Assessment of fish communities using eDNA: effect of spatial sampling design in lentic systems of different sizes

Freshwater fish biodiversity is quickly decreasing and requires effective monitoring and conservation. Environmental DNA (eDNA)-based methods have been shown to be highly sensitive and cost-efficient for aquatic biodiversity surveys, but few studies have systematically investigated how spatial sampling design affects eDNA-detected fish communities across lentic systems of different sizes. We compared the spatial patterns of fish diversity determined using eDNA in three lakes of small (SL; 3 ha), medium (ML; 122 ha) and large (LL; 4,343 ha) size using a spatially explicit grid sampling method. A total of 100 water samples (including 9, 17, and 18 shoreline samples and 6, 14, and 36 interior samples from SL, ML, and LL, respectively) were collected, and fish communities were analyzed using eDNA metabarcoding of the mitochondrial 12S region. Together, 30, 35, and 41 fish taxa were detected in samples from SL, ML, and LL, respectively. We observed that eDNA from shoreline samples effectivel...