Inter-and intralocular distribution of yucca moth larvae in Yucca whipplei (Agavaceae)

ThQ mollusk assemblage associated with giant kelp {Macrocystis pyrifera) fronds off Santa Catalina Island, California was examined monthly from June 1975 through December 1976.Mollusks comprised 1.0, 1.6, and 2.9% (by number) of all invertebrates associated with kelp fronds in the canopy, middle, and bottom zones of the kelp forest, respectively.Forty one species (36 gastropods, 5 bivalves) were collected, ranging from 14-28 for any given month.The mean number of species present was greater in the bottom (16.9) and middle zones (15.6) than in the canopy (9.3).Most species (29) were rare in occurrence (<1/ kg kelp) and small (<4 mm) in size.Throughout the study, more mollusks were found in the bottom zone than in the middle; fewest numbers were present in the canopy.Most species reflected this general pattern; only the nudibranch Polycera tricolor was more abundant in the canopy than in the lower zones.As a group, mollusks were most abundant on Macrocystis fronds during summer-fall.Mollusks are an important group of invertebrates within giant kelp forests {Macrocystis pyrifera) along the coast of California.Several species are herbivores and utilize the kelp as food (Jones 1971; Leighton, 1971; Rosenthal et al. 1974), whereas others serve as a food resource for invertebrates and fishes residing within the kelp forests (Quast 1968; Feder et al. 1974; Hobson and Chess 1976;Schmitt 1982; Schmitt etal.1983