572 



Water quality requireTnents for plants 



We must be careful to concern ourselves with the plants as well as 

 the animals present in the marine environment. Environmental, chem- 

 ical, and physical requirements of important species of inshore and 

 estuarine phytoplankton should be determined with reference to the 

 major cations (sodium, potassium, calcium, magnesium), minor ca- 

 tions (I manganese, molybdenum, zinc, vanadium, cobalt, copper, iron, 

 strontium), anions (chlorine, boron, fluorine, iodine nitrogen phos- 

 phorous, silicon, carbonate, ammonium, sulphate, sulphite, sulphide, 

 bicarbonate nitrite, and nitrate) , vitamins (B12, biotin, thiamin) , light 

 (photo-period, intensity, spectral distribution), temperature (ranges, 

 optimum, rate of change), pH (range, optimum, rate of pH change 

 adaptation), and eH (ranges, optimum, and rate of eH change 

 adaptation). 



Determination of the amount and chemical identification of nat- 

 urally occurring antimetabolites present in sea water and determina- 

 tion of their effects upon the abundance and distribution of important 

 phytoplankton species should be made. Information so derived could 

 be very useful for managing water quality that would inhibit unde- 

 sirable organisms. 



Water quality requirements for recreation 



Water quality research should not be dominated by concern for fish 

 and shellfish alone but should also give a major consideraiton of water 

 quality requirements for the preservation of esthetic and recreational 

 uses of the estuarine and near-shore areas. The need for intensive re- 

 search on water quality requirements for recreation is directly related 

 to the optimum recreational carrying capacity of the estuarine area. 

 This is particularly true for the effect of multiple pollutants acting 

 at the same time in the same location. Consideration should also be 

 given to public health implications ; for example, the present coliform 

 criteria for oyster production areas is higlily questionable in the light 

 of present knowledge on bacterial regrowth and the relationship of 

 this indicator organism to the probable presence of disease-producing 

 organisms. 



The need for nonJia-rmful discharges 



Waste water quality criteria should be developed to assure that the 

 discharge of waste to natural receiving waters results in a neutral 

 or beneficial effect upon the biota of the receiving waters. Many estua- 

 rine animals are capable of ingesting and eliminating heavy metals 

 without harm when these elements occur in natural ratios. 



Artificially induced imbalances, however, can result in ingestion 

 rates exceeding elimination causing accumulation of heavy metals in 

 the tissues. For example, in long-term bioassay tests, severe oyster 

 mortalities occurred due to minute amounts of chromium, nickel, and 

 molybdenum originating from a stainless steel water intake line. The 

 gradual increase of heavy metals and other trace elements over back- 

 ground values are an outstanding example of a subtle kind of ecolog- 

 ical change in our estuaries. Tliere are many sources of metallic con- 

 tamination, some of which are known, others not even suspected. One 

 wonders, for example, about the quantity of heavy metals originating 

 from the use of water in households. There are many miles of copper 



