Understanding demography in an advective environment: modelling Calanus finmarchicus in the Norwegian Sea

D C Speirs, W S C Gurney, S J Holmes, M R Heath, S N Wood, E D Clarke, I H Harms, H J Hirche, E McKenzie

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

1. Attempts to understand the demography of natural populations from time-series can be hampered by the fact that changes due to births and deaths may be confounded with those due to movement in and out of the sampling area. 2. We illustrate the problem using a stage-structured time-series of the marine copepod Calanus finmarchicus sampled in the vicinity of a fixed location but where the demography is shown to be inconsistent with the assumption of a closed population. 3. By combining a realistic simulation of the hydrodynamic environment with a model of phenology we infer the time and location at which the stages observed in each sample were recruited as eggs. This yields a spatial and temporal map of the recruitment history required to produce the observed densities. 4. Using an empirical relationship between C. finmarchicus egg production and the abundance of phytoplanktonic food, the spatio-temporal patterns in chlorophyll a can be inferred. The distributions during the spring bloom are spatially heterogeneous, and we estimate that the phytoplankton patches are of the order of 30 km across. This result is robust to substantial variations in the assumed stage-dependent mortalities. 5. We conclude that information on advective transport can be used to make testable predictions about the scale of spatial heterogeneities. These, in turn, imply the appropriate spatial scale over which time-series might be replicated in order to obtain more information about unknown processes such as mortality
Original languageEnglish
Pages (from-to)897--910
Number of pages14
JournalJournal of Animal Ecology
Volume73
Publication statusPublished - Sep 2004

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Calanus finmarchicus
demography
time series analysis
time series
modeling
mortality
egg production
phenology
hydrodynamics
chlorophyll a
Copepoda
algal bloom
advection
phytoplankton
egg
death
chlorophyll
sampling
history
prediction

Cite this

Speirs, D. C., Gurney, W. S. C., Holmes, S. J., Heath, M. R., Wood, S. N., Clarke, E. D., ... McKenzie, E. (2004). Understanding demography in an advective environment: modelling Calanus finmarchicus in the Norwegian Sea. Journal of Animal Ecology, 73, 897--910.

Understanding demography in an advective environment: modelling Calanus finmarchicus in the Norwegian Sea. / Speirs, D C; Gurney, W S C; Holmes, S J; Heath, M R; Wood, S N; Clarke, E D; Harms, I H; Hirche, H J; McKenzie, E.

In: Journal of Animal Ecology, Vol. 73, 09.2004, p. 897--910.

Research output: Contribution to journalArticle

Speirs, DC, Gurney, WSC, Holmes, SJ, Heath, MR, Wood, SN, Clarke, ED, Harms, IH, Hirche, HJ & McKenzie, E 2004, 'Understanding demography in an advective environment: modelling Calanus finmarchicus in the Norwegian Sea', Journal of Animal Ecology, vol. 73, pp. 897--910.
Speirs DC, Gurney WSC, Holmes SJ, Heath MR, Wood SN, Clarke ED et al. Understanding demography in an advective environment: modelling Calanus finmarchicus in the Norwegian Sea. Journal of Animal Ecology. 2004 Sep;73:897--910.
Speirs, D C ; Gurney, W S C ; Holmes, S J ; Heath, M R ; Wood, S N ; Clarke, E D ; Harms, I H ; Hirche, H J ; McKenzie, E. / Understanding demography in an advective environment: modelling Calanus finmarchicus in the Norwegian Sea. In: Journal of Animal Ecology. 2004 ; Vol. 73. pp. 897--910.
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AB - 1. Attempts to understand the demography of natural populations from time-series can be hampered by the fact that changes due to births and deaths may be confounded with those due to movement in and out of the sampling area. 2. We illustrate the problem using a stage-structured time-series of the marine copepod Calanus finmarchicus sampled in the vicinity of a fixed location but where the demography is shown to be inconsistent with the assumption of a closed population. 3. By combining a realistic simulation of the hydrodynamic environment with a model of phenology we infer the time and location at which the stages observed in each sample were recruited as eggs. This yields a spatial and temporal map of the recruitment history required to produce the observed densities. 4. Using an empirical relationship between C. finmarchicus egg production and the abundance of phytoplanktonic food, the spatio-temporal patterns in chlorophyll a can be inferred. The distributions during the spring bloom are spatially heterogeneous, and we estimate that the phytoplankton patches are of the order of 30 km across. This result is robust to substantial variations in the assumed stage-dependent mortalities. 5. We conclude that information on advective transport can be used to make testable predictions about the scale of spatial heterogeneities. These, in turn, imply the appropriate spatial scale over which time-series might be replicated in order to obtain more information about unknown processes such as mortality

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