File:Bulletin (1971-) (20429175531).jpg

Title: Bulletin
Identifier: bulletin7073sout (find matches)
Year: 1971- (1970s)
Authors: Southern California Academy of Sciences
Subjects: Science; Natural history; Natural history
Publisher: Los Angeles, Calif. : The Academy
Contributing Library: New York Botanical Garden, LuEsther T. Mertz Library
Digitizing Sponsor: The LuEsther T Mertz Library, the New York Botanical Garden

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10 111 I II I IS SOI I III l<\ (II II OK\I I \CADEMYOl SOU \( I S VOLUME 70 species were then grouped according to the month in which the running means showed a maximum. The species in which the maximum running mean was not more than double the value of the minimum running mean were considered to have no maxi- mum. Then, the original weighted data, not the running means, of each species in each group were added together, and the result is shown in Figure 6. Ranking of stations.—The changes noted in the algal flora of the various stations between 1956-9 and 1968-70 are shown in Table II. These changes were ranked in order from greatest decrease to greatest increase. The ranks based on species number and average score showed the high rank correlation coefficient (Schefler, 1969: 133) of + 0.7, so a combined ranking was determined using the changes in both the species number and the average score, and is shown in Table II. The stations were also ranked according to the degree they are exposed to human use and collecting activity, to air pollution, and to marine pollution from sewage outfalls. These are the three factors quoted by Dawson (1965a: 174. 181) as prob- able causes of deterioration in the algal flora. The ranking according to human use was made after a consideration of the length of walk from the nearest roadhead by public access to the station, the amount of parking available in the vicinity of the roadhead, and the degree to which the area is built up. The factors considered in the ranking according to exposure to air pollution are shown in Figure 7. The number of days per year when the measured concentration of oxidant exceeded the state ambient air quality standard was used as a measure of air pollution. All the monitoring stations, how- ever, are far from the beach, so the ranking was derived from a consideration of the prevailing winds in the area, the distribution of high ground, and the pattern shown by the incidence of higher than standard levels of oxidant at the inland monitor stations. The information used for ranking the intertidal 300- 8 200- < 100- /,-
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