Biogeochemical Control of Phosphorus Cycling and Primary Production in Lake Michigan

• Published in: Limnology and oceanography Vol. 39; no. 4; pp. 961 - 968
• Main Authors: Brooks, Arthur S., Edgington, David N.
• Format: Journal Article
• Language: English
• Published: Waco, TX American Society of Limnology and Oceanography 01-06-1994
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biogeochemistry; Biological and medical sciences; Fresh water ecosystems; Freshwater; Fundamental and applied biological sciences. Psychology; Lake water; Lakes; Limnology; Marine; Natural springs; Phosphorus; Phosphorus cycle; Primary productivity; Ratios; Sediments; Synecology; Lake Michigan; Great Lakes of America; North America; America; USA, Michigan L; USA, Illinois, Michigan L; Freshwater environment; Primary productivity; Temperature; Environmental factor; Nutrient; Phosphorus; Biogeochemical cycle
• ISSN: 0024-3590; 1939-5590
• DOI: 10.4319/lo.1994.39.4.0961

A 3-yr study in Lake Michigan has shown a 27 mmol P $m^-2$ increase in the mass of total P (TP) in the water during spring when the lake is mixed from surface to sediment. This value is an order of magnitude greater than the annual P input from external sources. TP changed in concert with increases in chlorophyll a and organic N and decreases in chlorophyll a and organic N and decreases in nitrate and soluble Si. The concentration of soluble reactive $PO_4^3-$ (SRP) remained relatively constant throughout the study. We hypothesize that the SRP concentration is maintained by a chemical equilibrium with calcium-phosphate species. The increased mass of TP arises from the sequestering of P by algae which displaces the chemical equilibrium and allows more P to be released to the water from the sediments. Solar irradiance and the duration of mixing determine the magnitude of the spring bloom and the demand for P that must be supplied through the flux of P from the sediments to the overlying water.