ANOXIA 
by 
Dr. Jay L. Taft 
Howara University 
and 
Dr. Thomas C. Malone 
Horn Point Environmental Laboratory 
Dr. Taft: I'm very pleased to be back in this area for a 
conference on Chesapeake Bay. I am also pleased to acknowledge 
Tom Malone as the co-presenter; but he is not responsible for 
any statements that I might make. 
Chris D'Elia has asked us to discuss anoxia in the 
Chesapeake Bay. Anoxia, in a broader context, is part of an 
oxygen gradient. Oxygen gradients are normal features of 
systems that have density gradients in the vertical. In the 
Chesapeake, the first account of possible oxygen stress was 
published in 1629 in the notes of John Smith. His party was 
travelling up one of the tributaries and observed fish swimming 
near the surface with their heads out of the water. They also 
observed dead fish along the shore. This behavior has been 
associated with oxygen stress or with advective processes 
carrying organisms into the shallows. In modern accounts, both 
fish and crabs have been observed to behave in the same fashion 
producing "jubilees" along the shore, presumably an escape 
response to low oxygen water being advected into the shallows. 
The first account I have found explaining the mechanism for 
forming oxygen gradients in estuaries was written by Sales and 
Skinner, in the Journal of the Franklin Institute in 1917, from 
data collected in the Potomac River Estuary and in the Upper 
Chesapeake Bay in 1912. They write, "...this phenomenon is 
caused by the stratification of the water due to the specific 
gravity of the under-run of sea-water, which cuts off vertical 
circulation, and to the subsequent depletion of the oxygen in 
the lower layers by natural agencies." The "natural agencies" 
involved were respiration of plants and animals, direct 
oxidation of dead organic matter, and the decomposition which 
results from the action of bacteria. Newcombe, working out of 
the Chesapeake Biological Laboratory in the late 1930's and 
early 1940’s, further documented the observations made by Sales 
and Skinner. In an article in Science , July 22, 1938, Newcombe 
and Horne write, "Studies on the physical and chemical 
properties of Chesapeake Bay waters during the summer of 1936 
gave evidence of a definite oxygen-poor layer at the bottom in 
deeper regions, and data from subsequent series of water samples 
have proved the existence of that layer and have furnished 
interesting information concerning its vertical and horzontal 
extent". 
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