(full paper is archived in the Miller Library)
Title: Species groupings in California intertidal sponges and ascidians
Student Author(s): Benn, Paul
Faculty Advisor(s): Wagenbach, Gary
Location: Research Reports Carleton College Biology 212
Date: 1976 1976
Abstract: Intertidal sponges and ascidians provide convenient animals to study species groupings with because of their lack of behavior and movement. Mathematical analysis of co-occurrences in 250 sites on the intertidal rocks found distinct groupings, but the groupings differed depending on what analytical method was used. Indices used for linking species into groups were Pielou's X2,X2 corrected, H, and H', and Fager's t and Ij. Analysis using Ij values gave the clearest goups. The mathematically significant groups are cleaarly visible in the field. Differences between groups in terms of water pH, water silicate content, and oxygen consumption are examined, and the possible secretion, by Ophlitaspongia pennata, of a chemical inhibitory to sponge and ascidian larvae of types not in its groups is under investigation.