Pollutants and cryptic species: can toxicants alter the microbiome of cryptic species and influence their abiotic tolerances?

Master Thesis subject (30 ECTS)
Anthropogenic activities have been altering natural environments for decades, where contamination by man-made pollutants poses a great risk for ecosystem health and biological diversity. Environmental risk-assessment methods have been developed and applied in order to prevent and/or mitigate human impacts, like single-species toxicity tests. Single-species are widely used as bio-indicators of pollution and environmental degradation, and data resulting from such assays are often used by regulatory agencies in the establishment of environmental regulations. However, the existence of cryptic species requires attention and care when interpreting data from single-species assessments. Cryptic species are morphologically indistinguishable, but show consistent genetic differences and may show species-specific tolerances towards pollutants. This was already proven for cryptic species of the marine nematode Litoditis marina. Pollutants may also influence the microbiome (bacteria associated with the gut) of a species. A species’ microbiome may also be important for specific abiotic tolerances (e.g. salinity fluctuation) and was also proven to be different among the cryptic L. marina species. As a consequence, pollutants may not only influence the microbiome but also the abiotic tolerances of the species. In this thesis we will test if the microbiomes of the species will change depending on pollutants and if their tolerance for specific abiotic conditions will be influenced. An experiment will be conducted with different cryptic species, pollutants and abiotic conditions. Next Generation Sequencing will be used to determine the microbiome of the species and to elucidate the effect of pollutants on it.
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De Meester
Reference Number: RP-48391