Figure 1
Geographical distribution across Denmark of the 47 analyzed marine samples from 2017–2018. Many samples overlap, explaining the limited number of sampling sites plotted.
Figure 2
Schematic overview of the project “DNA & Liv” (abbreviated DL) offered by the Natural History Museum of Denmark as a teaching programme for high school students. The figure icons above the boxes illustrate which parts of the process were conducted by a researcher or by citizens, respectively.
Figure 3
Citizens at work in the DNA laboratory, working with eDNA samples and analyses, October 2015. Photo by Anders P. Schultz.
Figure 4
Each species-specific qPCR analysis consisted of four tubes. Along with qPCR reagents, negative and positive control samples were added to the tubes with extracted eDNA obtained from filters. The positive control sample (blue) is a purified and diluted target DNA molecule initially obtained from the target species. The negative control sample (red) is double-distilled sterile water. The eDNA sample (green) is extracted DNA from the filter unit (a). The sigmoid amplification plot obtained from the PCR reaction (b) is a typical diagram and result of a qPCR assay. The increase in relative fluorescence levels reflects a higher number of DNA molecules present in the reaction tube for each cycle of amplification in the qPCR.
Figure 5
Share of valid controls conducted by citizens per species assay. The average success rate across species, 0.72, is marked by the dotted line.
Figure 6
Share of failed and successful control tests for the researcher and citizens pooled across the 14 species assays included in the comparison. See Table 1 for statistical results.
Table 1
Chi-squared test of difference in proportions of negative and positive control tests, performing as expected and failing to perform as expected, between researcher and citizens.
| RESEARCHER | CITIZENS | CHI-SQUARED VALUE | LEVEL OF SIGNIFICANCE | |
|---|---|---|---|---|
| Negative control being negative as expected/total | 130/138 | 1249/1310 | 0.36 | |
| Positive control being positive as expected/total | 889/930 | 989/1312 | 163.46 | *** |
| Failed negative controls/total | 8/138 | 61/1310 | 0.15 | |
| Failed positive controls/total | 41/930 | 323/1312 | 161.97 | *** |
[i] Note: Significance level: *** p = 0.01, ** p = 0.05, * p = 0.10.
Figure 7
Presence and absence data based on eDNA data for the Atlantic cod (Gadus morhua) (a) and the round goby (Neogobius melanostomus) (b). The presence and absence of the same two species but based on data from the official database, Fish Atlas, for Atlantic cod (c) and the round goby (d). Photo inserts of Atlantic cod (41 cm) and round goby (9.9 cm) by Henrik Carl.