Population dynamics of the barnacle <Emphasis Type="Italic">Chthamalus montagui</Emphasis> at two spatial and temporal scales in northern Spain |
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Authors: | Raquel Suárez Julio Arrontes |
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Institution: | (1) Departamento de Biología de Organismos y Sistemas, Universidad de Oviedo, 33071 Oviedo, Spain |
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Abstract: | This study describes spatial and temporal patterns of variability in population parameters in the barnacle Chthamalus montagui Southward in three localities of northern Spain and evaluates whether density-dependent settlement may regulate population
dynamics. The sampling design considered two spatial scales, localities and sites within localities, and two temporal scales,
years and six month intervals. Density, amount of free space, mortality, growth rate and magnitude of settlement (both absolute
and per unit of free space) were obtained from photographs of permanent quadrats and from direct counts in the field. The
number of settlers in scraped and untouched quadrats was used to estimate the importance of the presence of conspecifics in
settlement. Significant variation at the two spatial and temporal scales was found for most parameters. Large spatial and
temporal variations in adult mortality rate, density, and settlement were observed. Patterns of mortality were not consistent
with differences in density among localities. Differences in settlement among localities were maintained through time. We
suggest that magnitude of settlement is regulated by persistent features such as topography or local water circulation. We
assume that early post-settlement mortality does not differ among localities. In the absence of differential mortality, settlement
determines average population density within localities. Within localities, settlement was independent of density and free
space. No consistent evidence was found on preferential settlement at the vicinity of conspecifics. The main conclusion is
that density-dependent settlement is not relevant for the regulation of the populations of C. montagui in the northern Spain. Regulation might occur by density-dependent processes within the adult fraction of the population
and/or the larval phase before settlement. |
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