Project title: Ecosystem metabolism and nutrient spiralling in macrophyte-rich streams
Period: 2009 – 2013
Funding: The Danish National Research Foundation
Objectives
The proposed project will identify how stream ecosystem function in terms of spatial and temporal
variability of stream metabolism and nutrient spiralling relates to the abundance, distribution and
community composition of macrophytes in temperate lowland streams. The aims are (1) to understand
spatial and temporal changes in stream metabolism and nutrient spiralling in relation to macrophyte
biomass and biomass distribution; (2) to understand how morphology and biomass-specific rates of
macrophyte species affect stream metabolism and nutrient spiralling, and (3) to identify short term
changes in stream metabolism in macrophyte-rich streams and analyse the primary drivers controlling
these changes.
Introduction
Primary production and respiration are important controllers of ecosystem biomass and energy flow.
Stream metabolism measurements provide data on these two fundamental ecosystem functions in terms
of gross primary productivity (GPP) and community respiration (CR) [1, 2]. GPP is the organic matter
produced within the ecosystem and CR is an indication of the total consumption of organic matter supplied
both within and from outside the ecosystem. Comparisons of the patterns of GPP and CR over temporal
and spatial scales are important to obtain better understanding of the fundamental controls on these
ecosystem processes [3] and the energy flow in streams [4, 5].
Besides GPP and CR another key process in stream ecosystem function is nutrient cycling. In
streams nutrients such as phosphorus and nitrogen undergo transformations from dissolved available form
in the water column to uptake by organisms or by physical retention. The nutrient cycle is complete when
the nutrients return to the water column. Nutrient cycling in streams are accompanied by a downstream
transport and is therefore termed nutrient spiralling [6-8]. Nutrient spiralling measurements provide data
on nutrient uptake rate (vf), which provides a relative measure of how well a stream ecosystem can process
nutrients. Moreover, nutrient uptake length (Sw) and area based nutrient uptake rate (U) are calculated
according to standardized protocols [8, 9].
Measurements of ecosystem function in terms of stream metabolism and nutrient spiralling
provide direct information on how a stream is functioning as a whole rather than having to infer such
information from other water-quality measurements. Most studies of stream metabolism and nutrient
spiralling have been conducted in streams where primary production is dominated by benthic algae [1013]. Much less is known about stream metabolism and nutrient spiralling in streams dominated by
macrophytes (but see [14, 15, 16]). This project will specifically provide data on the spatial and temporal
dynamic in stream ecosystem function in terms of metabolism and nutrient spiralling in temperate
macrophyte-rich streams in relation to morphology and growth characteristics of the vegetation.
Specific aims
Aim 1. To understand spatial and temporal changes in stream metabolism and nutrient spiralling in relation
to macrophyte biomass and biomass distribution.
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Aim 2. To understand how morphology and biomass of macrophyte species affect stream metabolism and
nutrient spiralling.
Aim 3. To identify short term changes in stream metabolism in macrophyte-rich streams and analyse the
primary drivers controlling these changes.
The studies will be based on extensive field work including long term mesurements of oxygen dynamic in
streams for determining metabolism during the seasons, and nutrient release for determining nitrogen
uptake and turn-over rates in macrophyte rich streams.
References
[1] Odum, H. T. 1956. Primary production in flowing waters. Limnology and Oceanography, 1, 102-117
[2] Bott, T. L. 2006. Primary productivity and community respiration, pp. 663-690. In: F. R. Hauer and G. A. Lamberti,
eds. Methods in Stream Ecology, 2nd ed. Elsevier, New York.
[3] Cole, J., Lowett, G., Findlay, S. (eds.) 1991. Comparative Analysis of Ecosystems. Springer-Verlag, New York
[4] Dodds, W.K. 2007. Trophic state, eutrophication and nutrient criteria in streams. TRENDS in Ecology and Evolution,
22, 669-676
[5] Dodds, W.K., Cole, J.J. 2007. Expanding the concept of trophic state in aquatic ecosystems: It’s not just autotrophs.
Aquatic Sciences, 69, 427-439
[6] Webster, J.R., Patten, B.C.. 1979. Effects of watershed perturbation on stream potassium and calcium dynamics.
Ecological Monographs, 49, 51–72
[7] Newbold, J.D., Elwood, J.W., O'Neil, R.V., Van Winkle, W. 1981. Measuring nutrient spiraling in streams. Canadian
Journal of Fisheries and Aquatic Sciences 38:860–863
[8] Stream Solute Workshop. 1990. Concepts and methods for assessing solute dynamics in stream ecosystems.
Journal of the North American Benthological Society, 9, 95–119
[9] Webster, J.B., Valett, H.M. 2006. Solute dynamics. In: Hauer, F.R. & Lamberti, G.A. (eds.) Methods in
stream ecology. Academic Press
[10] Mulholland, P.J., Newbold, J.D., Elwood, J.W., Ferren, L.A., Webster, J.R. 1985. Phosphorus spiralling in a
woodland stream: seasonal variations. Ecology, 66, 1012–1023
[11] Mulholland, P.J., Tank, J.L., Sanzone, D.M., Wollheim, W.M., Peterson, B.J., Webster, J.R., Meyer, J.L. 2000.
Nitrogen cycling in a forest stream determined by a 15N tracer addition. Ecological Monographs, 70, 471-493.
[12] Newbold, J. D., Bott, T.L., Kaplan, L.A. 2006. Uptake of nutrients and organic C in streams in the New York City
drinking-water-supply watersheds. Journal of the North American Benthological Society 25, 998-1017.
[13] Bott, T. L., Montgomery, D.S., Arscott, D.B., Newbold, J.D., Dow, C.L. 2006. Ecosystem metabolism in streams of
the Catskill Mountains (Delaware and Hudson River watersheds) and Lower Hudson Valley. Journal of the North
American Benthological Society, 25, 1018-1044.
[14] Wilcock, R.J., Scarsbrook, M.R., Cooke, J.G., Costley, K.J., Nagels, J.W. 2004. Shade and flow effects on ammonia
retention in macrophyte-rich streams: implications for water quality. Environmental Pollution, 132, 95-100
[15] Gücker, B., Pusch, M.T. 2006. Regulation of nutrient uptake in eutrophic lowland streams.
Limnology and Oceanography, 51, 1443-1453.
[16] Simon, K.S., Niyogi, D.K., Frew, R.D., Townsend, C.R. (2007) Nitrogen dynamics in
grassland streams along a gradient of agricultural development. Limnology and Oceanography, 52,
1246-1257.
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