Food selection by Plumatella geimermassardi Wood and Okamura, 2004 (Phylactolaemata, Bryozoa)

Abstract

Bryozoans are sessile filter feeding organisms able to play an important role in the cycling of organic matter in freshwater ecosystems. However, the quality and quantity of food particles ingested by bryozoans are still not well-known. Therefore, an experimental design was performed in order to investigate the clearance rate (CR), food selection and efficiency of assimilation by the freshwater bryozoan species Plumatella geimermassardi. P. geimermassardi was collected from the Colfiorito Marsh (Umbrian Natural Park, Italy), during summer. A higher grazing rate of suspended and dissolved solids was evidenced in the colonies collected in June, July, than in August. Food selection and assimilation of phytoplankton were determined. The algal species ingested as diet food item and those excreted with the faecal pellets were taxonomically identified. The results provide new information on CR and food selection by P. geimermassardi and enhance knowledge on its biology. Insights on feeding preferences by bryozoan species can provide valid information about their feasible distribution and abundance.

Keywords

• assimilation
• clearance rate
• dissolved and suspended solids
• freshwater bryozoans
• phytoplankton