ABSTRACT: Snails Littorina littorea with and without artificial epibionts were exposed in situ for nearly 1 mo. Measurement of individual shell length increase over this period revealed that clean snails grew 3 times faster than fouled snails. These results compare well with previously conducted flume experiments (Wahl 1996). This epibiosis effect is thought to be due to increased drag--the only feature distinguishing the 2 treatment groups--caused by the presence of epibionts on the shell. Increased drag probably entails higher energy expenditure for pedal activities (attachment and locomotion) and a reduced allocation of resources towards growth and, possibly, reproduction.

KEY WORDS: Littorina littorea · Drag · Simulated epibiosis · Growth rates · In situ experiments · Energetic trade-offs

Published in MEPS Vol. 151 (1997) on May 22
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1997