Previous studies have suggested the occurrence of spatial variability in the fish food web structure in the temperate Wadden Sea. However, these studies were carried out in different years and with different fishing devices. To eliminate interannual variability in fish abundance and the impact of sampling design, an environmental DNA (eDNA) study was performed monthly at eight locations over the spatial scale of the Dutch Wadden See year-round in 2018-2019. In total, 40 different individual fish species and 8 fish groups were identified. The number of fish species identified in the samples varied over time and among locations between three and 19 different fish species. Over the year, 20 species were identified at all locations; eight species were found at 6-7 locations and the remaining 30 species were found only incidentally. The spatial variability found in the Wadden Sea fish community is the result of the variability in presence of rare (transient) species, due to location specific differences in hydrographical and geomorphological characteristics.
