Hard-stemmed macrophyte stands,
which are less affected by crayfish (e.g. Nystr€om &
Strand, 1996), could act as a refuge for invertebrates such as snails, which are known to have behavioural escape responses in the presence of crayfish predator
(Nystr€om & Perez, 1998; Turner, Bernot & Boes, 2000).