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Sedimentary record of changes in the condition of Lake Washington
Author(s) -
Edmondson W. T.
Publication year - 1991
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1991.36.5.1031
Subject(s) - bioturbation , sediment , diatom , deposition (geology) , slumping , sedimentary rock , eutrophication , geology , phosphorus , ecology , paleontology , environmental science , oceanography , nutrient , biology , chemistry , organic chemistry
Variations with depth in properties of the sediment of Lake Washington are compared with known conditions in the lake. Annual changes of deposition form pairs of cryptic layers, dominated respectively by diatoms and mineral particles, that are revealed by X‐radiography. A period of eutrophication is recorded by sediment rich in phosphorus. Two later peaks of P can be attributed to deposition of eroded material during floods. The relative importance of diatom species changed in coordination with changes in nutrition and the presence of Oscillatoria which can suppress some species of centric diatoms by antibiosis. Experiments confirm that selective feeding by oligochetes can result in nonrandom transport of different components of sediment. Sporadic, brief outbursts of rare species of diatoms give precise dating and opportunity for measuring bioturbation under fully natural conditions by repeated sampling. Precise data on vertical distribution of diatoms are given by overlapping scanning electron micrographs of dried cores.