PLANKTON AND NUISANCE CONDITIONS IN SURFACE WATER 57 



planktonic or that they interfere with both bathing and boating as effec- 

 tively as a bloom of Anabaena or Microcystis. 



Tastes and odors in drinking water are only too familiar to water 

 plant operators, as are shortened filter runs. Almost any group of algae 

 may cause them, but blue-greens, brown flagellates (such as Synura or 

 Uroglenopsis) and diatoms are the chief offenders. Increased operating 

 costs accrue in such cases, but equally bad is the loss of revenue when 

 summer cottagers leave because an onshore wind piles their beach with a 

 loathsome mass of decaying algae. And according to newspaper and other 

 reports (Staff, Univ. Miami Marine Laboratory 1947) the recent red 

 waters near the Florida shores were simply a huge bloom of dinoflagellates 

 which not only hurt commercial fishing, but also left fish carcasses along 

 shore in such numbers as to cause vacationists to leave. 



It has been observed frequently that stock will not drink while a 

 heavy red bloom of Euglena sanguinea is present. Stock deaths have been 

 attributed to poisonous blooms in the U. S. (Fitch et al. 1934), Africa 

 and Australia; and in 1946 (Hervey) waterfowl deaths in Utah were 

 ascribed to huge numbers of dinoflagellates. Mussel poisoning along the 

 Pacific Coast is familiar, and its appearance along the Atlantic Coast should 

 be carefully watched for, as we increase the species of shellfish we eat. 

 There are numerous instances of enteric diseases in man, apparently water- 

 borne, and not satisfactorily accounted for, but which seem to travel down- 

 stream — in one instance, at least, paralleling the downstream travel of an 

 algal bloom. 



The Nature, Occurrence and Causes of These Blooms 



Blooms are typical of shallow lakes in the late summer, but may occur 

 in almost any body of water at any time of the year. They are not gen- 

 erally noticed by laymen until surface waters are obviously discolored. 

 Blue-green algae are perhaps the most common producers of blooms in 

 stagnant water, but in streams a much wider variety of organisms is en- 

 countered in bloom densities. Colors range from a rather pale yellow- 

 green or blue-green, such as caused by Anabaena in Prospect Park lake in 

 Brooklyn, in 1924, to yellow (Gleotrichia, Mendota, 1942) , brown (Peridi- 

 nium, Chillicothe, Ohio, 1936), or red, Euglena sanguinea. North Alabama, 

 1935; Azolla, North Mississippi, 1940). Table I shows the organism groups 

 which reached bloom proportions (i.e., 500 organisms per ml of raw water) 

 (Lackey 1943-44), a total of 509 times during a two years' survey of 16 

 southeastern Wisconsin lakes and three rivers in 1942-43. It should be 

 clearly understood that not all this impressive list of 509 blooms were of 

 the nuisance type. 



There were actually more blooms, 509, than the 478 samplings. Evi- 

 dently high populations in Monona, Waubesa, Kegonsa, Wingra, Geneva, 

 and the three rivers were mixtures of two or more species and their normal 

 biota was rich and varied. Except Geneva, all had nuisance conditions. 

 Blooms in Geneva were due largely to very small organisms; the layman 



