Marine Biology

, Volume 149, Issue 6, pp 1301–1311

Variability in grazer-mediated defensive responses of green and red macroalgae on the south coast of South Africa

  • Eliecer Díaz
  • Christine Güldenzoph
  • Markus Molis
  • Christopher McQuaid
  • Martin Wahl
Research Article

DOI: 10.1007/s00227-006-0320-6

Cite this article as:
Díaz, E., Güldenzoph, C., Molis, M. et al. Mar Biol (2006) 149: 1301. doi:10.1007/s00227-006-0320-6
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Abstract

Variabilities in the responses of several South African red and green macroalgae to direct grazing and the responses of one green alga to cues from grazers were tested. We used two feeding experiments: (1) testing the induced responses of three red and one green algae to direct grazing by mesograzers and (2) a multi-treatment experiment, in which the direct and indirect effects of one macrograzer species on the green alga Codium platylobium were assessed. Consumption rates were assessed in feeding assays with intact algal pieces and with agar pellets containing non-polar extracts of the test algae. Defensive responses were induced for intact pieces of Galaxaura diessingiana, but were not induced in pellets, suggesting either morphological defence or chemical defence using polar compounds other than polyphenols. In contrast, exposure to grazing stimulated consumption of Gracilaria capensis and Hypnea spicifera by another grazing species. In the multi-treatment experiment, waterborne cues from both grazing and non-grazing snails induced defensive algal traits in C. platylobium. We suggest that inducible defences among macroalgae are not restricted to brown algae, but that both the responses of algae to grazers and of grazers to the defences of macroalgae are intrinsically variable and complex.

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • Eliecer Díaz
    • 1
  • Christine Güldenzoph
    • 2
  • Markus Molis
    • 2
  • Christopher McQuaid
    • 1
  • Martin Wahl
    • 2
  1. 1.Department of Zoology and EntomologyRhodes UniversityGrahamstownSouth Africa
  2. 2.Leibniz Institute of Marine SciencesKielGermany