VI-121 



People tend to regard the irregularly flooded marsh as exoendable, 

 and the pressures for modification of this habitat raoidly are 

 becoming greater. More data is needed in this area in order to 

 make informed decisions as to whether or not we can sacrifice large 

 acreage of the irregularly flooded marsh. One of the most active 

 programs in these areas has been ditching and draining for mosquito 

 control. There is considerable disagreement as to the impact and 

 value of this kind of activity; it can be argued that it is benefi- 

 cial - while others feel that it is detrimental. Probably a case 

 can be made for both ooints. 



Bottom Sediment - Water Interface 



The bottom sediments represent an important element in the balan- 

 cing of the marine community and must be included in any considera- 

 tion of estuarine management. Disturbing these sediments by 

 dredging or by the working of bottom animals such as worm and fish, 

 can reintroduce materials which have become associated with the 

 bottom sediments into the water mass. Heavy metals, pesticides, 

 herbicides, nutrients, oil residues, and many industrial chemical 

 mixtures are examples of the kinds of materials which become 

 incorporated into the bottom. For example, lead is found pre- 

 sent in almost all types of deposits in amounts varying from 70 

 to 580 parts per million on a dry mud basis. Most of this lead 

 comes from atmospheric pollution which has passed through the 



