Experiments to determine mortality caused 

 by stimulation were inconclusive because of 

 difficulty in maintaining wornns in the labora- 

 tory. The five species tested withstood up 

 to 10 pulses per second of 250-/isec. length 

 and 35-v. field strength for as long as 1 hr, 

 with no mortality. The most sensitive species 

 of polychaete studied here died within 2 to 4 

 min. at the above rate and pulse length with 

 a field strength of 5 to 10 v. 



We have found that continued test stimulation 

 of annelids at 200-//sec., 3 pulses per second, 

 0.6 to 6.0 V. leads to lessened response and 

 finally no response. Different species lost 

 their response at different times, ranging from 



30 sec. to 7 min. The stronger pulses, which 

 produce stronger contractions, increase the 

 rate of fatigue. 



We are making similar studies on species 

 taken from an inshore shrimphabitat. Presence 

 or absence of response is being noted to permit 

 comparisons between typical species from 

 this area and those from the beach zone. 



R. W. Menzel, Project Leader 



Florida State University 

 (Contract No. 14-17-0002- 

 111) 



CHEMISTRY AND SEA-WATER LABORATORIES 



ESTUARINE WATER ANALYSIS 



The chemical analyses of estuarine water 

 samples give evidence of irregularity that we 

 think is caused by a lack of representative 

 samples. This shortcoming could be caused 

 by particulate matter, which makes these 

 waters difficult to identify chemically. Data 

 on total nitrogen and total phosphorus are 

 particularly affected. We have begun an inves- 

 tigation of sampling and analytical procedures 

 to determine whether we can do anything to 

 increase the reliability of estuarine cheinical 

 data. 



a small plug of glass wool in a funnel, the 

 copper content is reduced to 0.7 //g.at./l. or 

 by a factor of about 6. The absorption effect 

 of the wool seems to be inversely proportional 

 to the salinity of the sample. Thus, salt water 

 (S = 27 p.p.t.) with an initial copper content 

 of 3.3 //g.at. of copper per liter when sinnilarly 

 filtered has a content of 2.7. Filter paper has 

 a connparable effect. 



We are now investigating the results of 

 filtration on all of our analyses. 



RED-TIDE TOXICANTS 



TOTAL NITROGEN ANALYSIS 



The maximum number of total nitrogen 

 analyses per day has been more than doubled 

 by eliminating the need to digest the samples 

 in a fume hood. We learned that by plugging 

 the Kjeldahl digestion flasks with glass wool, 

 sulfuric-acid fumes are effectively contained 

 within the flask during digestion. Thus, the 

 operation can be carried on in the laboratory 

 proper without fear of contaminating the air 

 with noxious fumes. The use of glass wool 

 has increased our maximum daily production 

 from about 20 to over 50 analyses. 



We completed the experimental evaluation 

 of six toxicants that have been shown in previous 

 reports to be sufficiently pronnising under 

 laboratory conditions to be considered for 

 control. Final tests consisted of reestimating 

 minimum toxic levels for each of the six 

 materials in a culture of Gymnodinium breve 

 made from samples taken from a recent 

 red-tide outbreak (spring of 1963). Previous 

 work had been based on G. breve that had 

 been maintained in the laboratory since 1952. 

 In artificial medium, the newer culture of 

 G. breve seems to be less vulnerable to the 

 toxicants than the older one. In Florida-water 

 medium, however, its reaction toward the 

 toxicants is about the sanne. 



SAMPLE FILTRATION 



It is not always advisable to use a filtering 

 medium to remove particulate matter from 

 a water sample before chemical analysis. The 

 filter material can alter the composition of 

 a sample not only by removing particulate 

 matter but also by adsorbing ions from solu- 

 tion. We learned, for example, that if 180 ml. 

 of a particulate-free, fresh-water sample 

 containing 4.5 ug.at./ I (nriicrogram atoms) of 

 dissolved copper per liter is passed through 



SEA-WATER LABORATORIES 



The facilities of the sea-water laboratories 

 have been used not only by our personnel but 

 also by other research organizations. Univer- 

 sity of Texas Medical School personnel con- 

 tinue to use the sea-water laboratories for 

 work on the molecular basis of brain function 

 in fish (described in our annual report for 

 fiscal year 1964). University of Georgia per- 

 sonnel used our lagoon laboratory to study the 



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