Life-history characteristics, population dynamics, secondary production and calcification were measured at a permanent site between June 1994 and June 1996. Secondary production and calcification were then extrapolated to the whole Bay. D. arietina has a 2 yr life cycle with worms first reproducing when they are 1 yr old.
Reproduction occurs during spring with several spawning peaks each year.
Development is planktotrophic and the duration of the pelagic phase is close to 6 wk. Recruitment does not correlate with larval supply due to high mortality rates during the first benthic stage. Mortality follows an exponential model. Growth is best described by a logistic model and is almost restricted to the first year of the life cycle. Density significantly decreased between 1996 and 1998.