upper 10 m. of water during the April, June, 

 and August surveys (dissolved oxygen was not 

 measured in October). The deeper water had 

 lower concentrations, but we found no evidence 

 of stagnation. 



In April (fig. 10), dissolved oxygen in surface 

 waters ranged from 6.9 to 7.6 ml./l. The 

 concentrations were higher in summer (figs. 

 11 and 12) and ranged from 7.1 to 8.9 ml./l. in 

 June and 6.0 to 8.4 ml./l. in August. 



Dissolved oxygen in the deep water of Outer 

 Bay gradually decreased from spring to sum- 

 mer. Concentrations were about 5.2 ml./l. in 

 April, 3.6 ml, /I. in June, and 3.3 ml./l. in 

 August. The decrease may have been caused 

 by intrusion of water of lower oxygen content. 



Phosphate 



Concentration of phosphate was determined 

 only during the April and June surveys. In 

 April, concentrations in Outer Bay increased 

 with depth from a range of 1.0 to 1.2 //g. at./l. 

 (microgram atoms per liter) at the surface to 

 about 1.9 fig. at./l. at 75 m. Phosphate values 

 in Inner Bay ranged from 1.2 to 2.4 ^g. at./l. 

 in April, and although they also generally in- 

 creased with depth, they were variable. In June, 

 phosphate measurements were nnade at only 

 two stations, and these values were from 

 one-third to two-thirds of the April concen- 

 trations. 



Silicate 



Concentrations of silicate in April had dis- 

 tributions similar to those of phosphate. Con- 

 centrations in Outer Bay increased from the 

 range 10 to 1 1 ^ g. at./l. at the surface to about 

 25 fi g. at./l. at 75 m. The values in Inner Bay 

 were more variable than in Outer Bay and in- 

 creased with depth only near the head of the 

 basin. In June, silicate concentrations were 

 only one-half to one-tenth of their April values. 



Chlorophyll a 



The concentration of chlorophyll a in April 

 in Outer Bay ranged from 0.14 to 0.91p g./l. 

 and in Inner Bay from 0.38 to 11.47 //g./l. 

 Chlorophyll a was not nneasured in June, but a 

 few measurements were made in August; they 

 ranged from 0.18 to 0.83 fig./ 1, in Outer Bay 

 and from 0.90 to 4.62 f^g./l. in Inner Bay. On 

 both surveys the concentration of chlorophyll 

 a generally increased in a landward direction 

 fronn Outer Bay to Inner Bay. The maximum 

 concentrations were at depths of 5 or 10 m., 

 and the minimum values were at 50 m. or 

 greater. 



Transparency 



The transparency of the upper layers of 

 water generally decreased from April to 



October. The average Secchi disk readings (in 

 meters) for the four surveys were 9.0 in April, 

 4.9 in June, 6.0 in August, and 3.5 in October. 

 On all four surveys the transparency generally 

 decreased in a landward direction from Behm 

 Canal to Outer Bay to Inner Bay. Average 

 Secchi disk readings for the four surveys were 

 7.0 m. in Outer Bay and 4.7 m. in Inner Bay. 



CIRCULATION 



Traitors Cove fits the definitionof a positive 

 estuary (Pritchard, 1952)--the sum of runoff 

 and precipitation is greater than the evapora- 

 tion. In this type estuary the driving force of 

 the net circulation is the hydrostatic head of 

 the entering fresh water. Being less dense than 

 sea water, the fresh water remains on the 

 surface and flows seaward. Saline water from 

 below is mixed or entrained upward into the 

 surface layer (Tully, 1958). To compensate 

 for the sea water entrained upward into the 

 low- salinity surface layer and carried sea- 

 ward, a net flow of sea water moves landward 

 at depth. The net flow pattern is two layered- - 

 seaward on the surface and landward at depth. 



The actual circulation in Traitors Cove is 

 more complicated than this simple model 

 because of the turbulence created by the con- 

 striction. This turbulence is strong enough to 

 destroy almost completely the vertical density 

 stratification of the water near it. The deep 

 water of Inner Bay is created by this process 

 and is a mixture of deep water from Outer Bay 

 and the surface low- salinity waters from both 

 Inner and Outer Bay. Normally most of the 

 low- salinity water comes from runoff. On the 

 August survey, however, under conditions of 

 low local runoff into Inner Bay, much of the 

 low-salinity water probably canne from Behm 

 Canal via Outer Bay. 



On the June survey the deep water created 

 by turbulence at the constriction did not reach 

 the bottom of Inner Bay. On that survey we 

 observed a water mass with temperature of 

 about 10.5° C. and salinity of 26.5 o/o°between 

 5 and 12 m. depth in Inner Bay. It overlay a 

 second water mass of about 8.7° C. tempera- 

 ture and 28.2 °/oo salinity (see figs. 3 and 7). 

 Probably the first water niass was formed by 

 mixing at the constriction, and its density was 

 too low to displace the older bottom water in 

 Inner Bay. 



The turbulence is created at the base of the 

 tidal falls. Because this falls reverses with 

 the tide, the turbulence is created alternately 

 in Inner and Outer Bays and mipces the water 

 near the falls to vertical homogeneity. After 

 tide reversal, runoff quickly reestablishes a 

 surface brackish layer over the mixed water. 

 This action was evident on the April and August 

 surveys, when the water in Inner Bay near the 

 constriction was vertically homogeneous on 

 high tide (after a flood) and slightly stratified 



