Ecology of Pectinatella magnifica and associated algae and cyanobacteria

Abstract

The freshwater bryozoan species Pectinatella magnifica was found in 6 sandpits and in 19 mostly extensively managed ponds in the Protected Landscape Area and Biosphere Reserve Třeboňsko (Czech Republic) from its first record (in 2003) to 2012. Mean fresh biomass and abundance of P. magnifica colonies were 0.6 ± 1.5 kg m−2 and 0.7 ± 1.1 colony m−2 (± SD), respectively, in the shoreline zone during the growing season 2006–2011. The maximum biomass was mostly recorded during the first half of August in all basins. Colonization of further localities was recorded rather than increasing of P. magnifica biomass or abundance in 2012. There were no correlations between water temperature or water transparency and biomass/abundance of P. magnifica during the growing season. P. magnifica colonies preferred to grow on the branches or roots (especially of Salix sp.) to aquatic macrophytes and stones. Most of the water bodies, where this bryozoan species occurred, had lower concentration of total phosphorus in the water when compared with the typical fishponds in the Czech Republic. Inner space of colonies of P. magnifica provided suitable higher trophic level substrate when compared with the water of the sandpits/fishponds especially for green coccal algae. A massive algal colonization was indentified in decomposing colonies at the end of the growing season.