272 



serving other coastal cities such as Ponce, Mayagiiez, Arecibo, Fajardo, 

 and Aguadilla which all have sufficient populations to create estuarine 

 pollution problems. 



The great variety of kinds of pollution and the different ways in 

 which the many components of waste materials interact with the 

 estuarine environment to damage water quality preclude the choice of 

 a single parameter to define the overall extent of water quality deg- 

 radation. Damage to water quality can be a direct and obvious thing 

 such as paper and solids from a sewage discharge (fig. IV.5.25) or 

 as subtle and invisible as the pathogenic organisms which may accom- 

 pany it. 



Table IV.5.11 lists some estuarine systems with severely degraded 

 water quality. While not exhaustive, this list shows the extent of water 

 quality degradation in many of the estuarine systems of the United 

 States, and it gives a general appreciation of the kinds of water 

 quality damage that now exist. The data in this table show only that 

 water quality degradation exists in the estuarine systems listed. In 

 many cases the data available are not sufficient to determine specific 

 sources of the pollution or how to correct it. 



DAMAGE TO ESTUARINE ECOSYSTEMS 



Pollutional damage to estuarine ecosystems may be sudden and dra- 

 matic as fish or other aquatic life forms suddenly dying, or it may be so 

 gradual as not to be noticed for many years. 



Fish kills such as those shown in figure IV.5.26 are readily apparent 

 even to the casual observer; their causes are sometimes not so easy to 

 determine. Industrial wastes appear to be responsible for the majority 

 of fish kills in 1966, the last year for which data are available, with 

 food processing being the most common industrial activity responsible. 

 The estuarine brackish and salt waters, however, had less than 1 per- 

 cent of the fish casualties reported ; probably one reason is the enor- 

 mous volume of waters available for dilution of waste discharges 

 (IV-5-11). 



The effects of physical destruction of habitat are also easy to assess, 

 at least in terms of the immediate damage caused. The more subtle 

 related effects of damage to organisms dependent indirectly on the 

 habitat for food supply are more difficult, sometimes impossible, to 

 determine. 



Many studies of different aspects of estuarine biology have been 

 made, but there are only a very few cases in which comprehensive eco- 

 logical studies have been made of pollutional effects. The available in- 

 formation on the extent of ecological damage is summarized in table 

 IV.5.12. The information base for this table is exceedingly sparse: 

 most studies were done when there was apparently some damage or 

 other kind of ecological problem. Therefore, it is not possible to say 

 whether 38 percent of the Nation's estuarine systems are undamaged 

 or merely present no identifiable problems at this time (IV-5-10). 



The estuarine systems of the Middle Atlantic biophysical region 

 have suffered the most damage; 83 percent exhibit some ecological 

 damage, but only in a few cases is the extent known in any quantifiable 

 sense. The Chesapeake Bay and Gulf of Mexico regions have the larg- 

 est numbers of heavily damaged systems, probably because of the in- 

 tensity of use of the estuarine systems in these regions. Forty percent 



