Functional Roles of Schizoporella and Styela in the Fouling Community at Beaufort, North Carolina

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Abstract
The functional roles of Schizoporella, an encrusting bryozoan, and Styela plicata, a solitary tunicate, were investigated by continuously removing each species from the developing community for 15 months. Observations were also made on the undisturbed community after the cessation of removals. Two experiments are reported here, initiated in October 1972 and 1973, respectively, and terminated in December 1976. When dense, Schizoporella excluded other species from the space it occupied, resulting in a patch with fewer species and with fewer changes in species composition through time. The maximum persistence time appeared to be °2 years and Schizoporella was unable to invade space occupied by other species. Styela also excluded other species from the community when dense, but its larvae were capable of invading space occupied by other species. The attachment sites of Styela on other organisms were often unable to support the large animals resulting from a summer of rapid growth. Thus, Styela often sloughed off in the fall, (even though the individuals may have been healthy) taking other organisms with it. In a short time frame, Styela stabilized the community, resisting invasion as did Schizoporella, but destabilized the community on a different time scale because of the approximately annual slough—offs.