Hopkins Marine Station Student Paper

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Title: A quantitative analysis of human activity at Point Pinos rocky intertidal
Student Author(s): Clowes, Sarah W.
Coleman, Bronwen S.
Faculty Advisor(s): Watanabe, James
Pages: 47
Location: Final Papers Biology 175H
Date: June 2000
Abstract: Human activity at Point Pinos, a popular rocky intertidal site in Pacific Grove, CA, was quantified over a period of seven weeks from April 6, 2000 to May 28, 2000. Over 17,000 people were observed over the 7 weeks. Intensity of activity varied greatly among 9 contiguous sites within Pt. Pinos, ranging from 12 to 36 people ha-1 sweep-1 (averaged over the 7 weeks for each site). There was also a high degree of day-to-day variation with daily values ranging from <20 to nearly 700 per sweep, pooled over the entire Point. Of all visitors, only 18% ever entered the rocky intertidal zone itself, with >80% remaining in the parking lots or on the sandy beach areas. Data indicated that collecting, or taking of shells or invertebrates, occurred rarely. Trampling appeared to be the greatest potential impact on sessile species located in the high and mid intertidal zones. A comparison of the abundance of potentially susceptible (i.e. Pelvetia compressa) and non-susceptible (i.e. limpets) sessile species between high-use and low-use Sites indicated that bare space increases at the high-use Sites. The abundance of non-susceptible species did not differ significantly between Sites, whereas the abundance of susceptible species decreased in the high-use Sites. Significant spatial variability between Sites revealed that differences in species abundance between high-use and low-use Sites cannot solely be attributed to trampling; hence, other factors such as sand scour and wave action may have contributed to the heterogeneity.