Hopkins Marine Station Student Paper

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(full paper is archived in the Miller Library)

Title: The Relationship Between the Fractal Dimension of the Intertidal Alga Mastocarpus papillatus and the Abuncance of Grazing Snails
Student Author(s): Dau, Birgitt
Faculty Advisor(s): Denny, Mark
Pages: 16
Location: Final Papers Biology 175H
Date: June 1995
Abstract: Fractals describe the increase in length of a line with a decrease in the scale at which it is measured. A greater fractal dimension at a particular scale may translate into more habitat space for an animal of that size, and therefore greater expected abundances of that animal. I tested for the presence of such a relationship between the alga Mastocarpus papillatus and the small snails, Littorina scutulata and Tricolia pulloides, living on it. The use of M. papillatus provided a range of morphologies so that the effects of fractal dimension could be examined within a species of alga. This intra-species comparison allowed for a control of the grazing quality of the alga. Indeed higher fractal dimension was shown to correlate with a higher density of snails.
To determine if a fixed number of snails is associated with each thallus, experiments were performed in which the natural populations of snails on M. papillatus thalli were altered. The number of snails on each thallus was found to return to the original number of snails the day after treatment. This result indicates that there is a relationship between snail density and an individual alga.
Notes: Published in The Stanford Biologist, 1996 1:27-32