What we have referred to as "watery fat" is a type of fatty 
tissue that has a flabby look and a semiliquid consistency. It 
appears under low magnification to be translucent and to have 
inclusions of water or other liquid free in it. This fat was 
found in both surviving and dead specimens but a significant cor¬ 
relation between it and the nonsurvivorship was noted at the con¬ 
trol station and at the sewage plant station. No mention of this 
kind of fat in the literature was found, but it was speculated 
that the presence of watery fat may be an early symptom of 
stress. In prolonged periods of high energy expenditure and 
during starvation, body fat is mobilized to act as an energy 
source. If lipids are used up, fat cells may lose their turgor 
producing this soft,gelatinous texture. 
The fact that dead fish from different stations have very 
different patterns of correlations with these factors indicates 
that there are probably multiple causes of mortality and that 
each station has its own unique combination of factors. In 
short, no single cause of mortality was found nor was it thought 
that the mortality noted in these experiments is necessarily re¬ 
lated to the cause of oyster mortality downstream. 
Crayfish Experiments 
Mortality was too low and autopsy data failed to find any 
changes which could be related to treatments. It seems that this 
species of crayfish is hardier than the golden shiners. The mor¬ 
talities occurred mostly with crayfish that had moulted and that 
were killed then by other crayfish. 
38 
