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The trapping of organic matter within plant patches in the channels of the Okavango Delta : a matter of quality

Schoelynck, Jonas; Schaller, Jörg; Murray-Hudson, Mike; Frings, Patrick J. LU ; Conley, Daniel J. LU ; van Pelt, Dimitri; Mosimane, Keotshephile; Gondwe, Mangaliso J.; Wolski, Piotr and Meire, Patrick, et al. (2017) In Aquatic Sciences
Abstract

The role of in-stream aquatic vegetation as ecosystem engineers in the distribution of organic matter was investigated in the Okavango Delta, one of the world’s largest oligotrophic wetlands. The Okavango channel beds are covered up to 50% with submerged macrophyte patches. By accumulating and concentrating organic matter in the sediments below the patches, macrophytes are likely able to locally forestall a deficiency of nutrients. Up to 21 times more N, 18 times more C, 13 times more P and 6 times more Si can be found in vegetated sediments compared to non-vegetated sediments. Nutrient specific accumulation relates to its relative scarcity in the overlaying water. There is a depletion of dissolved N relative to P, whereas Si is... (More)

The role of in-stream aquatic vegetation as ecosystem engineers in the distribution of organic matter was investigated in the Okavango Delta, one of the world’s largest oligotrophic wetlands. The Okavango channel beds are covered up to 50% with submerged macrophyte patches. By accumulating and concentrating organic matter in the sediments below the patches, macrophytes are likely able to locally forestall a deficiency of nutrients. Up to 21 times more N, 18 times more C, 13 times more P and 6 times more Si can be found in vegetated sediments compared to non-vegetated sediments. Nutrient specific accumulation relates to its relative scarcity in the overlaying water. There is a depletion of dissolved N relative to P, whereas Si is relatively abundant. The Okavango Delta water can generally be characterised as oligotrophic based on plant species composition (e.g. presence of carnivorous plants and absence of floating plants), low plant N:P ratios, and low nutrient- and element-concentrations. Local mineralization and intensified nutrient cycling in the sediments is hypothesized to be crucial for the macrophytes’ survival because it provides a key source of the essential nutrients which plants otherwise cannot obtain in sufficient quantities from the nutrient poor water. By engineering the ecosystem as such, channel vegetation also retards the loss of elements and nutrients to island groundwater flow, contributing to one of the key processes driving the high productivity of the Okavango Delta, making it unique among its kind.

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publication status
epub
subject
keywords
Aquatic ecosystem, Carbon pools, Ecosystem engineering, Nutrient accumulation, Nutrient fixation, Organic rich sediments, Wetland
in
Aquatic Sciences
pages
14 pages
publisher
Birkhaüser
external identifiers
  • scopus:85018380409
  • wos:000405798900018
ISSN
1015-1621
DOI
10.1007/s00027-017-0527-2
language
English
LU publication?
yes
id
2329d494-1861-4c97-8181-4d0241e6976f
date added to LUP
2017-05-17 13:49:41
date last changed
2017-09-18 11:36:04
@article{2329d494-1861-4c97-8181-4d0241e6976f,
  abstract     = {<p>The role of in-stream aquatic vegetation as ecosystem engineers in the distribution of organic matter was investigated in the Okavango Delta, one of the world’s largest oligotrophic wetlands. The Okavango channel beds are covered up to 50% with submerged macrophyte patches. By accumulating and concentrating organic matter in the sediments below the patches, macrophytes are likely able to locally forestall a deficiency of nutrients. Up to 21 times more N, 18 times more C, 13 times more P and 6 times more Si can be found in vegetated sediments compared to non-vegetated sediments. Nutrient specific accumulation relates to its relative scarcity in the overlaying water. There is a depletion of dissolved N relative to P, whereas Si is relatively abundant. The Okavango Delta water can generally be characterised as oligotrophic based on plant species composition (e.g. presence of carnivorous plants and absence of floating plants), low plant N:P ratios, and low nutrient- and element-concentrations. Local mineralization and intensified nutrient cycling in the sediments is hypothesized to be crucial for the macrophytes’ survival because it provides a key source of the essential nutrients which plants otherwise cannot obtain in sufficient quantities from the nutrient poor water. By engineering the ecosystem as such, channel vegetation also retards the loss of elements and nutrients to island groundwater flow, contributing to one of the key processes driving the high productivity of the Okavango Delta, making it unique among its kind.</p>},
  author       = {Schoelynck, Jonas and Schaller, Jörg and Murray-Hudson, Mike and Frings, Patrick J. and Conley, Daniel J. and van Pelt, Dimitri and Mosimane, Keotshephile and Gondwe, Mangaliso J. and Wolski, Piotr and Meire, Patrick and Struyf, Eric},
  issn         = {1015-1621},
  keyword      = {Aquatic ecosystem,Carbon pools,Ecosystem engineering,Nutrient accumulation,Nutrient fixation,Organic rich sediments,Wetland},
  language     = {eng},
  month        = {05},
  pages        = {14},
  publisher    = {Birkhaüser},
  series       = {Aquatic Sciences},
  title        = {The trapping of organic matter within plant patches in the channels of the Okavango Delta : a matter of quality},
  url          = {http://dx.doi.org/10.1007/s00027-017-0527-2},
  year         = {2017},
}