Propagule production and competition in species of Fucus

Bray, Alison M (1983) Propagule production and competition in species of Fucus. MSc(R) thesis, University of Glasgow.

Abstract

Several aspects of the ecology of Fucus propagules were studied. To establish the order of magnitude of propagule production in Fucus the rate of egg release for F. serratus was estimated in the laboratory, where it was found that the rate of release varied considerably between receptacles, but that there was a general trend to increased release during the second twenty-four hours in culture. This appeared to be associated with the trauma of introducing the plants to laboratory conditions. The rate of release appeared to be unaffected by different periods of exposure to air. It was estimated from the data that a fertile F. serratus plant may release fifty million eggs during a reproductive season and it was suggested that the eggs were released in a steady flow. Little information was collected on the dispersal pattern of Fucus propagules once, released. This was investigated on the shore for F. spiralis but was relatively unsuccessful, however, it was found that propagules preferentially settled in the minute depressions on the test substrata. This may be significant in providing the developing germling with protection from desiccation and grazers. The density of propagule settlement was found to significantly affect the length, mean dry weight per plant and mean volume per plant of F. serratus, F. vesiculosus and F. spiralis germlings. The effect of density on the yield of a germling lawn was also recorded. These results appear, to conform to the competition-density theory of higher plant studies A crowded stand of Fucua germlings was able to survive longer periods of aerial exposure in a tide-simulating apparatus than a sparse stand could. Crowding also appeared to have a very small protection effect against the grazer Littorina littorea, although crowding generally produced smaller individuals. It is concluded that it would be beneficial for an upper shore species to recruit in dense lawns so that the germlings are better protected from desiccation and for mid to lower shore species to recruit in sparse lawns where rapid growth is required to escape the size class vulnerable to grazers. However, there is little evidence to suggest that they actually do so.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Additional Information: Adviser: T A Norton
• Keywords: Botany
• Date of Award: 1983
• Depositing User: Enlighten Team
• Unique ID: glathesis:1983-73360
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 14 Jun 2019 08:56
• Last Modified: 14 Jun 2019 08:56
• URI: https://theses.gla.ac.uk/id/eprint/73360