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- Jenkins, S. R., et al.
(författare)
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Population dynamics of the intertidal barnacle Semibalanus balanoides at three European locations: spatial scales of variability
- 2001
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 217, s. 207-217
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Tidskriftsartikel (refereegranskat)abstract
- Spatial variability in the population dynamics of the intertidal acorn barnacle Semibalanus balanoides was investigated using a hierarchical sampling programme. Variability in a number of population parameters (size distribution, density, % cover, absolute growth and instantaneous mortality) was determined separately for new recruits and adults over 3 spatial scales. Three locations, SW Ireland, the Isle of Man and the west coast of Sweden, which cover a large part of the European range of this species, were selected to investigate variability over a large spatial scale (100s of kilometres). Two smaller scales, shore (1000s of metres) and site (10s of metres) nested within each location were also used. In addition, temporal variation over two 6 mo periods was also examined in the Isle of Man and Ireland. Most variability for all population parameters occurred over the largest spatial scale (location). This was a direct result of differences between Sweden and the other 2 locations, the Isle of Man and Ireland, which showed highly similar levels of all population parameters. The population of S, balanoides at the Swedish location was characterised by high growth rates, large size, high levels of mortality and a large turnover of bare space. At the spatial scale 'shore', only 1 population parameter, the growth rate of recruits, showed variability. At the smallest scale of 'site', all parameters showed significant variability except growth rate of adults. Calculation of variance components showed that differences between replicates (spatial scale: <0.5 m) accounted for little of the overall variability, in general less than the scales of site and shore. Examination of temporal variability over two 6 mo periods revealed no difference between time periods and no significant interaction between temporal and spatial scales, Thus, there was consistency of spatial variability over time. The potential causes of variability in population parameters of S, balanoides at different spatial scales and the implications for future studies are discussed.
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| 2. |
- Svensson, Carl Johan, 1976, et al.
(författare)
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Models of open populations with space-limited recruitment in stochastic environments: relative importance of recruitment and survival in populations of Semibalanus balanoides
- 2004
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Ingår i: Marine Ecology Progress Series. ; 275, s. 185-197
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Tidskriftsartikel (refereegranskat)abstract
- The relative importance of recruitment and post-recruitment processes in determining adult density among marine species varies considerably between species and populations. This study aimed to investigate the relative effects of variation in recruitment and survival rates on the density dynamics of 3 spatially separated natural populations of the barnacle Semibalanus balanoides (Isle of Man, SW Ireland and west Sweden). We analysed 2 different data-based stochastic matrix models of open populations with space-limited recruitment. Assumption testing supported the application of matrix-model theory for studying and comparing population variables of open populations. Recruitment was found to be partly dependent on free space, and mortality was size-specific and independent of other vital rates. Model simulations showed that the relative importance of recruitment and survival in shaping adult density depends on the existing variation of these vital rates at each location. In the Isle of Man the variation in density was primarily caused by variability in recruitment, while in SW Ireland the variability in survival induced the most variation. In west Sweden variation was high due to variability in both recruitment and survival. A life-cycle elasticity analysis across locations indicated that the population dynamics were generally more sensitive to changes in survival than to changes in recruitment. Also, locations with high variability in vital rates seemed better able to buffer sudden changes in vital rates. In addition, differences in survival and growth produced population structures that varied between populations. In the Isle of Man and west Sweden the populations consisted of mainly Size Category 1 individuals, while the population in SW Ireland had a linear relationship between size category and the proportion of individuals.
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