Marine Biology

, Volume 144, Issue 1, pp 61–70 | Cite as

Intraspecific competition in Fucus serratus and F. evanescens (Phaeophyceae: Fucales) germlings: effects of settlement density, nutrient concentration, and temperature

  • H. Steen
  • R. Scrosati
Research Article


Survival and growth of early post-settlement stages are critical for the development of seaweed populations. Fucoid germlings commonly settle in dense monospecific aggregates, where intraspecific competition and environmental variables (e.g. nutrient concentration and temperature) may affect survival and growth. Using factorial experiments, we determined the effects of settlement density (~10, ~50 and ~250 germlings cm−2), nutrient enrichment (from ~10 to ~40 µM N and from ~0.5 to ~2.5 µM P), and temperature (7°C and 17°C) on Fucus serratus and F. evanescens germlings in laboratory cultures over 3 months. Settlement density, nutrient concentration and temperature interactively affected growth of germlings, and the magnitude of this interaction varied between the two species. This represents the first record of such factorial interactions in Fucus spp. germlings. Intraspecific competition, estimated as the relative reduction in germling growth and survival from low to high densities, increased with decreasing nutrient concentration and increasing temperature in both species. While temperature and nutrient concentration had little effect on germling size distributions, size inequality and skewness generally increased with germling density, indicating that a few large individuals gained dominance and suppressed many smaller ones at high density. Self-thinning increased with settlement density and depended on nutrient concentration and species at high density. At high density, self-thinning increased with decreasing nutrient levels in F. evanescens, but not in F. serratus. At low density, nutrient enrichment increased germling growth in F. evanescens, but not in F. serratus, whereas growth in both species was stimulated by nutrient enrichment at higher densities. These results suggest that germling growth and self-thinning are more sensitive to variation in nutrient concentration in F. evanescens than in F. serratus. The potential implications of our findings for the understanding of eutrophication-related abundance changes in both species in southern Norway are discussed.


Nutrient Concentration Nutrient Enrichment Gini Coefficient Intraspecific Competition Settlement Density 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



We thank the staff at the Norwegian Institute for Water Research (NIVA), Marine Research Station at Solbergstrand, for supplying seawater and nutrients. Thanks to Prof. J. Rueness, Dr. S. Fredriksen, Dr. T. Andersen, and Dr. L. J. Naustvoll, for sharing their knowledge and making helpful comments on earlier versions of the manuscript. Finally, we thank Dr. S. Blank, for providing valuable technical assistance with the resampling software, and two anonymous referees, for reviewing and improving the quality of this paper. This study complied with environmental laws of Norway.


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Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  1. 1.Department of BiologyUniversity of OsloOsloNorway
  2. 2.Department of BotanyUniversity of British ColumbiaVancouverCanada

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