| Abstract: | Riverine mussel investigations involve laborious fieldwork, yet acquiring adequate sample sizes is of high importance. This paper presents the calculated minimum sample size required for the bank‐to‐bank transect method in species‐poor rivers. Data were collected from 50 transect dives from four Finnish rivers, and individual‐based rarefaction calculations were used to detect the minimum sample size at which the number of new species plateaus (i.e., species richness curve reaches an asymptote). The results indicate that a minimum of 100 mussels per transect is necessary for general semiquantitative investigations using bank‐to‐bank transect surveys. Because riverine systems typically exhibit high variation in habitats, expert evaluation should always be used to determine the number and location of transects. The effort must be increased if very rare species need to be collected. |
