Diel periodicity of nitrogen uptake by marine phytoplankton in nitrate-rich environments

Journal Article · Sun Dec 01 00:00:00 EST 1991 · Limnology and Oceanography; (United States)

DOI:https://doi.org/10.4319/lo.1991.36.8.1689· OSTI ID:6994347

Cochlan, W P ^[1]; Harrison, P J ^[2]; Denman, K L ^[3]

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1. Scripps Institution of Oceanography, La Jolla, CA (United States)
2. Univ. of British Columbia, Vancouver (Canada)
3. Dept. of Fisheries and Oceans, Sidney, British Columbia (Canada)

It has been suggested that daily measurements of NO{sub 3}{sup {minus}} uptake by phytoplankton are indicative of the magnitude of flux of organic matter from the surface layers to the deep ocean. The authors used the {sup 15}N tracer technique to examine the magnitude of diel periodicity in the uptake of nitrogenous nutrients by microplankton in nutrient-rich environments of the oceanic subarctic Pacific and an upwelled plume off the British Columbia coast. In the subarctic Pacific, specific NO{sub 3}{sup {minus}} uptake rates, calculated at 3-h intervals for 24 h, demonstrated a clear diel pattern; average nighttime rate was about half the average daylight rate. Off British Columbia, drogued drifter buoys were used to guide repeated sampling of the euphotic zone of an upwelled plume at 6-h intervals for >48 h. Specific rates of NO{sub 3}{sup {minus}} and NH{sub 4}{sup +} uptake by phytoplankton from the near-surface and the 30% I{sub 0} light depth showed pronounced diel periodicity, whereas uptake rates of N were more or less constant over the day-night cycle at the bottom of the euphotic zone (1%I{sub 0}). The average nighttime rates of the upper waters were 15-16 and 30-36% of the NO{sub 3}{sup {minus}} and NH{sub 4}{sup +} daylight rates. The results differ from several previous diel studies in that both NO{sub 3}{sup {minus}} and NH{sub 4}{sup +} uptake demonstrated definitive diel cycles with the magnitude of periodicity in NH{sub 4}{sup +} uptake being similar to that of NO{sub 3}{sup {minus}} uptake. The authors also found that NO{sub 3}{sup {minus}}, not NH{sub 4}{sup +}, seems to be the preferred source of N during daylight, while NH{sub 4}{sup +} is preferred at night. Estimates of daily NO{sub 3}{sup {minus}} uptake rates extrapolated from short-term incubations may considerably underestimate the magnitude of the biological pump, depending on the magnitude of diel periodicity in NO{sub 3}{sup {minus}} uptake.

• OSTI ID: 6994347
• Journal Information: Limnology and Oceanography; (United States), Vol. 36:8; ISSN 0024-3590
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
29 ENERGY PLANNING
POLICY AND ECONOMY
NITRATES
ECOLOGICAL CONCENTRATION
UPTAKE
PACIFIC OCEAN
BIOGEOCHEMISTRY
PHYTOPLANKTON
PRODUCTIVITY
CARBON CYCLE
COASTAL REGIONS
DAILY VARIATIONS
ENVIRONMENTAL TRANSPORT
NITROGEN 15
NUTRIENTS
PHOTOSYNTHESIS
TRACER TECHNIQUES
UPWELLING
AQUATIC ORGANISMS
CHEMICAL REACTIONS
CHEMISTRY
GEOCHEMISTRY
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MASS TRANSFER
NITROGEN COMPOUNDS
NITROGEN ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PLANKTON
PLANTS
SEAS
STABLE ISOTOPES
SURFACE WATERS
SYNTHESIS
VARIATIONS
540320* - Environment
Aquatic- Chemicals Monitoring & Transport- (1990-)
560300 - Chemicals Metabolism & Toxicology
290301 - Energy Planning & Policy- Environment
Health
& Safety- Regional & Global Environmental Aspects- (1992-)