COUNTS OF RED TIDE ORGANISMS, Gymnodinium breve , AND ASSOCIATED 

 OCEANOGRAPHIC DATA FROM FLORIDA WEST COAST, 1954-57 



Extensive fish kills have occurred 

 frequently in recent years, in the waters 

 along the southwest Florida coast, accom- 

 panied by areas of discolored water. This 

 condition, commonly known as red tide, is 

 caused by blooms of the dinof lagel late 

 Gymnodinium breve , Davis. 



Earlier outbreaks of red tide have 

 been described by Galtsoff (1948), Gunter 

 et al. (1948), Lackey and Hynes (1955), 

 Wilson and Ray (1956), and others. A 

 bibliography of red tides in Florida waters 

 was compiled by Hutton (1956). 



Since the identification of G. breve 

 in 1947, field studies have been conducted 

 by the U. S. Fish and Wildlife Service to 

 determine its incidence and distribution 

 in Gulf coastal waters and to expand exist- 

 ing knowledge of associated ecological 

 conditions. The phosphorus content of 

 these waters from May 1949 through January 



1951 has been published by the Service 

 (Graham, Amison, and Marvin 1954). This 

 was followed by a report on the oceano- 

 graphic observations from May 1949 through 

 July 1951 (Marvin 1955a). In continuation 

 of the policy of publishing original data 

 for the use of research agencies or indi- 

 viduals interested in the red tide problem, 

 this report presents in tabular form the 

 original hydrographic and biological obser- 

 vations for the period from February 1954 

 to July 1957. 



The field work was discontinued from 



1952 until it was resumed by the Service 

 in early 1954, but laboratory work on the 

 culture of G. breve was started in the 

 interim. For some results of this work 

 see Ray and Wilson (1957). 



The sampling stations (figs. 1-5) 

 extend approximately 210 miles along the 

 Florida coast chiefly in the coastal and 

 offshore waters from Clearwater to Marathon. 

 The station locations, except for some that 

 are in upstream rivers and canals, are in 

 areas in which high concentrations of G. 

 breve were found. Most stations fall with- 

 in the 10-fathom line. 



During the period covered by these 

 data there was little red tide activity. 

 The outbreak of 1952 was past, and the 

 1953-54 surgeace was on the wane in 1955; 

 from January 1955 through June 1957 no out- 

 breaks were recorded. 



METHODS 



Sampling techniques 



At the start of intensive field 

 sampling in 1954, limited information was 

 available on which to base techniques for 

 G. breve sampling. Consequently, sampling 

 equipment and methods have undergone 

 changes to conform with expanding knowledge 

 of the organism. 



Sampling was chiefly from the re- 

 search vessel Kingfish, a 43-foot, twin- 

 screw diesel cruiser, equipped with depth 

 recorder and radar. Samples have also 

 been collected with smaller boats, and a 

 seaplane was used extensively to reach 

 shallow bays and other less accessible 

 spots. Stations on canals and some at 

 beaches and rivers have been sampled from 

 the shore or bank. 



Initially, surface water samples 

 were taken with a galvanized iron bucket 

 and subsurface samples by use of a 3-liter 

 modified Kemmerer sampler. To eliminate 

 possible metallic contamination of the 

 samples a polyethylene bucket has been in 

 use since October 1954 for surface samples. 

 The subsurface sampler was replaced by a 

 weighted polyethylene container in November 

 1954. 



Immediately upon collection of a 

 sample, water temperature was measured with 

 a mercury centigrade thermometer to the 

 nearest tenth of a degree. The hydrogen 

 ion concentration was measured with either 

 a portable Coleman pH meter or a pocket- 

 size model manuf acturered by the Analytical 

 Measurement Company, Inc. 



Water samples for estimation of G. 



