The composition of gut microbes affects host weight, immune function, and disease status, and is sensitive to diet, environment, and pharmaceutical exposure. The gut microbiome modulates the toxicity and bioavailability of chemical stressors, however the effects of chemicals on the gut microbiome of aquatic biota are largely unknown. The Waterloo and Kitchener wastewater treatment plants (WWTPs) release effluents containing antibiotics, pharmaceuticals, and other contaminants into the Grand River (ON) that may negatively affect the gut microbiome of downstream organisms. In this study done in Fall 2018, I collected freshwater mussels (Lasmigona costata), several species of insect larvae, and riparian spiders (Tetragnathidae) from sites upstream and downstream of these WWTPs. The gut microbiome was analyzed following the extraction, PCR amplification, and sequencing of bacterial DNA using the V3-V4 hypervariable regions of the 16S rRNA genetic barcode. Changes in the relative abundance of major gut microbiome phyla were observed in all targeted aquatic organisms downstream of WWTPs except Hydropsychidae. Shannon alpha diversity, a measure of bacterial abundance and evenness, differed significantly among sites for mussels (one-way ANOVA: F=7.894, p=0.001), spiders (F=4.788, p=0.01), Perlidae (F=3.1, p=0.0056), Hydropsychidae (F=3.674, p=0.0014), and Heptageniidae (F=2.715, p=0.0143), but not for Baetidae and Ephemerellidae. In sites downstream of the Waterloo WWTP, alpha diversity decreased in spiders, while in sites downstream of the Kitchener WWTP diversity decreased in mussels and Perlidae, while increasing for spiders. Bray-Curtis beta diversity, a measure of dissimilarity between bacterial communities, was significantly dissimilar among sites in all invertebrate taxa (Permanova: p<0.02). Upstream sites differed from downstream Waterloo sites in spiders, Perlidae, and Hydropsychidae (Adonis pairwise: p<0.05), while upstream mussels, spiders, Perlidae, and Hydropsychidae differed from downstream Kitchener sites (p<0.05). Additionally, effluent-derived bacteria were found in the microbiomes of aquatic invertebrates downstream of the WWTPs and not upstream. Taxa was also a significant driver of bacterial composition and diversity in invertebrates. These results indicate that the gut microbiome of downstream organisms differed from the bacterial composition observed in the same invertebrate taxa upstream of the WWTPs, potentially leading to altered host health. This adds to our understanding of how chemical stressors impact the gut microbiome of aquatic and riparian biota; however, future studies are needed to investigate linkages between the gut microbiome and health of these species. / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/25756 |
| Date | January 2020 |
| Creators | Millar, Elise |
| Contributors | Kidd, Karen, Biology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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