Sulfur Cycling in Prymnesium parvum on the Norfolk Broads

Rivera, Peter (2020) Sulfur Cycling in Prymnesium parvum on the Norfolk Broads. Doctoral thesis, University of East Anglia.

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The Norfolk Broads, Britain’s largest protected wetland, has been plagued by series of harmful algal blooms (HABs) of Prymnesium parvum (haptophyceae) causing serious fish-kill events. I show that Hickling Broads P. parvum strains produce novel prymnesin toxins, more closely related to northern European strains than to those identified in the UK, potentially indicating recent invasion and colonisation event/s. P. parvum also produces the important organosulfur osmolyte dimethylsulfoniopropionate (DMSP), which is the major precursor for the climate-active gas dimethylsulfide (DMS) and an abundant marine nutrient. There have been no molecular studies investigating the natural cycling of DMSP by P. parvum nor of its effects on the microbial community structure. Despite the brackish nature of Broads water, P. parvum and DMSP, at levels up to 60 nM, were ever-present over a season. There was a strong correlation between the abundance of P. parvum, its DSYB DMSP synthesis gene transcripts and DMSP, suggesting this HAB alga as the major DMSP producer. P. parvum strains did not produce DMS itself, and despite significant DMSP levels in Broads water, bacteria with the potential to catabolise DMSP through the DddP DMSP lyase or DmdA DMSP demethylase were rare or undetected in Broads water, respectively. This is consistent with DMSP having an important role in these organisms and these catabolic systems being marine. P. parvum strains of diverse origin (freshwater, brackish and marine) all produced DMSP at similar levels throughout their life cycle, which was upregulated during late exponential to early stationary phase and by raised salinity, consistent with stress response and osmoregulatory functions. This case study provides novel insights to the role of brackish water HAB in DMSP dynamics of lake systems, their role in local biogenic sulfur cycling, and the prymnesin toxins they produce.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 23 Aug 2022 07:38
Last Modified: 23 Aug 2022 07:38

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