Nature of the distributional boundary of Fucus serratus on the north shore of Spain

The distribution of Fucus serratus has a sharp boundary In northern S p a n F serratus dominates the m ~d -~n t e r t ~d a l l e g ~o n west of Novellana, Asturias but is absent further east In a short t r a n s ~t ~o n zone F serratus 1s abundant within patches The causes underlying this pattern were investlgated by exper~rnental transplants of F serratus to locations In the transit~on zone and o u t s ~d e its normal range Plants moved outslde the normal range had slmllar growth and reproductive rates to those transplanted to the transition zone and ivith~n the zone of abundance F serratus recruited at s ~t e s outside the normal boundary apparently from transplanted thalli Temperature affected the growth rate of embryos of F serratus in laboratory exper~rnents Though high summer temperatures may be responsible for the lack of F serratus in the inner part of the Bay of Blscay temperature alone cannot explain the observed llm~t of distribution Other tactors such as l~mited dispersal ablllty and Interspecific compet~tion w ~t h other macroalgae might also be important In settlng the boundary for F serratus in northern Spain