Rapid, storm-induced changes in the natural abundance of sup 15 N in a planktonic ecosystem, Chesapeake Bay, USA
- Harvard Univ., Cambridge, MA (United States)
- State Univ. of New York, Stony Brook (United States)
Samples of dissolved inorganic nitrogen (DIN), particulate nitrogen (PN), and two species of zooplankton were collected during two north-south transects of the Chesapeake Bay in the autumn of 1984 (27-28 September and 3-5 October). During the first transect, the natural abundance of {sup 15}N ({delta} {sup 15}N) in the major dissolved and planktonic pools of nitrogen suggested that the {delta}{sup 15}N of PN was largely determined by isotopic fractionation during uptake of NH{sub 4}{sup +} by phytoplankton. Averaged over the transect as a whole, the {delta}{sup 15}N of the herbivorous calanoid copepod Acartia tonsa was 4.1% higher than that of the PN, while the {delta}{sup 15}N of the carnivorous ctenophore Mnemiopsis leidyi was 6.4% higher than that of the PN. In the interval between the two transects, storm-induced mixing of the water column resulted in the injection of NH{sub 4}{sup +} into the surface layer of the bay. In combination with ancillary physical, chemical, and biological data, these changes in {delta}{sup 15}N provided estimates of the isotopic fractionation factor for NH{sub 4}{sup +} uptake by phytoplankton ({alpha} = 1.0065-1.0080) as well as the turnover time of nitrogen in Acartia tonsa (6.0-9.6 days). Despite the changes in {delta}{sup 15}N observed during this cruise, the relative distribution of {sup 15}N between trophic levels was preserved: during the second transect, the difference in {delta}{sup 15}N between Acartia tonsa and PN was 3.6%, and the difference in {delta}{sup 15}N between Mnemiopsis leidyi and PN was 7.3%. These results demonstrate that the natural abundance of {sup 15}N can change dramatically on a time scale of days, and that time-series studies of the natural abundance of {sup 15}N can be a useful complement to studies using tracer additions of {sup 15}N to document nitrogen transformations in planktonic ecosystems.
- OSTI ID:
- 7067053
- Journal Information:
- Geochimica et Cosmochimica Acta; (United States), Vol. 55:12; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
Similar Records
Collection and cultivation methods of Acartia tonsa for toxicity testing
Experimental records of the effect of food patchiness and predation on egg production of Acartia tonsa
Related Subjects
CHESAPEAKE BAY
NITROGEN CYCLE
NITROGEN 15
ECOLOGICAL CONCENTRATION
AMMONIUM COMPOUNDS
AQUATIC ECOSYSTEMS
CHEMICAL COMPOSITION
CRUSTACEANS
FLUCTUATIONS
ISOTOPE RATIO
NITROGEN
PLANKTON
QUANTITY RATIO
SEAWATER
STORMS
TRACER TECHNIQUES
UPTAKE
WATER CHEMISTRY
ANIMALS
AQUATIC ORGANISMS
ARTHROPODS
ATLANTIC OCEAN
BAYS
CHEMISTRY
COASTAL WATERS
DISASTERS
ECOSYSTEMS
ELEMENTS
HYDROGEN COMPOUNDS
INVERTEBRATES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
NITROGEN ISOTOPES
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
OXYGEN COMPOUNDS
SEAS
STABLE ISOTOPES
SURFACE WATERS
VARIATIONS
WATER
540310* - Environment
Aquatic- Basic Studies- (1990-)