Ecological studies of a fouling bryozoan, Bugula neritina - II. Suitable food plankton for growth of a bryozoan Bugula neritina under laboratory conditions.

Abstract

Two slide glasses each bearing three to five larvae of Bugula neritina attached had been placed in a one-liter beaker holding 800m/ of filtered seawater. After the daily renewal, adequate volume (10-60m/) of the cultured plankton was supplied into the beaker to make the food suspension at a definite density. The geometric means of the zooid number per colony after ten-day's culture with various food planktons were determined to compare the dietary effect. The salinity and temperature of culture water were maintained from 33.4 to 34.3‰ and from 21 to 23°, respectively. Of 24 species examined, Rhodomonas sp. supported the best growth; all young colonies exponentially increased the zooid number, from one to 72 in ten days. The growth was almost equal to that under the best natural conditions. Oxyrrhis marina cultured in the medium enriched with yeast extract was the most suitable food next to Rhodomonas (48 zooids in ten days). When fed on Dunaliella tertiolecta and Prorocentrum obtusidens, the colonies increased the zooid number only to 18 and 12, respectively. Diatoms and armored planktons had no dietary value for the animal.