Reprint Series No. 29

A STUDY OF PHYLLAPLYSIA TAYLORI IN THE EELGRASS ECOSYSTEM OF PADILLA BAY Amy DeLorenzo   May 1999
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Bibliographic Citation
DeLorenzo, Amy. 1999. A study of Phyllaplysia taylori in the eelgrass ecosystem of Padilla Bay. Master of Science thesis. Western Washington University, Bellingham, Washington. 88 pp. Washington State Department of Ecology (Publication No. 00-06-007), Padilla Bay National Estuarine Research Reserve Reprint Series No. 29.

Abstract
In eelgrass systems, the interactions and relationships among Zostera marina, the epiphytes, and the macrofaunal grazers are important to the dynamics of the system. Zostera benefits from the presence of grazers which consume the epiphytic growth fouling the blades of Zostera. Phyllaplysia taylori, an opisthobranch mollusc, is one species of grazer in the eelgrass ecosystem of Padilla Bay. This research, consisting of a lab study and a field study, focused on the distribution patterns of P. taylori and its abundance within the eelgrass system of Padilla Bay.

The lab study assessed how the behavior of P. taylori affects its distribution. The response of P. taylori to two characteristics of substrate, orientation and color, was tested. P. taylori demonstrated a significant orientation preference and a significant color preference. The field study evaluated how specific factors affect the densities of P. taylori in its natural environment. Three sites (March Point, Kirby Beach, and Bayview) were sampled and compared with respect to epiphytic and macrofaunal communities on eelgrass. P. taylori was found abundantly at March Point, moderately at Bayview, and negligibly at Kirby Beach. Kirby Beach and Bayview were most similar with respect to epiphytic communities. March Point and Kirby Beach had more similar macrofaunal communities. The distribution and abundance of P. taylori is sensitive to a number of environmental factors, epiphytic and macrofaunal communities representing only two possibilities. No striking trends were apparent when considering the relationship between P. taylori and these two factors. Therefore, more extensive research is necessary to determine what factors affect the population size of P. taylori within Padilla Bay.