Hopkins Marine Station Student Paper

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(full paper is archived in the Miller Library)

Title: The symbiotic relationship between Notoacmaea plaeacea and Phyllospadix torreyi: distribution by exposure and feeding behavior
Student Author(s): Gansel, John A.
Faculty Advisor(s): Baxter, Chuck
Pages: 17
Location: Final Papers Biology 175H
Date: June 1980
Keywords: symbiosis at the seashore
Abstract: 1. Distribution studies indicate that differences in Notoacmaea paleacea population body sizes correspond to factors of wave intensity and desiccation from exposure to air. 2. The mean grazing rate on Phyllospadix torreyi is 38.63 mm of blade length per day or approximately 220mm over an average grazing residency of 5.67 days. N. paleacea consumes about 1.7 mg per day dry weight of P. torreyi. 3. Grazing results in over a 30% loss in photosynthetic capacity. 4. Gut analysis shows P. torreyi epidermal cells constitue about 85% of the diet of N. paleacea with small amounts of xylem cells and diatoms aking up the remainder. 5. Periods of residency of individual limpets on blades of Phyllospadix torreyi may be grouped into two categories: full residency periods of 5.76 days and abbreviated residency periods of one observation. 6. Full residency periods indicate grazing behavior while abbreviated residency periods indicate rejection of the blade as a food source. This points to the existence of a mechanism that enables N. paleacea to detect previous residency. This mechaim controls overgrazing, a control that is critical to the success of P. torreyi and N. paleacea.