Interactions between an ascogiossan sea slug and its green algal host: branch loss and role of epiphytes

摘要: On rocky lntert~dal shores in Oregon USA the ascoglossan (= sacoglossan) sea slug Plaada dendnhca A & H consumed green seaweed Cod~um fragile (Sur ) Har but not eplphytic red alga Ceram~um cod~cola J Ag attached to C frag~le F~eld s tud~es conducted from 1986 1992 suggested that herb~vore grazing negatively affected Dunng spnng and summer P attacked ca 70 % of large fraglle (thall~ > l0 cm) at Boller Bay, Ascoglossans were most abundant on axillary region branches Grazing by he1 b~vore weakened branches, resulting In branch loss thall~ w ~ t h epiphyte more frequently than those w~thout ep~phytes a 1 mo f~eld expenment dendnt~ca settlement survivorsh~p greater thalh wlth thalli epiphytes expenmentally chpped Recently settled recruts associated with ep~phyte cover did larger ascoglossans The slug-seaweed-ep~phyte associahon represents an unusual form herbivore-plant mteract~on (1) herbivores do consume (2) enhance herbivore attack