Pluses and minuses of ammonium and nitrate uptake and assimilation by phytoplankton and implications for productivity and community composition, with emphasis on nitrogen‐enriched conditions

By P. Glibert, F. Wilkerson, Richard C. Dugdale, J. Raven, Chris L. Dupont, Peter R. Leavitt, A. Parker, J. Burkholder, T. Kana. 2016

661 citations recorded by the source corpus.

Anthropogenic activities are altering total nutrient loads to many estuaries and freshwaters, resulting in high loads not only of total nitrogen (N), but in some cases, of chemically reduced forms, notably NH4+ . Long thought to be the preferred form of N for phytoplankton uptake, NH4+ may actually suppress overall growth when concentrations are sufficiently high. NH4+ has been well known to be inhibitory or repressive for NO3‐ uptake and assimilation, but the concentrations of NH4+ that promote vs. repress NO3‐ uptake, assimilation, and growth in different phytoplankton groups and under different growth conditions are not well understood. Here, we review N metabolism first in a “generic” eukaryotic cell, and the contrasting metabolic pathways and regulation of NH4+ and NO3− when these substrates are provided individually under equivalent growth conditions. Then the metabolic interactions of these substrates are described when both are provided together, emphasizing the cellular challenge of balancing nutrient acquisition with photosynthetic energy balance in dynamic environments. Conditions under which dissipatory pathways such as dissimilatory NO3− / NO2− reduction to NH4+ and photorespiration that may lead to growth suppression are highlighted. While more is known about diatoms, taxon‐specific differences in NH4+ and NO3− metabolism that may contribute to changes in phytoplankton community composition when the composition of the N pool changes are presented. These relationships have important implications for harmful algal blooms, development of nutrient criteria for management, and modeling of nutrient uptake by phytoplankton, particularly in conditions where eutrophication is increasing and the redox state of N loads is changing.

Subfields: Ecology, Oceanography, Pollution

View Paper: https://www.semanticscholar.org/paper/58fbcfb3a1aaa10e9b63ac02fa7a476a8304bd99

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Citations in the corpus

From Elements to Function: Toward Unifying Ecological Stoichiometry and Trait-Based Ecology (2017, background): “While we may expect higher biomass of small phytoplankton at lower N:P supply due to their generally fast growth (and thus high P requirements), higher picophytoplankton densities are only observed under high N:P conditions (Figure 1; Glibert, 2016) which is likely caused by changes in N redox and r”
Microbial Nitrogen Cycling in Estuaries: From Genes to Ecosystem Processes (2018, background): “…can also have distinct impacts on estuarine N cycling, these processes have been reviewed extensively elsewhere (Regnault 1987; Hecky and Kilham 1988; Valiela et al. 1997; Prins et al. 1998; Flindt et al. 1999; Anderson et al. 2002; Newell 2004; Boynton and Kemp 2008; Glibert et al. 2016).”
Diatom bloom‐derived bottom water hypoxia off the Changjiang estuary, with and without typhoon influence (2017, background): “…with high nutrient concentrations, diatoms have been found to be the dominant phytoplankton species (Furuya et al. 2003; Howarth and Marino 2006; Glibert et al. 2016), and the development of hypoxic conditions in summer is strongly associated with their presence (Cloern 2001; Turner et al.…”