16 U.S. NATIONAL MUSEUM BULLETIN 2 58 



generally 4 to 10 species of Amphipoda occur, with domination by 

 Hyale rubra jrequens, often with numerous individuals of Amphilochus 

 litoralis and occasional unique locality occurrences of ampithoids 

 such as Ampithoe ftea and A. fmea. 



In the kelp-holdfast microcosm numerous secondary ecological 

 mechanisms must be operating besides the basic protection afforded 

 by the rhizomal interstices. The primary nestling and tube-dwelling 

 niches are rather consistently occupied by Hyale rubra jrequens and 

 Aoroides columbiae, but various species occupying secondary positions 

 as dominants are less consistently present. Presumably, the exposure 

 of the plants to surf, the accumulation of sediments, and the pres- 

 ence of epiphytes are a few of the inter-rhizomal factors associated 

 with the occurrence of amphipods. In 10 sets of samples of intertidal 

 holdfasts of Macrocystis, Egregia, and Laminaria collected throughout 

 the coastal area, Hyale rubra jrequens numerically dominated 6 times 

 and Aoroides columbiae was an abundant secondary dominant in 7 

 of the sample sets. Twenty-one other species were abundant secondary 

 dominants in the 10 sets of samples but only Parapleustes pugettensis 

 and Eurystheus thompsoni occurred in 4 sets, only Ericthonius bra- 

 siliensis, Elasmopus rapax mutatus, and Photis conchicola occurred in 

 3 sets, only Elasmopus holgurus, Oligochinus lighti, and Najna fcon- 

 siliorum occurred in 2 sets. The remaining 13 species occurred only in 

 one set apiece; among these species were such important inhabitants 

 of the Phyllospadix-pelvetiid zone as Elasmopus rapax serricatus, 

 Photis brevipes, P. elephantis, Megamphopus martesia, and Microjassa 

 litotes. 



Holdfasts of Macrocystis in depths below intertidal surf action 

 are very large (often with volumes of more than 100 liters). These 

 infrequently sampled habitats harbor a very diversified host of 

 amphipods, many of which are rare or absent in the intertidal zone 

 (sample 41 of Goleta, Appendix I). The dominant Amphipoda in 

 sample 41 are Photis bifurcata, P. brevipes, Mierodeutopus schmitti, 

 Maera simile, Eurystheus thompsoni, and Heterophlias seclusus esca- 

 brosa. More than 35 species have been found in one small aliquot of 

 the 40-liter sample and undoubtedly analyses of additional materials 

 would reveal numerous other species. In another Macrocystis holdfast 

 collected at Campbell station 6 near Goleta, the dominant Amphipoda 

 are Ceradocus spinicauda, Cymadusa uncinata, Maera simile, Miero- 

 deutopus schmitti, and Eurystheus mamolus. Few of those species 

 occur in the intertidal zone. Apparently Heterophlias of the Phliantidae 

 is a woody plant borer or scavenger, because, with one exception 

 noted below, its individuals have been collected in association with 

 kelps and they bear lignin-like material in their alimentary tracts. 

 Cymadusa uncinata, reaching 40 mm. in length, is the largest species 



