or 24 drops = 100 ml. of raw water. One 

 drop, therefore, equals 16, 8 or 4 ml. of 

 raw water, approximately. A 25 mm. 

 square No. 1 cover glass is used, and 

 with the usual lOx oculars and lOx or 

 43x objectives in the microscope there 

 are 16 or 64 paths--not circular fields, 

 but paths--across such a cover; that is, 

 in one drop of catch. If a drop of 

 catch =16 ml. of raw water, obviously- 

 one path at lOOx (lOx oculars and lOx 

 objective) equals one ml. of raw water 

 and at 430x one path equals 1/4 ml. 

 Using the mechanical stage, one counts 

 two paths across each drop on a slide, 

 bisecting the cover and at right angles 

 to each other. This usually compensates 

 for inequality of distribution beneath 

 the cover, and often enables one to 

 identify much smaller organisms than 

 can be identified in a counting chamber. 

 The method is fast and easy, and the 

 amount of error is small. The number 

 of paths counted depends to some ex- 

 tent on the accuracy desired. Common 

 practice has been to count eight paths 

 (two paths for each of four drops), 

 which at 430x usually equals two mis. 

 of raw water. G^. brevis is not always 

 certainly identified at lOOx, but is un- 

 mistakable at 430x. [p. 8.] 



". . . The 1952 outbreak was appar- 

 ently rather linnited in the area affected, 

 which seemed to center around Sanibel 

 Island. There is little published infor- 

 mation on this outbreak, at least at the 

 present time. . . . [p. 11.] 



"The first brevis to appear in 1953 

 were found in samples taken in Lemon 

 Bay fronn the bridge on August 19, and 

 in Sarasota Bay at the Cortez bridge, 

 August 26. The first of these was a 

 preserved sannple, containing 1 16 brevis 

 per ml. and the second a living sample, 

 showing 178 per ml. On the latter date, 

 August 26, there were no brevis at 

 Naples or at Piney Point. On September 1 

 the organism appeared at the Placida 

 Ferry wharf, and on September 3 there 

 were 1,732 per ml. in Big Sarasota Bay, 

 about three miles north of the bridge, 

 and 600 per ml. in the surf at Golden 

 Beach on Longboat Key. They were also 

 present as far out as 22 miles off Anna 

 Maria, and on this date dead fish were 

 appearing. It is significant that no dead 

 fish were seen, or at least reported, 

 until after the populations of brevis had 

 attained considerable numbers, [p. 11,] 



"Such was the beginning of the 1953- 

 54 Red Tide. From the very first it was 

 marked by local concentrations rather 

 than a widespread uniform distribution. 



The area covered was very large, and 

 brevis was found in samples taken as 

 far north as Tarpon Springs and as far 

 south as Big Marco Pass, a distance of 

 175 miles, and from land-locked waters 

 such as Lemon Bay to 45 miles off- 

 shore. A sample network for an area 

 this size was not possible, despite the 

 efforts of the three research organiza- 

 tions at work and those of the Gulf Coast 

 Coordinating Committee. In the event 

 of another outbreak, some such set-up 

 to assess the magnitude of the invasion 

 seems almost a necessity if distribution 

 is to be ascertained, [p. 11.] 



"At the north and south ends of the 

 infested area there was a rather sharp 

 tapering off of brevis populations. No 

 fish kills were reported from Tarpon 

 Springs or Big Marco Pass, although 

 dead fish were reported as abundant off 

 Anclote Key on at least two occasions. 

 These may well have been carried there 

 by the northbound current of the eddy 

 reported by Hela (11). Out in the Gulf, 

 the most westerly reported occurrences 

 of brevis were about 140 miles south- 

 west of Fort Myers in samples taken by 

 the U.S. Coast and Geodetic Survey ship 

 'Hydrographer.' At the time of this 

 writing some of the offshore Gulf 

 still awaiting analysis, 

 diminution in numbers 

 along the western edge of the shaded 

 area (Figure 1) indicates that the area 

 of intense growth is fairly well delimited, 



[p. 11.] 



"Clearwater had a single small fish 

 kill along its beaches, with some attend- 

 ant discomfort; Naples had a rather 

 larger one. The beaches between these 

 two points, from Fort Myers Beach to 

 the Pinellas county beaches, all had one 

 or more very heavy fish kills, and the 

 inhabitants were subject to a great deal 

 of discomfort. Probably the most con- 

 tinuously affected area was from Casey 

 Key to Sanibel, and the heaviest con- 

 tinuous infestation was in the Boca 

 Grande area. [p. 11-12.] 



samples are 

 However, the 



". . . one cannot detect a discolora- 

 tion of the water at the surface until 

 the number of brevis exceeds 250,000 

 or more per liter. . . . 



"Frequently, samples taken a few 

 miles from a rather dense local swarm 

 will show no brevis at all. Examples of 

 this are easy to cite. On September 18, 

 1953, sannples taken just off Pass-a- 

 Grille had 2,444,000 per liter, while 

 there were none at John's Pass or in 

 Sarasota Bay at Cortez. Samples at the 

 latter station contained 83,200 per liter 



48 



