Distribution of phytoplankton in a German lowland river in relation to environmental factors

Journal of Plankton Research, May 2011

In comparison to lentic systems, the species composition and community structure of phytoplankton in lotic habitats are still poorly understood. We investigated the spatial and temporal dynamics of the phytoplankton community in a German lowland river, the Kielstau catchment, and the relationships with environmental variables. Among the 125 taxa observed, Desmodesmus communis, Pediastrum duplex and Discostella steligera were dominant species at lentic sites while Tabellaria flocculosa, Euglena sp., Planothidium lanceolatum, Cocconeis placentula and Fragilaria biceps dominated at lotic sites. Remarkable spatial and temporal variations of the phytoplankton community were revealed by non-metric multidimensional scaling. Canonical correspondence analysis indicated that physical factors (e.g. hydrological variables) and major nutrients [e.g. total phosphorus, dissolved inorganic nitrogen (DIN)] were of equal importance controlling the variation in structure of riverine phytoplankton assemblages. Weighted averaging regression and cross-calibration produced strong models for predicting DIN, water temperature (WT) and total suspended solid (TSS), which enabled the selection of algal taxa as potentially sensitive indicators: for DIN, Ulnaria ulna var. acus, U. ulna, D. communis and Euglena sp.; for WT: D. steligera, Scenedesmus dimorphus, D. communis and Euglena sp.; for TSS, Nitzschia sigmoidea, D. communis and Oscillatoria sp. The results from this relatively small survey indicate the need for further monitoring to gain a better understanding of riverine phytoplankton and to capitalize on the environmental indicator capacity of the phytoplankton community.

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Distribution of phytoplankton in a German lowland river in relation to environmental factors

In comparison to lentic systems, the species composition and community structure of phytoplankton in lotic habitats are still poorly understood. We investigated the spatial and temporal dynamics of the phytoplankton community in a German lowland river, the Kielstau catchment, and the relationships with environmental variables. Among the 125 taxa observed, Desmodesmus communis, Pediastrum duplex and Discostella steligera were dominant species at lentic sites while Tabellaria flocculosa, Euglena sp., Planothidium lanceolatum, Cocconeis placentula and Fragilaria biceps dominated at lotic sites. Remarkable spatial and temporal variations of the phytoplankton community were revealed by non-metric multidimensional scaling. Canonical correspondence analysis indicated that physical factors (e.g. hydrological variables) and major nutrients [e.g. total phosphorus, dissolved inorganic nitrogen (DIN)] were of equal importance controlling the variation in structure of riverine phytoplankton assemblages. Weighted averaging regression and cross-calibration produced strong models for predicting DIN, water temperature (WT) and total suspended solid (TSS), which enabled the selection of algal taxa as potentially sensitive indicators: for DIN, Ulnaria ulna var. acus, U. ulna, D. communis and Euglena sp.; for WT: D. steligera, Scenedesmus dimorphus, D. communis and Euglena sp.; for TSS, Nitzschia sigmoidea, D. communis and Oscillatoria sp. The results from this relatively small survey indicate the need for further monitoring to gain a better understanding of riverine phytoplankton and to capitalize on the environmental indicator capacity of the phytoplankton community. doi:10.1093/plankt/fbq139, available online at www.plankt.oxfordjournals.org. Advance Access publication November 9, 2010 # The Author 2010. Published by Oxford University Press. All rights reserved. For permissions, please email: - I N T R O D U C T I O N Phytoplankton have been studied extensively in lentic fresh waters (lakes and reservoirs) where long residence time and low flow velocity allow sufficient time for growth and reproduction (e.g. Basu and Pick, 1997; Sabater et al., 2008; Torremorell et al., 2009). However, in comparison to lentic systems, the species composition and community structure of phytoplankton in lotic systems (streams and rivers) are still poorly understood (Basu and Pick, 1996; Piirsoo et al., 2008). The spatial and temporal pattern of a community are of crucial importance for understanding ecosystem functioning because they can affect ecosystem processes, functioning and stability and reflect major shifts in environmental conditions (Suikkanen et al., 2007; Zhou et al., 2009a). Distribution patterns of phytoplankton are strongly correlated with environmental factors (Lepisto et al., 2004). Possible factors may be physical [climate, water temperature (WT), light intensity], chemical (nutrient concentrations) (Reynolds et al., 1993; Torremorell et al., 2009), hydrological (river morphology, discharge, water residence time, precipitation) (Descy and Gosselain, 1994; Kiss et al., 1994; Skidmore et al., 1998) and biotic (grazing, competition, parasitism) (Moss and Balls, 1989; Ha et al., 1998). Unfortunately, there is no general consensus as to which factors regulate phytoplankton communities in lotic habitats (Basu and Pick, 1995). Besides, contributions of the main environmental factors to phytoplankton variations are also unclear. For example, hydrological factors are thought to be of greater importance to planktonic development in rivers than in lakes (Pace et al., 1992), whereas other researchers concluded that river phytoplankton is more strongly regulated by nutrient concentrations, such as total phosphorus concentration (Soballe and Kimmel, 1987; Moss and Balls, 1989; Basu and Pick, 1996; Van Nieuwenhuyse and Jones, 1996). The response of phytoplankton to environmental factors has become a central topic of current research (Buric et al., 2007), and identification of the main factors controlling phytoplankton in a particular water body is essential for choosing an appropriate management strategy for the maintenance of a desired ecosystem state (Peretyatko et al., 2007). Lowland rivers, characterized by specific properties, such as low hydraulic gradients, shallow groundwater and high potential for water retention in peatland and lakes (Schmalz and Fohrer, 2010), are apparently different from the habitats of lakes and mountain streams. Until now, studies of phytoplankton communities in lowland rivers, to our knowledge, are still scanty. In this paper, we investigated the spatio-temporal variation of the phytoplankton community and environmental variables over a 1-year period (November 2008 August 2009) throughout a lowland river ecosystem in northern Germany. The objectives of this study were to: (i) describe the distribution patterns in the species composition and biomass of phytoplankton in the Kielstau catchment; (ii) stu (...truncated)


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Naicheng Wu, Britta Schmalz, Nicola Fohrer. Distribution of phytoplankton in a German lowland river in relation to environmental factors, Journal of Plankton Research, 2011, pp. 807-820, 33/5, DOI: 10.1093/plankt/fbq139