Author: Ian Smith
As more housing developments are built in Canada, more stormwater drainage ponds will be built to accompany them. However, drainage ponds can serve as vectors for aquatic invasive species resulting from human introductions. Many of these ponds, for example, become overrun with goldfish – likely from unwanted pets being released. However, these small ponds can serve as great tools to investigate the effectiveness of eDNA for invasive aquatic species detection and community biodiversity assessments. The small sizes allows for complete census of fish populations inhabiting them. Working with DFO, we compared the concentration of goldfish eDNA determined via qPCR to the known number of goldfish that were collected from draining events. After allometrically scaling the fish populations to account for differences in size, we found that there was a positive correlation between the eDNA concentration and the numerical abundance of goldfish populations, particularly highlighting the importance of accounting for juveniles in high-density populations. We also investigated the use of metabarcoding primers (M-Mito and PS1) to determine fish community composition from eDNA samples. DFO had performed depletion surveys on the storm drain ponds to construct their own estimates of population abundances to compare to our results. We found that there was some overlap of the species detected from both estimates, with a high degree of overlap for the most commonly detected species; discrepancies between survey methods more often occurred for less abundant species. We will further compare relative read abundance to relative abundance data generated from the DFO fish surveys conducted using traditional methods.
