Thesis
The transformation and fate of microphytobenthos carbon and nitrogen within subtropical intertidal sediments
Southern Cross University
Doctor of Philosophy (PhD), Southern Cross University
2017
DOI:
https://doi.org/10.25918/thesis.66
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Abstract
13C or 15N and phospholipid fatty acids or D/L-Alanine were used to examine the uptake and partitioning of organic matter within intertidal sediment. The uptake of algal-derived dissolved organic nitrogen (DON) and dissolved inorganic nitrogen (DIN) were compared during application under in situ field conditions and in laboratory slurries. There was significantly reduced uptake of algal-derived DON compared to uptake of DIN within both experiments. Laboratory slurry experiments also did not reliably reflect in situ conditions. An experiment looking at the fate and processing pathways for microphytobenthos (MPB) carbon (C) and nitrogen (N) found that dissolved inorganic C (DIC) and DON were the largest export pathways to the water column for newly fixed material. These export pathways responded to nutrient loading in opposite ways, with DIC export increasing and DON export decreasing with increased nutrient availability. Increased turnover of MPB-derived material was observed within the sediment, with decreased retention of MPB-derived material within the microbial community. Finally, it was observed that increased nutrient availability combined with a pulse of labile MPB derived material resulted in the increased breakdown and export of existing sediment organic matter, i.e., a significant “priming” effect. This dissolved organic carbon (DOC) efflux pathway resulted in considerable additional export of increasingly refractory and older DOC resulting from the stimulated breakdown of native sediment organic matter as was confirmed by aromaticity and radiocarbon dating. Increased nutrient availability stimulated the increased turnover of MPB-C and N within the sediment and considerably altered processing pathways within the benthos.
Details
- Title
- The transformation and fate of microphytobenthos carbon and nitrogen within subtropical intertidal sediments
- Creators
- Philip Riekenberg
- Contributors
- Joanne Margaret Oakes (Supervisor) - Southern Cross UniversityBradley D Eyre (Supervisor) - Southern Cross University
- Awarding Institution
- Southern Cross University; Doctor of Philosophy (PhD)
- Theses
- Doctor of Philosophy (PhD), Southern Cross University
- Publisher
- Southern Cross University
- Number of pages
- xiv, 167 pages
- Identifiers
- 991012883700502368
- Copyright
- Copyright P Riekenberg 2017
- Academic Unit
- Faculty of Science and Engineering; School of Environment, Science and Engineering; Science
- Resource Type
- Thesis