o 
> 
h- 
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if) 
32 
30 
28 
°0b8@ 
8 
o 
o 
LlI 
or 
D 
V- 
< 
q: 
LlI 
0. 
LU 
1970 1971 1972 1973 
Figure 20-2. Narrangansett Bay bottom water salinity, dissolved 
oxygen and temperature (monthly measurements at sampling 
site, V 2 mile north and southwest of site). 
NOTE: Each circle represents a single measurement made on a single day (3 
replicate measurements). 
Burrowing activities were described and quantified by observing single 
worms in sediment-filled thin aquaria (2 cm thick, 14 cm wide and 15 cm 
deep). These aquaria were maintained in flow-through systems at appropriate 
temperatures. The thin aquaria allowed free three-dimensional movement 
(worms can easily turn in 1 cm thick aquaria), yet also permitted direct 
observation of some activities with a stereomicroscope when the worms 
burrowed along the glass. The glass walls are considered to represent an 
obstacle to the worm not unlike buried rocks or bivalve shells, which are 
306 
