A BIOLOGICAL STUDY OF THE OFFSHORE WATERS OF 
CHESAPEAKE BAY 1 
J- 
By R. P. COWLES, Ph. D., Johns Hopkins University 
CONTENTS 
Page 
Introduction 278 
Physical features 278 
Methods 281 
Salinity 283 
Surface salinity at mouth and head-- 283 
Surface salinity from mouth to head- 285 
Variation of surface salinity across 
bay 285 
Bottom salinity at mouth and head- 288 
Bottom salinity from mouth to head- 288 
Variation of bottom salinity across 
bay 289 
Vertical distribution of salinity 289 
Salinity of water during winter 291 
Salinity of water during spring 292 
Salinity of water during summer 293 
Salinity of water during autumn 293 
Seasonal surface salinities during 
1916 294 
Seasonal surface and 30-meter salini- 
ties for Area L during 24 hours 294 
Relation of seasonal salinity to salin- 
ity of coastal water 295 
Salinity at 30 meters and averages of 
salinities 295 
Relation of direction and velocity of 
current at 24-hour stations to sea- 
sonal salinity 296 
Temperature of water 298 
Surface temperature at mouth and 
head 298 
Surface temperature from mouth to 
head 299 
Variation of surface temperature 
across bay 303 
Bottom temperature at mouth and 
head 303 
Deep-water temperature from mouth 
to head 303 
Page 
Temperature of water — Continued. 
Variation of bottom temperature 
across bay 304 
Vertical distribution of temperature- 304 
Seasonal distribution of water tem- 
perature and salinity 305 
Temperature of water during 
winter and influence of oce- 
anic water 305 
Temperature of water during 
spring 307 
Temperature of water during 
summer 308 
Temperature of water during 
fall 308 
Seasonal discontinuity of vertical 
distribution of temperatures 309 
Delay in seasonal change of temper- 
ature 310 
Bacillariophyta 1 311 
Diatoms 311 
Geographical distribution 311 
Spring and fall maxima 314 
Summer minimum 314 
Diatom counts and maximum 
and minimum salinity 315 
Diatom counts and hoinoha- 
linity 316 
Diatom counts at river mouths. 316 
Diatom scarcity at mouth of 
bay 317 
Relation of distribution of dia- 
toms to salinity 317 
Comparison of diatom counts at 
mouth and inside of bay 319 
Relation of distribution of species 
to hydrographic data 319 
Protozoa 326 
i Submitted for publication Apr. 19, 19a0. 
277 
