Microbial biogeochemistry of estuarine sediments: linking biodiversity and ecosystem functioning

Master Thesis subject (30 ECTS)
Estuaries, at the interface between rivers and coasts, are highly productive ecosystems. When healthy, they harbor rich sediment communities that play an important role in the net metabolism of the ecosystem. Biogeochemical processes occurring within the sediment as well as the interactions with the water column determine to a large extent the overall dynamics and water quality in the ecosystem. These processes are to a large degree driven by highly diverse and dense microbial communities, e.g. nutrient recycling through decomposition and re-oxidation of organic matter, which in turn supports primary production and ultimately food provisioning for birds, fish and mammals. Understanding the mechanisms that drive and structure sediment biogeochemistry thus requires insight into the ecology of its microbial inhabitants and their potential interactions with other ecosystem components. For example, macrofaunal ecosystem engineering organisms, like bioturbating and bio-irrigating worms, shellfish, and crustaceans profoundly affect sediment organic matter, pore water movement and oxygen penetration that may facilitate or inhibit specific populations of distinct microbial functional groups. In this thesis, you will study how the biodiversity of microbial and macrofaunal communities in the Schelde estuary relate to the cycling of energy and matter. Therefore, you will use state-of-the art techniques including Next Generation Sequencing, PAM fluorescence, and benthic flux incubation measurements from sediments collected along the gradients in salinity, sediment granulometry and depth along the Schelde estuary. The obtained ecological understanding of biodiversity-ecosystem function relationships in this thesis will assist in future management of the Schelde estuary, which requires new strategies of ecomorphological management that allow accommodating sea level rise and in the meantime the maintenance of estuarine ecosystem services, such as the bioremediation of waste and nutrient cycling.
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Reference Number: RP-36212