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Size structure and inequality in a commercial stand of the seaweed gelidium-sesquipedale

dc.contributor.authorSantos, R
dc.date.accessioned2018-12-07T14:53:47Z
dc.date.available2018-12-07T14:53:47Z
dc.date.issued1995-03
dc.description.abstractThe temporal dynamics of the frequency distributions of 2 measures of Gelidium sesquipedale frond size, length and weight, was investigated in a subtidal stand under commercial exploitation. Frond weight/length allometry was highly variable, both seasonally and between years, showing that in this species weight and length cannot be used interchangeably as a measure of frond size. Physical disturbances played a fundamental role in allometric variability. The loss of branches due to commercial harvest and storms reduced the slope of the log weight/log length relationship. During spring the slope increased, indicating the production and growth of lateral branches. Size differences among individuals in the population (inequality) were quantified by 3 statistics: the skewness coefficient (g(1)), the coefficient of variation (CV), and the Gini coefficient (G). Highly significant changes in frond length inequality, but not weight, were shown. These correspond to periods when G. sesquipedale length structure varied due to the combined effects of the demographic parameters that regulate the population (frond recruitment, survival, breakage and growth). Graphical analysis of significantly different length structures revealed that a recruitment peak of vegetatively developed fronds occurred during winter, following periods of high frond mortality and breakage caused by both human (summer harvesting) and natural (late fall storms) disturbances. During late spring and summer, the density of smaller fronds decreased due to mortality and growth into higher size classes. To assess density-dependent regulation processes, such as suppressed growth of smaller fronds and self-thinning, the time variation of both relationships, inequality/mean frond weight and biomass/density, was analysed. Inequality/mean frond weight and biomass/density values decreased from summer to winter and increased to the following summer. The increase of inequality while mean frond weight is increasing is consistent with the asymmetric competition theory on the development of crowded plant stands, and supports the hypothesis that the slower growth of smaller fronds during this period (Santos 1994; Mar. Ecol. Prog. Ser. 107: 295-305) is due to intraspecific competition. The time trajectory of the biomass/density relationship is perpendicular to and lies above the theoretical self-thinning line. Evidence for self-thinning was thus not detected. A conceptual model for the functioning of this population is proposed. Thinning and frond breakage caused by disturbances might be keeping intraspecific competition in these G. sesquipedale crowded stands (up to 18 000 fronds m(-2)) at low levels.
dc.description.versioninfo:eu-repo/semantics/publishedVersion
dc.identifier.doi10.3354/meps119253
dc.identifier.issn0171-8630
dc.identifier.urihttp://hdl.handle.net/10400.1/11684
dc.language.isoeng
dc.peerreviewedyes
dc.publisherInter-Research
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/
dc.subjectSelf-thinning rule
dc.subjectPlant-populations
dc.subjectPower law
dc.subjectDensity
dc.subjectGrowth
dc.subjectCompetition
dc.subjectRhodophyta
dc.subjectDistributions
dc.subjectVariability
dc.subjectSuppression
dc.titleSize structure and inequality in a commercial stand of the seaweed gelidium-sesquipedale
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage263
oaire.citation.issue01-mar
oaire.citation.startPage253
oaire.citation.titleMarine Ecology Progress Series
oaire.citation.volume119
person.familyNameSantos
person.givenNameRui
person.identifier42560
person.identifier.ciencia-id9B18-444D-2244
person.identifier.orcid0000-0002-7861-4366
person.identifier.ridB-4168-2008
person.identifier.scopus-author-id7201375018
rcaap.rightsopenAccess
rcaap.typearticle
relation.isAuthorOfPublication84487ca8-404a-4584-81f0-3662c340d712
relation.isAuthorOfPublication.latestForDiscovery84487ca8-404a-4584-81f0-3662c340d712

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