The effects of shore level on the epifauna communities associated with Fucus serratus (L.) in the Menai Strait, North Wales
Wood, V.; Seed, R. (1980). The effects of shore level on the epifauna communities associated with Fucus serratus (L.) in the Menai Strait, North Wales. Cah. Biol. Mar. 21(2): 135-154
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723; e-ISSN 2262-3094, meer
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| Abstract |
Fucus plants became progressively smaller and less abundant with increasing intertidal height although prolonged exposure to strong tidal currents adversely affected plants at the lowest shore levels. Of the 19 sessile taxa present on F. serratus only the five most abundant species were considered in detail: the bryozoans Flustrellidra hispida, Electra pilosa and Alcyonidium hirsutum and the hydroids Dynamena pumila and Campanularia flexuosa. The establishment and abundance of these epifaunal species decreased markedly at the higher shore levels. One or more of the following mechanisms promote ecological isolation _ choice of plant, zonation of species along individual fronds, preference for concave or convex surfaces and colony growth orientated towards the younger, less encrusted distal regions of the plants. Where these mechanisms fail, competition for space can be severe, particularly in the most favourable parts of low shore plants. A competitive hierarchy through the sequence Flustrellidra-Alcyonidium-Electra-Dynamena was clearly evident. The larvae of Alcyonidium settled in abundance between October and January and exhibited a clear preference for concave surfaces of distal fronds at all shore levels. The stem height of Dynamena varied with respect to shore level and position along the plant. This investigation strongly suggests that the major epifaunal species of F. serratus are unable to take full advantage of the additional space provided by the unusually extended zone of this alga in this particular geographical locality. |
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