Latitudinal study of the role of dimethylsulphoniopropionate in marine microbial foodwebs
- Publication Type:
- Thesis
- Issue Date:
- 2020
Open Access
Copyright Clearance Process
- Recently Added
- In Progress
- Open Access
This item is open access.
Dimethylsulphoniopropionate (DMSP) is a sulphur compound produced by some species of phytoplankton, coral and bacteria. It acts as a cryoprotectant, compatible osmolyte and antioxidant, and can provide high value nutrients for the whole marine microbial community. Nevertheless, research on DMSP has focused largely on its bacterial degradation to dimethylsulfide (DMS), a climatically active gas that potentially regulates local climate through an increase in cloud albedo. Therefore, other aspects of DMSP cycling, like DMSP utilisation by the marine microbial community, and especially by phytoplankton, are poorly understood. Marine sulphur dynamics, including DMSP production, cycling and DMS flux vary geographically across latitudinal space with different oceanographic characteristics resulting in different DMSP concentrations and microbial communities.
This thesis aimed to improve our understanding of the utilisation of DMSP by marine microbial communities from different oceanographic regions –the tropics (both coral-influenced and oligotrophic open waters), off shore temperate seas of mixed water masses, and late summer polar coastal waters— by investigating (1) the uptake of DMSP by different fractions of the marine microbial community, and (2) by identifying microbes that benefit from the presence of DMSP. This was achieved through a series of field-based studies that incubated natural oceanic waters enriched with DMSP over different time frames. Short incubations of 6-8 h were conducted to determine rapid DMSP uptake by the community following the progression of DMSP concentrations over time. The size separation of the community by serial filtration allowed for the quantification of DMSP that had been taken up by the microbes from the different size classes of the community. Longer incubations of up to 144 h were important for establishing longer-term responses, such as metabolism or fate of DMSP enrichment within the microbial community and DMSP-induced community shifts. Using sequencing information over time, we were also able to ascertain whether DMSP enrichment lead to any changes in DMSP metabolism and marine microbial structure.
Overall, the findings of this thesis challenge the idea that prokaryotes are the major DMSP sinks in the marine environment. Moreover, this thesis shows that phytoplankton uptake of DMSP is a common characteristic across different environments, with diatoms being one of the predominant sinks in the ocean. It has also shown that DMSP supposes an ecological advantage to many bacteria and some phytoplankton taxa, highlighting the need for more research on DMSP degradation pathways in both bacteria and phytoplankton.
Please use this identifier to cite or link to this item: