COPPER ORE EXPERIMENT IN A LAGOON 



155 



Salinity 



Salinity values were estimated from density- 

 temperature measurements taken with a hydrom- 

 eter calibrated to the nearest 0.2 of a salinity 

 unit (7oo) and a centigrade thermometer calibrated 

 to tlie nearest unit. 



Gymnodiniutn splendens 



Two-liter water samples for G. .splendens 

 analyses were placed under fluorescent' lights for 

 about 16 hours. This concentrated the organisms 

 in the upper part of the container. A preliminary 

 examination was made of a portion of the sample 

 taken from the meniscus. If G. splendens were 

 not observed, a zero count was assumed for the 

 sample. If in evidence, the top 200 ml., which 

 contained virtually all of the G. splendens, were 

 carefully siphoned into a flask and thoroughly 

 mixed. Ten 1 -milliliter samples were removed 

 and counted for G. splendens. The average of 

 these was converted to count per liter by multi- 

 plying by 100. An alternative method used for 

 high-count samples was similar except that the 10 

 portions were taken from the entire mixed sample. 

 The conversion to count-per-Iiter was obtained 

 by multiplying tlie average by 1,000. 



Copper 



To determine the copper concentration, we used 

 the method described by Hoste, Eeckhout, and 

 Gillis (1953). This was preferred to that of Chow 

 and Thompson (1952) because the latter method 

 is not so selective for waters of variable pH, such 

 as is found in the lagoon. Further, when coastal 

 and bay waters are aiuilyzed by tliis method, a 

 turbid extract forms occasionally that is difficult 

 to analyze. 



Zooplankton 



The zooplankton samples were obtained by 

 I)umpiiig 250 gallons of water through a plankton 

 net of \o. 2 bolting silk. These were diluted to 

 100 ml., and an aliquot part checked for tlic various 

 types of zooplankton. The count of each was 

 recorded as count per 100 liters by multiplying 

 by the appropriate factors. The size of the 

 I aliquot part varied, depending on the population 

 density of the sample. 



Barnacle setting rate 



The barnacle attachment rate was based on the 

 average daily setting-rate on 4-inch square cement 



plates suspended horizontally 2 feet below the 

 surface at each station. The rate was estimated 

 by averaging the count per square centimeter of 

 eight locations on each plate, and then dividing 

 by the number of days that the plate was sub- 

 merged in the lagoon. 



Prorocentrum sp. 



We used Wilson's (1959) dialysis membrane 

 bag method for evaluating the effects of the copper 

 ore on Prorocentrum sp. cultures suspended in the 

 lagoon. Initial and final population estinuites 

 were made by counting the organisms in several 

 0.01 ml. portions taken immediately before the 

 culture was placed in the dialysis bags and after 

 their removal from the lagoon. 



RESULTS 



Chlorophyll 



The results of the chloropliyll a, b, and c 

 analyses are shown in figure 2. We have placed 

 the November 1958 to April 1959 section of the 

 graph under the corresponding months of 1957 

 and 1958 to simplify seasonal comparison. The 

 phytoplankton blooms noted during November 

 1957 and January to March 1959 were reduced 

 during the corresponding months of 1958 and 1959. 

 Wliether or not this was an effect of the ore is not 

 known. The significant fact shown is the con- 

 tinued productivity of the lagoon after the addition 

 of ore. This is indicated by the continuation of 

 chlorophyll concentrations that are representative 

 of a highly productive area (Zein-Eldin, 1959). 



Salinity 



Figure 3 shows monthly salinity ranges and 

 averages of the lagoon. All data are based on the 

 average of station salinity values. 



Gymnodinium splendens 



The average population of G. splendens in the 

 lagoon from November 1957 to June 1959 is 

 shown ill figure 4. The November 1958 to June 

 1959 portion of the graph has been placed under 

 the corresponding months of 1957 and 1958 to 

 simplify a comparison of similar seasons. It can 

 be seen that the seasonal occurrence has not been 

 altered by the immersed ore. The January 1959 

 to April 1959 zero count cannot be considered 

 significant as far as the copper ore experiment is 

 concerned because of the subse(iuent rise that 

 followed the pattern of the previous year. 



