- Title
- Baseline isotopic data for Wolffia spp.: another option for tracing N-loading in freshwater systems?
- Creator
- Hill, Jaclyn M
- Date
- 2018
- Type
- text
- Type
- article
- Identifier
- http://hdl.handle.net/10962/68721
- Identifier
- vital:29308
- Identifier
- https://0-doi.org.wam.seals.ac.za/10.1086/696126
- Description
- δ15N values of aquatic plants can reflect anthropogenic N loading. Recent work suggests the duckweed Spirodela spp. effectively maps N loading in freshwater ecosystems, but its use may be complicated by a cyanobacterium–duckweed symbiosis that could reduce its utility in low-nutrient environments. I aimed to evaluate the potential of a 2nd duckweed species Wolffia spp., which lacks a cyanobacterial symbiosis, for use in pollution monitoring in freshwater ecosystems. I used a series of laboratory experiments to investigate δ15N equilibration rates and concentration-level effects of single-source N solutions in plant tissue over 16 d to provide baseline data for sewage-plume mapping with Wolffia spp. I also tested concentration-level effects in multisource solutions to investigate the effects of mixed-source inputs. Wolffia reflected environmental N sources with a 12- to 16-d isotopic equilibration time and showed enriched and depleted δ15N ratios for manure and KNO3 solutions, respectively, but distinguished poorly between lower concentrations of manure. Fractionations at isotopic equilibrium were opposite to expectations and decreased with increasing [N]. Wolffia showed a consistent preference for NH3 in mixed-source treatments, regardless of the proportion or concentration of NH3 or NO3– available, and a capacity for N storage, which may complicate mapping of N-loading in natural environments. Wolffia is likely to be a less useful bioindicator than the previously tested Spirodela. Future research should focus on field applications of Spirodela spp. to test its capacity for sewage-plume mapping of freshwater ecosystems in a natural environment.
- Format
- 8 pages, pdf
- Language
- English
- Relation
- Freshwater Science, Hill, J M, 2018. Baseline isotopic data for Wolffia spp.: another option for tracing N-loading in freshwater systems?. Freshwater Science, 37(1), pp.23-30, Freshwater Science volume 37 number 1 23 30 March 2018 2161-9565
- Rights
- Freshwater Science
- Rights
- Use of this resource is governed by the terms and conditions of the National Library of South Africa Copyright Act
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Collections
Hill, Jaclyn Marie (Ms)
RU Department of Zoology and Entomology
SDG 14. Life Below Water
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