Growth and sexual maturity were compared among Monterey Botryllus schlosseri colonies cultured in the laboratory and in Monterey Marina in two separate studies: Phase I—April to July 1984, a time when Botryllus growth is rapid in the field, and Phase II—December 1984 to March 1985, a time when growth is minimal in the field. Laboratory colonies were kept in tanks of standing, aerated filtered seawater at 15° C, 20° C, and 24° C; the seawater was changed daily or on alternate days. Food types were two concentrations of an algal mixture and five concentrations of Liquifry, a commercially available food for filter-feeding marine invertebrates. All algae-fed colonies did poorly. During Phase I, the colonies kept in Monterey Marina grew much faster than those in the laboratory, but they took longer to reach sexual maturity than the Liquifry-fed colonies grown at 20° C and had a lower survivorship. In Phase II, Botryllus growth rates and survivorships in seven of the eight laboratory treatments were better than those of marina colonies. These laboratory treatments yielded a substantial proportion of sexually mature colonies, whereas none of the marina colonies produced eggs during Phase II.
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Boyd et al. (1986) studied this question.