The time‐course of uptake of inorganic and organic nitrogen compounds by phytoplankton from the Eastern Canadian Arctic: A comparison with temperate and tropical populations

Harrison, W. G.

doi:10.4319/lo.1983.28.6.1231

Cited by 34 publications

(16 citation statements)

References 11 publications

(16 reference statements)

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“…For Chesapeake Bay phytoplankton, where relatively severe nitrogen stress was demonstrated, Glibert & McCarthy (1984) found that the uptake rate of nitrate was only mildly enhanced, whereas ammonium uptake rates were enhanced 5-to 10-fold relative to longer incubations. Other examples of significant enhancement in ammonium uptake rates were in the surf zone along the northwest coast of USA (Collos & Lewin 1974), an estuary in North Carolina (Fisher et al 1981), Chesapeake Bay (Wheeler et al 1982), in the Canadian Arctic (Harrison 1983) and in a freshwater lake (Priscu 1987). Rapid ammonium uptake has also been observed in intertidal seaweeds grown under field conditions (Thomas & Harrison 1987).…”

Section: Ecological Implicationsmentioning

confidence: 99%

Determination of nutrient uptake kinetic parameters: a comparison of methods

Harrison¹,

Parslow²,

Conway³

1989

Mar. Ecol. Prog. Ser.

163

132

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Three methods which have been used to determine nutrient uptake hnetic parameters were compared using steady-state NH,-limited cultures of the chrysophyte Pseudopedinella pyriforrnis. The first 2 methods involved a multiple flask incubation where different concentrations of substrate were added to each flask. Method 1 used a variable incubation time, while the incubation time of Method 2 was short and constant. The third method, the perturbation method, involved one large addition of the substrate to one culture and hence the nutritional past history varied throughout the experiment. This method was used also with the diatoms Skeletonema costatum and Chaetoceros debilis in Si-Limited chemostats. Results inhcate that, for nutrient-limited cultures, kinetic parameters are best estimated using multiple additions of the substrate and a short constant incubation time (Method 2). It appears that this method determines membrane transport, which is still not completely free of feedback inhibition even when the incubation time is very short (e.g. 2 min). The short incubation time is necessary because the maximal uptake velocity (V,) decreases with increasing incubation time especially for phosphate and ammonium. Method 3 provides valuable information on a third parameter, V,, the approximate assimilation rate of the limiting nutrient, that is not obtained by the other methods. Multlple sequential additions of the limiting nutrient to N-or Si-limited Skeletonema costaturn and Chaetoceros debilis revealed that if the additions were small (e.g. 2 pM NH,), there was no change in subsequently determined nutrient uptake kinetic parameters. If the sequential additions were larger (e.g. 6 PM) then the maximal uptake rate slowed with time.

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Section: Ecological Implicationsmentioning

confidence: 99%

Determination of nutrient uptake kinetic parameters: a comparison of methods

Harrison¹,

Parslow²,

Conway³

1989

Mar. Ecol. Prog. Ser.

163

132

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“…Ammonium production (ammonljication) that creates dilution in isotope concentration during incubation Ammonification may influence N flux measurements by underestimating uptake because of isotope dilution of the ammonium fraction (Dugdale and Goering 1967;Harrison 1978;Glibert et al 1982). LaRoche (1983) measured isotope dilution of the NH,+ fraction during incubations in Bedford Basin.…”

Section: Discrepancies Between 14n Disappearance and 15n Uptakementioning

confidence: 99%

“…(Harrison 1983a; Lipschultz et al 1985), along with a surge of interest in the oligotrophic ocean and the need to understand the relative proportions of new and regenerated production (Dugdale and Goering 1967;Eppley and Peterson 1979) have resulted in increasing use of the 15N technique in oceanographic studies.…”

mentioning

confidence: 99%

The use of ¹⁵N to measure nitrogen uptake in eutrophic oceans; experimental considerations1,2

Dugdale

Wilkerson

1986

Limnology & Oceanography

435

279

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The use of 15N to measure the flux of nitrogen compounds has become increasingly popular as the techniques and instrumentation for stable isotope analysis have become more widely available. Questions concerning equations for calculating uptake, effect of isotope dilution (in the case of ammonium), duration of incubation, and relationship between disappearance of a nitrogen compound and the 15N uptake measurement have arisen, especially for the research conducted in oligotrophic regions. Fewer problems seem to have occurred in eutrophic areas. However, sufficient literature now exists to allow some generally accepted experimental procedures for 15N studies in eutrophic regions to be laid down.Incubation periods of 2-6 h appear to avoid problems related to isotope dilution and to overcome the bias introduced in some cases by initial high rate or surge uptake. During such incubation periods, assimilation is measured rather than uptake or transport into the cell. Incorporation of 15N into the particulate fraction is usually linear with time over the periods currently used. The 15N method provides a better estimate of incorporation into phytoplankton than 14N disappearance, but a small fraction appears to be lost. Although most workers suggest the loss to be a result of dissolved organic nitrogen production, direct evidence is lacking.If the considerations discussed here are applied with the lSN techniques currently available, reliable estimates of phytoplankton nitrogen flux in eutrophic areas can be obtained.Although the 15N technique was introduced into studies of the nitrogen cycle in the sea 25 years ago (Dugdale et al. 196 l), its use has been confined to a relatively small number of laboratories, primarily to make estimates of phytoplankton uptake of inorganic nitrogen. Usually mass spectrometers have been used to obtain 15N : 14N isotope ratios. Improved instrumentation l This study was supported by National Science Foundation grants OCE 77-27006 for the CUEA studies and OCE 82-l 5221 and OCE 85-05400 for the OPUS program.2 Contribution 4 14 of the Allan Hancock Foundation. (Harrison 1983a;Lipschultz et al. 1985), along with a surge of interest in the oligotrophic ocean and the need to understand the relative proportions of new and regenerated production (Dugdale and Goering 1967; Eppley and Peterson 1979) have resulted in increasing use of the 15N technique in oceanographic studies.With the proliferation of laboratories using 15N in marine investigations, some disagreement has arisen over both 15N measurement techniques and the appropriate equations for calculating uptake of dissolved inorganic nitrogen (DIN). The major problems that have arisen concern the disappearance of l 5N during incubations (Laws 673

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“…Although uptake rates decreased as a hyperbolic function with time of the incubation, the decrease was most remarkable within 30 min (Wheeler et al 1982) and uptake rates were almost constant from 1 to 24 h of incubation (Harrison 1983). Therefore, estimated rates of NH 4 + uptake could be comparable among the seasons as the first order of approximation.…”

Section: Nitrogen Uptake and Regenerationmentioning

confidence: 72%

Release of dissolved organic nitrogen by a planktonic community in Akkeshi Bay

Hasegawa

Koike²,

Mukai³

2001

Aquat. Microb. Ecol.

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We applied conventional incubation experiments combined with a 15 N-tracer technique to evaluate the relative contributions of phytoplankton, micrograzers and copepods to the release of dissolved organic nitrogen (DON) or dissolved nitrogen (DN) in coastal waters from Akkeshi Bay, eastern Hokkaido, Japan. From March to November, water temperature ranged from -1 to 17°C, and chl a concentrations showed about 5-fold change (from 2.6 to 12 µg l ) greatly exceeded those of the other planktonic assemblages. DON release by micrograzers was well coupled to DON uptake by bacteria, indicating that there was a significant nitrogen flux from phytoplankton to bacteria via micrograzers. DON supply in the upper layer would activate microbial food webs and consequently relieve the short supply of dissolved inorganic nitrogen for phytoplankton during the stratified season. KEY WORDS: DON · 15 N-tracer · PlanktonResale or republication not permitted without written consent of the publisher Aquat Microb Ecol 24: 99-107, 2001 by phytoplankton, micrograzers, and copepods at a subarctic embayment and (2) to discuss the role of DON in coastal marine nitrogen flux. Our results showed that the rates of DON release by micrograzers greatly exceeded those of the other planktonic assemblages, and the DON they supply in the upper layer would be important for relieving the short supply of dissolved inorganic nitrogen (DIN) available to primary producers. MATERIALS AND METHODSAkkeshi Bay is located on the eastern Pacific coast of Hokkaido, Japan. All samplings were done at a fixed station (water depth 13 m: 43°01' N, 144°52' E) in the bay. Temperature and salinity were measured using a YSI salinometer (Model 33 S-C-T meter) at 1 m intervals from the surface to a depth of 12 m. In this study, we defined organisms that passed through a 94 µm net as microplankton. Because 91 to 100% of chlorophyll a (chl a) in whole seawater was contained in the < 94 µm fraction (Hasegawa unpubl.), our results represented the majority of phytoplankton activity. However, micrograzers' activity on nitrogen flux might be underestimated, since the general definition of micrograzer was < 200 µm (Sieburth et al. 1978).Incubation experiments (< 94 µm assemblage). Incubation experiments with size-fractionated seawater (< 94 µm) were carried out on 9 March, 25 May, 29 June, 24 August, and 10 November 1998. Conditions of incubation are shown in Table 1. NH 4 + regeneration rates were determined by the 15 N-isotope dilution method (Blackburn 1979, Caperon et al. 1979) and NH 4 + uptake rates were determined after . Further, DO 15 N release was measured on 25 May, 29 June and 24 August 1998 and expressed as percent extracellular release (PER: percentage of 15 N-labeled DON to 15 N-labeled DON plus 15 N-labeled particulate organic nitrogen [PON], Hasegawa et al. 2000c). Details of the methods used to measure DON release are described in Hasegawa et al. (2000a,c).The dilution method with 15 N-tracer. DON release rates mediated by micrograzers were estimated b...

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The time‐course of uptake of inorganic and organic nitrogen compounds by phytoplankton from the Eastern Canadian Arctic: A comparison with temperate and tropical populations

Cited by 34 publications

References 11 publications

Determination of nutrient uptake kinetic parameters: a comparison of methods

Determination of nutrient uptake kinetic parameters: a comparison of methods

The use of ¹⁵N to measure nitrogen uptake in eutrophic oceans; experimental considerations1,2

Release of dissolved organic nitrogen by a planktonic community in Akkeshi Bay

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The time‐course of uptake of inorganic and organic nitrogen compounds by phytoplankton from the Eastern Canadian Arctic: A comparison with temperate and tropical populations

Cited by 34 publications

References 11 publications

Determination of nutrient uptake kinetic parameters: a comparison of methods

Determination of nutrient uptake kinetic parameters: a comparison of methods

The use of 15N to measure nitrogen uptake in eutrophic oceans; experimental considerations1,2

Release of dissolved organic nitrogen by a planktonic community in Akkeshi Bay

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The use of ¹⁵N to measure nitrogen uptake in eutrophic oceans; experimental considerations1,2