migration behaviour of zooplankton in the Irish Sea (2004, background): “However, nauplii and early copepodite stages are usually the main food source of fish larvae (e.g. Conway 1980, Conway et al. 1998); they also suffer from invertebrate predation, and they often have higher mortality rates than adults (Ohman et al. 2002).”