Hopkins Marine Station Student Paper

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(full paper is archived in the Miller Library)

Title: Long term changes in the Endocladia-Balanus community at Hopkins Marine Station, Pacific Grove, California
Student Author(s): Simons, Ashley
Leydig, Erin
Faculty Advisor(s): Watanabe, James
Pages: 24
Location: Final Papers Biology 175H
Date: June 1996
Abstract: The red alga, Endocladia muricata, and the barnacle, Balanus glandula, form a widespresad association in the rocky intertidal along the Pacific coast of North American (Glynn 1965). One portion of that zone, at Hopkins Marine Station, Pacific Grove, California, was examined to determine its vertical height and species composition. These measurements were then compared with data from Glynn (1965). The current upper and lower limits of E. muricata are an average of 1.20 and 1.05 feet lower respectively than they were in 1965. At three of Glynn's study sites, replicate 5x5 cm quadrats were sampled in the middle of the current Endocladia zone, taking care to duplicate as many of Glynn's original quadrate characteristics as possible. Analysis of algal biomass showed no significant change in the abundance of E. muricata in these areas. The species composition of the assemblage has changed little, but there has been a significant change in the relative abundances of species. Abundance of the bivalve, Musculus sp., has increased significantly, while that of the barnacle, B. glandula, has decreased. These finding indicate that much of the E. muricata animal community has moved downward along with the algal cover, but that the abundance of a few predominate species within this community has changed. These data provide a base for future quantitative studies of temporal change in the E. muricata zone and may aid in evaluating the effects of environmental change on intertidal habitats.