The characteristics of ammonium and nitrate uptake by phytoplankton in Lake Kinneret1

Berman, T.; Sherr, Barry F.; Sherr, Evelyn B.; Wynne, David; McCarthy, James J.

doi:10.4319/lo.1984.29.2.0287

Cited by 62 publications

(37 citation statements)

References 29 publications

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“…During the crash period, high levels of ammonia-N and comparatively low levels of chlorophyll were measured in the water column. Under such conditions, phytoplankton in these ponds take up ammonia-N preferentially to nitrate (Krom et al 1989) as has been shown previously in other marine systems in both laboratory and field studies (Goldman 1976, Berman et al 1984.…”

Section: Resultssupporting

confidence: 70%

Importance of benthic productivity in controlling the flux of dissolved inorganic nitrogen through the sediment-water interface in a hypertrophic marine ecosystem

Krom¹

1991

Mar. Ecol. Prog. Ser.

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The rate of bacterial nitrate reduction measured directly .in sediments from a hypertrophic marine ecosystem (6.0 f 1.5 mm01 m-2 d-') was similar to the value calculated from a whole pond nutrient budget (7.7 f 0.3 mm01 m-' d-') during a phytoplankton crash period. Organic matter breakdown in the sediments represented the dominant source of ammonia-N to the system (16.09 mm01 m'.' d-l compared to 2.97 mm01 m-2 d.' directly from fish excretion and 0.28 mm01 m-2 d.' in the inflow). However most, if not all, of t h~s ammonia-N d~d not reach the water col~imn as shown by a total nutrient budget for the pond. It was intercepted by the benthic flora and used to support high levels of benthic productivity (246 mm01 0 m-2 d-'; 29.72 mm01 N m-2 d-l). The benthic productivity was calculated by correcting the total system gross production (determined by a total oxygen budget) for water column productivity measured by in situ Incubated light/dark bottles. It is suggested that benthic productivity by micro-and macroalgae may be important in a number of shallow water systems a s modifiers of the flux of ammonia-N from the sediment to the overlying waters.

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Section: Resultssupporting

confidence: 70%

Importance of benthic productivity in controlling the flux of dissolved inorganic nitrogen through the sediment-water interface in a hypertrophic marine ecosystem

Krom¹

1991

Mar. Ecol. Prog. Ser.

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“…These findings indicate active synthesis of protein by nanoplankton and picoplankton at night (Cuhel et al 1984). In contrast, Berman et al (1984) found a marked diurnal pattern of N uptake for both nanoplankton and the total algal community. Clearly factors other than cell size, such as population shifts and availability of carbohydrate reserves, are important considerations Table 2.…”

Section: Notesmentioning

confidence: 64%

Size-fractionated measurements of nitrogen uptake in aged upwelled waters: Implications for pelagic food webs

Probyn

1990

Limnol. Oceanogr.

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Uptake of NO3−, NH4+, and urea was measured for the 200–20‐, 20–2‐, and <2‐µm size classes within the chlorophyll maximum layer in the Benguela upwelling system. Picoplankton and nanoplankton dominated in terms of biomass and activity both inshore and offshore. Net plankton N uptake declined drastically at night, whereas the smaller size classes maintained rates close to daytime levels. There was some evidence for N resource partitioning. Reduced N generally made up a higher proportion of the total N uptake by nanoplankton and picoplankton (for both size classes, mean = 94%) than by net plankton (mean = 63%). The contribution of nanoplankton and picoplankton NH4+ uptake always exceeded 50% of the total primary N production. In a regeneration‐based model with small cells dominating primary production it is conservatively estimated that carnivory on microzooplankton can contribute 14% toward the production of an omnivorous mesozooplankton assemblage.

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“…The threshold for the effect of ammonium on nitrate uptake is quite variable, ranging in cultures from 0.1 to 90 LIM (Table 5 ) , and in the field from 0.1 to 15 CIM (Kuenzler et al 1979, Toetz 1981, Paasche & Kristiansen 1982, Berman et al 1984, Prjscu & Priscu 1984, Probyn 1985, Lipschultz et al 1986, Queguiner et al 1986, Pennock 1987. Considerable variation would be expected in thresholds because they probably result from a number of interacting biochemical processes (but the cause is currently unknown) and they are defined differently in various studies.…”

Section: Analysis Of Existing Data On Inhibitionmentioning

confidence: 99%

The interaction between ammonium and nitrate uptake in phytoplankton

Dortch¹

1990

Mar. Ecol. Prog. Ser.

661

416

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ABSTRACT. A basic tenet of nitrogen utilization in phytoplankton is that ammoniuln inhibits nitrate uptake. Consequently, it is generally believed that little or no nitrate uptake occurs at ammonium concentrations above ca 1 yM. A thorough review of field studies shows that the reduction of nitrate uptake rate in the presence of ammonium is rarely so severe, and that it is a highly variable phenomenon. To simplify quantification of the interaction between nitrate and ammonium uptake, it is proposed that it be divided into an indirect interaction, preference, and a direct effect, inhibition. In order to determine preference and inhibition it is necessary to measure uptake of each inorganic nitrogen source alone and in the presence of increasing concentrations of the other nitrogen source. Preference for ammonium uptake is manifested primarily in a higher V,,,,, and lower K, for ammonium uptake than for nitrate uptake and is accentuated by low light and low nitrogen availability. However, although ammonium is the preferred nitrogen source for uptake, growth rates on nitrate usually equal or exceed those on ammonium. Inhibition of nitrate uptake by ammonium is much more variable, but when separated from preference is less extreme. It is also enhanced by low light, but unlike preference, i t is greater when phytoplankton are N sufficient. Species differences are apparent for both preference and inhibition, but there are only enough data for preference to determine how it varies among algal groups. Finally, there are reports of low concentrations of ammonium stimulating nitrate uptake and of nitrate inhibiting ammonium uptake. Such unexpected interactions along with variations in preference and inhibition with species composition and environmental conditions may account for the variability observed in field studies and will not be explainable or predictable until more is known about the underlying biochemical mechanisms. Even though it is not possible at present to model nitrate uptake accurately because of uncertainty about the interaction between ammonluln and nitrate uptake, it is quite evident that the simplistic view that nitrate uptake is reduced to zero if ammonium exceeds 1 1iM would often result in large underestimates of nitrate uptake and new production.

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The characteristics of ammonium and nitrate uptake by phytoplankton in Lake Kinneret1

Cited by 62 publications

References 29 publications

Importance of benthic productivity in controlling the flux of dissolved inorganic nitrogen through the sediment-water interface in a hypertrophic marine ecosystem

Importance of benthic productivity in controlling the flux of dissolved inorganic nitrogen through the sediment-water interface in a hypertrophic marine ecosystem

Size-fractionated measurements of nitrogen uptake in aged upwelled waters: Implications for pelagic food webs

The interaction between ammonium and nitrate uptake in phytoplankton

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