Phosphorus and nitrogen limitation of primary production in a simulated estuarine gradient

The transition between phosphorus limitation of primary production in freshwater and nitrogen limitation in seawater was examined along an estuarine gradient simulated in 4 large 13 m" enclosures connected in a series and containing pelagic and benthic subsystems. Nominal salinities of 0, 5, 10 and 25 ppt were maintained by exchanging appropriate volumes of water between enclosures. Klver water, which served as a freshwater endmember, was naturally high in N relative to P, while the oceanic endmember (water from Narragansett Bay, RI, USA) was low in N relative to P. Production in the water column was supported by external inputs and recycled nutrients. Bioassays, inorganic nutrient concentrations and N:P ratios of the seston and inorganic nutrients indicated that phosphorus was limiting at 0, 5 and 10 ppt, while nitrogen was limiting at 25 ppt. Coincident with this shift in limiting nutrient was a shift in the N:P ratio of nutrient supply from greater than the Redfield ratio of 16 to less than 16. External inputs established relative rates of supply in each enclosure. The relative proportion of N and P in external inputs was largely a function of the hydrodynamic mixing of fresh (high N, low P) and salt water (low N, high P) endmembers. At the scale of the estuarine segment or enclosure, neither recycled inputs from the benthos and water column, nitrogen fixation nor internal losses of N and P to sedimentation and/or denitrification materially altered relative supply rates, despite a hydrodynamic residence time of 27 d.

[1]  S. Goodgal,et al.  Sorption reactions and some ecological implications , 1954 .

[2]  H. Jitts.  The Absorption of Phosphate by Estuarine Bottom Deposits , 1959 .

[3]  F. A. Richards,et al.  The influence of organisms on the composition of sea-water , 1963 .

[4]  C. M. Grant,et al.  THE EXCHANGE OF PHOSPHATE BETWEEN ESTUARINE WATER AND SEDIMENTS1 , 1965 .

[5]  C. Lorenzen,et al.  A method for the continuous measurement of in vivo chlorophyll concentration , 1966 .

[6]  R. Burris,et al.  In situ studies on N2 fixation using the acetylene reduction technique. , 1967, Proceedings of the National Academy of Sciences of the United States of America.

[7]  J. Ryther,et al.  Nitrogen, Phosphorus, and Eutrophication in the Coastal Marine Environment , 1971, Science.

[8]  D. Schindler,et al.  Eutrophication and Recovery in Experimental Lakes: Implications for Lake Management , 1974, Science.

[9]  E. Sholkovitz,et al.  Flocculation of dissolved organic and inorganic matter during the mixing of river water and seawater , 1976 .

[10]  D. Schindler.  Evolution of phosphorus limitation in lakes. , 1977, Science.

[11]  J. C. Goldman,et al.  Growth rate influence on the chemical composition of phytoplankton in oceanic waters , 1979, Nature.

[12]  C. Officer.  Box Models Revisited , 1980 .

[13]  C. Officer,et al.  The Possible Importance of Silicon in Marine Eutrophication , 1980 .

[14]  Richard W. Ramette,et al.  Chemical equilibrium and analysis , 1981 .

[15]  J. Valderrama,et al.  The simultaneous analysis of total nitrogen and total phosphorus in natural waters , 1981 .

[16]  M. Bender,et al.  The marine phosphorus cycle , 1982 .

[17]  C. Hunt,et al.  Remobilization of Metals from Polluted Marine Sediments , 1983 .

[18]  S. V. Smith.  Phosphorus versus nitrogen limitation in the marine environment1 , 1984 .

[19]  S. Seitzinger,et al.  Denitrification and nitrous oxide production in a coastal marine ecosystem1 , 1984 .

[20]  E. Klos,et al.  Physical, chemical and biological responses to simulated wind and tidal mixing in experimental marine ecosystems , 1985 .

[21]  W. Kemp,et al.  Nutrient regeneration and oxygen consumption by sediments along an estuarine salinity gradient , 1985 .

[22]  D. Schindler,et al.  A Radiotracer Study of Phosphorus Cycling in a Eutrophic Canadian Shield Lake, Lake 227, Northwestern Ontario , 1986 .

[23]  W. Boynton,et al.  Nutrient Enrichment Studies in a Coastal Plain Estuary: Phytoplankton Growth in Large-Scale, Continuous Cultures , 1986 .

[24]  S. Wofsy,et al.  The chemical control of soluble phosphorus in the Amazon estuary , 1986 .

[25]  C. Oviatt,et al.  A comparison of system (02 and C02) and C-14 measurements of metabolism in estuarine mesocosms , 1986 .

[26]  P. Doering,et al.  Effect of the hard clam Mercenaria mercenaria on benthic fluxes of inorganic nutrients and gases , 1987 .

[27]  C. Oviatt,et al.  Fate and effects of sewage sludge in the coastal marine environment: A mesocosm experiment , 1987 .

[28]  S. Carpenter,et al.  Zooplankton‐mediated transitions between N‐ and P‐limited algal growth1 , 1988 .

[29]  R. Howarth,et al.  Nitrogen fixation in freshwater, estuarine, and marine ecosystems. 1. Rates and importance1 , 1988 .

[30]  R. Howarth,et al.  Nitrogen fixation in freshwater, estuarine, and marine ecosystems. 2. Biogeochemical controls1 , 1988 .

[31]  S. Seitzinger.  Denitrification in freshwater and coastal marine ecosystems: Ecological and geochemical significance , 1988 .

[32]  L. Ward,et al.  Phytoplankton, nutrients, and turbidity in the Chesapeake, Delaware, and Hudson estuaries , 1988 .

[33]  P. Froelich.  Kinetic control of dissolved phosphate in natural rivers and estuaries: A primer on the phosphate buffer mechanism1 , 1988 .

[34]  R. Howarth.  Nutrient Limitation of Net Primary Production in Marine Ecosystems , 1988 .

[35]  R. Hecky,et al.  Nutrient limitation of phytoplankton in freshwater and marine environments: A review of recent evidence on the effects of enrichment1 , 1988 .

[36]  G. Likens,et al.  Evidence for sulphate-controlled phosphorus release from sediments of aquatic systems , 1989, Nature.

[37]  On the contribution of the benthos to pelagic production , 1989 .

[38]  A. Keller,et al.  EFFECTS OF NUTRIENT ENRICHMENT ON NATURAL POPULATIONS OF THE BROWN TIDE PHYTOPLANKTON AUREOCOCCUS ANOPHAGEFFERENS (CHRYSOPHYCEAE) 1 , 1989 .

[39]  G. Likens,et al.  A comparison of phosphorus immobilization in sediments of freshwater and coastal marine systems , 1990 .

[40]  R. Howarth,et al.  Nitrogen-fixing cyanobacteria in the plankton of lakes and estuaries : a reply to the comment by Smith , 1990 .

[41]  C. Oviatt,et al.  Are estuaries traps for anthropogenic nutrients? Evidence from estuarine mesocosms , 1990 .

[42]  Robert W. Howarth,et al.  Nitrogen limitation on land and in the sea: How can it occur? , 1991 .

[43]  M. Krom,et al.  Phosphorus limitation of primary productivity in the eastern Mediterranean Sea , 1991 .

[44]  S. Seitzinger,et al.  The effect of salinity on ammonium sorption in aquatic sediments: Implications for benthic nutrient recycling , 1991 .

[45]  Stephen V. Smith.  Stoichiometry of C:N:P Fluxes in Shallow-Water Marine Ecosystems , 1991 .

[46]  D. Weller,et al.  Nutrients and chlorophyll at the interface of a watershed and an estuary , 1991 .

[47]  R. Magnien,et al.  External nutrient sources, internal nutrient pools, and phytoplankton production in Chesapeake Bay , 1992 .

[48]  P. Harrison,et al.  A note of caution on reduction conditions when using the cadmium-copper column for nitrate determinations in aquatic environments of varying salinities , 1992 .

[49]  D. Schindler,et al.  Modification of the N : P ratio in lakes by in situ processes , 1992 .

[50]  N. Welschmeyer.  Fluorometric analysis of chlorophyll a in the presence of chlorophyll b and pheopigments , 1994 .

[51]  B. Nowicki.  The Effect of Temperature, Oxygen, Salinity, and Nutrient Enrichment on Estuarine Denitrification Rates Measured with a Modified Nitrogen Gas Flux Technique , 1994 .

[52]  P. Doering,et al.  An ecosystem level experiment on nutrient limitation in temperate coastal marine environments , 1995 .