FISHERY BULLETIN: VOL. 72. NO. 3 



tags. This marking system made it possible to 

 sample any point on the transect and return to the 

 same position even during days of marginal 

 underwater visibility. 



The entire transect area was stratified into six 

 2 X 50 m areas. Two sample points were randomly 

 selected per stratum; at each of these 12 locations 

 a 4-m2 quadrat was placed in September 1968. 

 Each quadrat consisted of polypropylene line, 

 arranged in a square 2 m on a side, and held in 

 place at each corner with galvanized spikes. Two 

 additional 4-m2 quadrats (no. 13 and 14) were 

 added in August 1969, but in this case the loca- 

 tions were selected by the presence of juvenile 

 Macrocystis in this part of the kelp bed. The latter 

 two quadrats were not included in the evaluation 

 of density or aggregation. 



During September 1968 a drawing or map of 

 each fixed quadrat was made underwater on a 

 sheet of plastic recording natural history infor- 

 mation and the position of each individual macro- 

 organism. A brass meter square quadrat divided 

 into 0.25-m2 sections was used while mapping 

 the quadrats in order to reduce the visual area 

 being examined. Quadrats were examined at 

 irregular intervals (i.e. monthly, bimonthly, or 

 quarterly) by the same observer. 



Data regarding density, frequency of occur- 

 rence, and distribution patterns were calculated 

 from observations in the 12 4-m^ fixed quadrats 

 and from 48 1-m^ quadrats placed at randomly 

 chosen points along the transects. All quadrat 

 analyses are from observations taken in August 

 1972. The distribution patterns of the conspicuous 

 species were analyzed with the index of disper- 

 sion, variance/mean x (number of observations 

 -1), described by Greig-Smith (1964). If the var- 

 iance to mean ratio is significantly less than 1.0, 

 the distribution is considered even, while an 

 index significantly greater than 1.0 indicates an 

 aggregated pattern of distribution. Significance 

 is tested in a Chi square table with n - \ degrees 

 of freedom. Lack of significance indicates a ran- 

 dom distribution. Since the results of most such 

 indices depend upon quadrat size, we compared 

 independently the A-xn^ quadrats and the l-m^ 

 quadrats. The only differences in the two analyses 

 of pattern were minor and involved slight loss 

 of significance in three of the 4-m^ quadrat 

 analyses; in each case this was a result of small 

 numbers of individuals in the 12 larger samples. 

 The results of the pattern analysis are given in 

 Table 5 and are based on the 48 l-m^ quadrats. 



THE ALGAL ASSOCIATION 



The floristic components of southern California 

 kelp beds have been described by Limbaugh 

 (1955); Dawson, Neushul, and Wildman (1960); 

 North (1971); and Neushul (1971). Many of the 

 mainland and insular kelp stands that we have 

 surveyed in southern California appeared dis- 

 similar with respect to the algal species present 

 or their relative abundances. Therefore a gen- 

 eralized list of the algae known to inhabit these 

 kelp communities is inadequate when describing 

 a particular stand or comparing two or more 

 kelp stands (Dawson, Neushul, and Wildman, 

 1960). The one characteristic of all mainland 

 southern California beds appear to share is the 

 overall domination of Macrocystis, in terms of 

 both biomass (McFarland and Prescott, 1959) 

 and apparent competition for the available light. 

 The kelp bed at Del Mar is two layered, with the 

 floating portion o{ Macrocystis suspended over an 

 algal turf composed primarily of encrusting coral- 

 lines. There is also a thinly scattered under- 

 growth of Pterygophora californica, Laminaria 

 farlowi, and Rhody me nia pad fica. These species 

 are taller than the corallines, but they occur so 

 sparsely in this area that they cannot be con- 

 sidered a separate canopy. The algal association 

 at Del Mar consisted of only a few species of 

 attached macroalgae (Table 1); most of these 

 plants were found along the margins of the 

 Macrocystis bed. 



Table 1. — The attached macroalgae found in the Del Mar 



kelp bed. 



Bossiella orbigniana (Decaisne) Silva 



Corallina officinalis var. cfiilensis (Harvey) Kutzing 



Cystoseira osmundacea (Turner) C. Agardh 



Desmarestia munda Setchell and Gardner 



Desmarestia tabacoides Okamura 



Laminaria farlowii Setchell 



Litfiopliyllum sp. 



Litfiothamnium sp. 



fi/lacrocystis pyrifera (Linnaeus) C. Agardh 



Pterygophora californica Ruprecht 



Rhodymenia arborescens Dawson 



Rhodymenia pacifica Kylln 



Tiffaniella snyderae Farlow 



OBSERVATIONS ON 

 MACROCYSTIS PYRIFERA 



The giant kelp was the most abundant and 

 conspicuous species of brown algae within the 

 study area. It is perennial and usually grows 

 attached to solid substratum anchored into place 



672 



