Sedimentary records of accelerated nutrient loading in Florida lakes.

Edward S. Deevey, Michael W. Binford, Mark B. Thomas, Thomas J. Whitmore

Research output: Contribution to journalArticlepeer-review

Abstract

Transfer functions relating trophic state (Carlson's TSI chlorophyll-a ) to present day accumulation rate of (1) nutrients, (2) cations, and (3) organic sediment, are computed using Binford's 210 Pb-dilution method. As computed from surficial sediments of 27 lakes, former trophic states are reconstructed for recent ( 210 Pb-dated) sedimentary histories of 14 lakes. Of the three kinds of models potentially available, model (3) (TSI vs. organic accumulation) is the weakest statistically, and may be unduly influenced by exceptional deposition and/or preservation of allochthonous organic matter. At present, however, it is the only model applicable to all 14 of the histories tested. Results are encouraging in that model accurately predicts observed TSI's in several mesotrophic and eutrophic lakes. Clearly significant increases (accelerations) are inferred only for a of the most eutrophic lakes of the set, while the model consistently overpredicts TSI's of the 7 most oligotrophic lakes. As Whitmore's diatom-assemblage index is a better predictor of TSI than is model (3) in the one eutrophic lake in which it has been tested, we expect more persuasive results when models (1) and (2) can be tested within a more complete set of analytical data. We were surprised to find 3 severely disturbed lakes among the 12 that show little or no acceleration in rate of eutrophication in recent decades, but we defer attempts at explanation until former nutrient loading can be tested by model (1).

Original languageAmerican English
JournalDefault journal
StatePublished - Jan 1 1986

Keywords

  • Paleolimnology
  • Eutrophication
  • 210Pb transfer functions
  • Florida lakes

Disciplines

  • Biology

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