Importance of substrate material for sustaining the bryozoan Pectinatella magnifica following summer rainfall in lotic freshwater ecosystems, South Korea

Abstract

We investigated the influence of summer rainfall on Pectinatella magnifica colonies in lotic ecosystems. Of the examined substrate materials, branches and aquatic macrophytes supported more colonies of P. magnifica than that by stones or artificial materials. The influence of rainfall on P. magnifica colonies differed in accordance with the type of substrate material at each study site. In the Geum River, little difference was noted in the number of P. magnifica colonies on branches before (mean ± SE, 24 ± 7.3 individuals) and after rainfall (20 ± 8.4 ind.); other substrate types supported fewer colonies of P. magnifica after rainfall. In contrast, in the Miryang River, rainfall had minimal effect on the number of P. magnifica colonies supported by macrophytes (13 ± 3.8 and 12 ± 4.3 ind., respectively). Artificial material was more abundant in the Banbyeon Stream where it was able to support more colonies of P. magnifica. We found that the structure of different substrates sustains P. magnifica following rainfall. In the Miryang River, free-floating and submerged plants with a relatively heterogeneous substrate surface were the dominant macrophytes, whereas in the Geum River, simple macrophytes (i.e., emergent plants) were dominant. Therefore, we conclude that the substrate type on which P. magnifica grows plays an important role in resisting physical disturbances such as rainfall.

Keywords

• macrophyte
• Pectinatella magnifica
• rainfall
• river
• substrate material