Seasonal Changes in Size Structure of Sargassum and Turbinaria Populations (phaeophyceae) on Tropical Reef Flats in the Southern Red Sea
type: Dataset
description: Seasonal variation in density, thallus length and biomass, population size structure, and allometric length-biomass relationships was investigated in populations of Sargassum ilicifolium (Turner) C. Agardh, Sargassum subrepandum (Forssk.) C. Agardh, and Turbinaria triquetra (J. Agardh) Kütz. (Phaeophyceae) on shallow reef flats in the southern Red Sea. Thallus length and biomass varied strongly with season, with the highest values occurring in the cooler months. Thallus densities showed no significant temporal variation. Log-total biomass versus log-density relationships were positive throughout the growth season without any decrease in the slope of the relationship. In two populations, biomass-density combinations approached the interspecific biomass-density line, but the massive annual shedding of modules occurred before self-thinning would set in. Allometric length-biomass relationships varied with season in all populations and were associated with seasonal module initiation, growth, and shedding. Evidence of a strong asymmetric competition was found in two high-density populations. These populations showed a predominance of small thalli during peak development, asymmetrical Lorenz curves, increasing Gini coefficients, and increasing thallus length relative to biomass during the main growth phase. In two other less crowded populations, small thalli were absent during peak development, Lorenz curves were symmetrical, and Gini coefficients decreased during the main growth phase. In these populations, size equalization appears to be due to responses at the modular level rather than size-dependent mortality. We conclude that changes in size structure in this highly seasonal environment are determined by module dynamics, modified by asymmetric competition in some populations, with a minor role of recruitment and no regulatory effect of self-thinning.
issued: 2026-05-09T20:57:07.203211
language: en
modified: 2026-05-09T20:57:07.203217
contact point: Organization
  fn: CCSD
keyword: allometry
keyword: asymmetric-competition
keyword: biomass
keyword: density
keyword: infoeu-reposemanticsarticle
keyword: journal-articles
keyword: sdebeenvironmental-sciencesbiodiversity-and-ecology
keyword: self-thinning
keyword: size-hierarchies
keyword: size-inequality
landing page: 0022-3646

Seasonal Changes in Size Structure of Sargassum and Turbinaria Populations (phaeophyceae) on Tropical Reef Flats in the Southern Red Sea
type: Distribution
format: HTML
issued: 2026-05-09T20:57:07.216726
modified: 2026-05-09T20:57:07.185635
access URL: https://hal.science/hal-00858460

test_moissonnage_selune
type: Agent