shallow appended inlets may be completely within the photic zone. This 
coupled with the annual variation in solar radiation at 47° N and the in¬ 
famous cloud cover associated with our region causes seasonality in plant 
growth as well as fostering one type of marine plant life over another. 
The main deep channels have only small areas of sea floor within the 
photic zone. This coupled with minimal presence of hard stable rock sub¬ 
strates limits the overall abundance of macrophytes and rooted higher 
plants. Instead primary production on which the food webs are built is 
principally supplied by phytoplankton. In the shallow inlets both phyto¬ 
plankton and benthic plants are important if suitable substrate is 
present. 
The shallow appended inlets of Puget Sound have characteristic patterns of 
changing properties that are similar to those found in the shallow tem¬ 
perate zone estuaries of the east coast of the United States. A dissimi¬ 
larity is that many of our shallow inlets do not have extensive areas of 
adjacent low-lying land to form bordering marshlands. Further, our 
shallow inlets for the most part do not have large streams or rivers at 
their heads. This, coupled with being dead end arms of water, reduces 
the ability of these inlets to exchange water with the main body of the 
Sound and diminishes their tidal currents and turbulent mixing. 
The reduced advective and diffusive exchanges allow in situ changes in 
these appended embayments to play an important role in their observed 
changes in water properties. Large annual changes in water temperature 
are common due to surface heating and cooling, and if small streams are 
present, surface salinities can vary widely with stream flow (Fig. 2). 
Figure 2. Variation in surface salinity and temperature over the annual 
cycle of a shallow inlet station, Shelton, and a main basin station. 
Point Jefferson. 
40 
O 30 
O 
o 
>- 
5 20 
c 
00 
10 
0 
0 10 20 30 
TEMPERATURE, °C 
Jan ¥ 
Sejt 
Oft 
Jdii. ^ z 
/ 
/ 
Dec*'' , 
June 
ULla 
Jan.^' 
Fel 
-SHE 
- POI 
ETON 
NT JEFFER 
SON 
4 
