STUDIES IN MARINE ECOLOGY. 171 



so that they can be bridged. Strong tidal currents run through 

 them the greater part of the day. They are relatively shallow, 

 rock-walled channels, containing about six feet of water and are 

 connected with open water by creeks which are also rock edged. 

 Small patches of mud and sand occur frequently and the whole 

 system of protected waterways supports many plants, Asco- 

 phyllum, Fucus and Sargassum filipendula. 



Hadley Harbor Flats, Northwest Gutter. — Northwest Gutter 

 separates Uncatena Island from Naushon. Before opening into 

 Buzzards Bay it enlarges to form an approximately square 

 expanse of shallow water about 250 yards along the south and 

 west sides and about 400 yards in greatest diagonal. In most 

 places the water is so shallow that it is difficult to push a boat 

 along at low water. The sand bar over the channel of the 

 gutter is fully bare at extreme low tide often to the extent of an 

 acre or more. 



The wide channel is kept scoured clean by the current, but 

 behind the protecting sand and gravel spits, organic debris has 

 accumulated to the depth of several feet and supports a rank 

 plant growth composed chiefly*of eel grass. At the Bay entrance 

 there is the usual accumulation of rocks which extend off to a 

 sand bottom some four feet below the lowest tide. The mud 

 flats are bordered by rocks partially buried by mud. 



Gansett. — Gansett is an offshoot of Quamquissett Harbor and 

 has the same opening into Buzzards Bay. The main axis 

 extends at an angle from the opening so that the back portion is 

 usually protected from the direct drive of the waves. The 

 opening is about 200 yards wide and the bay is approximately 

 twice that length. At mid-mouth at mean low tide the water is 

 18 feet deep. The sides slope in rapidly near the shore so that 

 there are only narrow strips of the different habitat zones. At 

 the sides are the customary rocks and the outer corners are 

 guarded by rock piles. At the head of the bay the shore is 

 sand mixed first with gravel and lower with mud. Eel grass 

 comes within two rods of the water's edge at low tide and thickly 

 covers the bottom throughout its extent. 



North Falmouth. — The collecting grounds here are scattered. 

 They are located at the head of Cataumet Harbor and extend 



