aquatic environment. Certainly in an area where 

 the pH is high (9.5 or above) or low (below 5.5), 

 productivity would not reach high levels due to 

 a lack of sufficient bicarbonates. 



Temperature also is an important factor in de- 

 termining the amount of growth. For each species, 

 there is an optimum range in which the greatest 

 growth occurs. 



Wave action on large expanses of water may 

 also be a factor in regulating all types of aquatic 

 plant growths. This appears contradictory to the 

 concept that winds cause mixing of surface and 

 bottom waters, thereby renewing plant nutrients 

 in the euphotic zone. However, in certain lakes 

 and reservoirs, wind-induced waves and currents 

 mechanically agitate bottom materials and waters 

 to an extent that interferes with the production of 

 phytoplankton and rooted aquatic plants. 



Various workers have discussed the concentra- 

 tions of nitrogen and phosphorus that are needed 

 for an algal bloom. Sawyer (1947) suggests that 

 a concentration of at least 1 5 fig/\ of phosphorus 

 is necessary for growth. Hutchinson (1957) states 



that Asterionella can take up phosphorus from 

 where it is present at less than one /xg/1. As a re- 

 sult of the study of 17 Wisconsin lakes, Mac- 

 kenthun (1965) cites results indicating that in- 

 organic nitrogen at 0.30 mg/1 and inorganic 

 phosphorus at 0.01 mg/1, at the start of an active 

 growing season, subsequently permitted algal 

 blooms. As yet, there is no definite information on 

 the amount of wastes that will produce predictable 

 harmful effects in a lake. There are indicators, 

 however, of developing or potentially undesirable 

 conditions. 



There are several conditions, analyses, or meas- 

 ures that will indicate eutrophication and dystro- 

 phication. Since these parameters are not infallible, 

 it is well to use them in combinations. Conditions 

 indicative of organic enrichment are: 



( 1 ) A slow overall decrease year after year in 

 the dissolved oxygen in the hypolimnion 

 as indicated by determinations made a 

 short time before the fall overturn and an 

 increase in anaerobic areas in the lower 

 portion of the hypolimnion. 



TABLE III-4. 



Chemical Composition of Some Algae From Ponds and Lakes in Southeastern 

 United States ^ 



Analysis 



Pithophora Spirogyra Spirogyra Rhizoclonium Oedogonium Mougeotis Anabaena 



Ash percent 43.4 27.77 13.06 13.86 17.36 12.69 14.54 5.19 



C percent 29.3 35.38 42.40 41.16 39.10 40.84 40.74 49.70 



N percent 2.46 2.57 3.01 2.35 3.46 2.64 1.77 9.43 



P percent 0.25 0.30 0.20 0.23 0.43 0.08 0.25 0.77 



S percent ._ 0.55 1.42 0.27 0.24 0.27 0.15 0.36 0.53 



Ca percent 8.03 3.82 0.57 0.84 0.52 0.44 1.68 0.36 



Mg percent 0.92 0.20 0.45 0.30 0.21 0.16 0.57 0.42 



K percent 2.35 3.06 0.92 0.99 1.90 3.03 1.20 1.20 



Na percent 0.13 0.07 1.42 1.43 0.09 0.06 0.49 0.18 



Fe mg/1 2,520 2,836 1,368 1,793 1,820 1,645 60 80 



Mn mg/1 2,926 829 1,641 1,658 1,687 1,729 1,080 800 



Zn mg/1 89 29 72 46 89 119 520 



Cu mg/1 19 23 47 34 75 75 143 70 



B mg/1 6.7 65 4.2 4.3 1.8 8.1 8 



Analysis 



Cladophor 



Euglena 



Hydrodictyon Microcystis 



Lyngbya 



Nitella Aphanizomenon 



Ash percent 23.38 4.12 17.94 6.2 17.20 19.11 7.21 



C percent 35.27 48.14 39.96 46.46 40.23 38.43 47.65 



N percent 2,30 5.14 3.87 8.08 5.01 2.70 8.57 



P percent 0.56 0.67 0.24 0.68 0.31 0.23 1.17 



S percent 1.58 0.19 1.41 0.27 0.28 0.34 1.18 



Ca percent 1.69 0.05 0.69 0.53 0.45 1.89 0.73 



Mg percent 0.23 0.07 0.17 0.17 0.14 0.95 0.21 



K percent 6.08 0.34 4.21 0.79 0.42 3.73 0.68 



Na percent 0.18 0.02 0.38 0.04 0.06 0.28 0.19 



Mn mg/1 1,040 240 1,373 2,751 5,230 2,388 167 



Fe mg/1 2,300 1,545 1,963 322 3,866 2,180 833 



Zn mg/1 10 73 129 48 171 240 120 



Cu mg/1 190 290 114 37 101 39 187 



B mg/1 . 84.6 3.8 ... 3.6 112 9.8 



Lawrence (personal con 



55 



