Organization: University of California 



Scripps Institution of Oceanography 

 Investigator: William H. Thomas, Osmund HolmHansen, and 



Farooq Azam 

 Project title: Effects of Polutants on Marine Phytoplankton 



and Bacterial Communities (CEPEX) 

 Grant No.: GX-39139 



Field work with quarter-scale CEEs commenced in 1973 

 with replication and sampling experiments. The biological 

 events in four CEEs replicated well in May 1974. Effects of 

 Cu on natural algal communities at Scripps (winter 1974) 

 showed that crops and photosynthesis were decreased at about 

 10 ppb Cu. Cu in CEEs inhibited algal crops and photosyn- 

 thesis and bacteria activities initially but both populations 

 recovered after one month incubation. The dominant algae 

 changed, so that microflagelates were more abundant in Cu- 

 treated CEEs, while diatoms were abundant in control CEEs. 

 Resistance to Cu was found in the bacterial population after 

 prolonged inhibition and Cu-treated bacteria were also Hg- 

 resistant. The elemental and gross chemical composition of the 

 microbial crop did not change as a result of Cu treatment. ATP 

 levels followed the phytoplankton crop changes. Cu/ATP ratios 

 did not change which indicated that algal cells were not killed 

 but that Cu was algistatic. Hydrocarbons added to CEEs caused 

 an initial increase in the algal crop and photosynthesis but this 

 was not a strong effect. Bacteria were inhibited by petroleum 

 hydrocarbons and did not develop resistance to them. Inhibition 

 depended on the concentration and type of hydrocarbon. In 

 small scale experiments Hg inhibited a dinoflagellate crop at 

 about 1-5 ppb. 



Organization: University of Miami, Rosenstiel School 



of Marine and Atmospheric Science 

 Investigator: M. R. Reeve 

 Project title: The Role of Zooplankton in an Environmental 



Effects Program (CEPEX) 

 Grant No.: GX-39140 



Short-term (24 hours) L. D. 50 concentrations for mer- 

 cury and copper were determined for a variety of zooplankton. 

 For a single species, and amongst species, L. D. 50 concentra- 

 tions were inversely proportional to size, with mercury some 

 2 to 4 times more toxic than copper. These data suggest that 

 the critical effects of a toxicant will be manifested on the young- 

 est stages of any species and possibly its eggs, and in the trophic 

 sense at the microzooplankton level of the food chain. Offshore 

 species of copepods were slightly more sensitive than inshore 

 zooplankton (for the same size) with the exception that a 

 ctcniiphorc was the most sensitive organism tested for its size. 

 The least sensitive species on this basis was a rotifer. During 

 the two copper experiments at Saanich, significant sub-lethal 

 effects on the feeding, respiration and phosphorous excretion of 

 a variety of zooplankton were demonstrated after exposure to 

 copper concentrations as low as 5 ppb, even when the organ- 

 isms did not show any mortality during the course of the ex- 

 periment. The CEEs were shown to permit conditions far more 

 natural than laboratory environments for the maintenance of 

 natural zooplankton populations. Growth and egg-production 

 occurred in the CEEs as well as photoplankton control by herbi- 

 vore grazing and hervibore control by carnivores. 



Organization: Woods Hole Oceanographic Institution 

 Investigator: G. D. Grice 



Project title: Zooplankton Population Assessment (CEPEX) 

 Grant No.: IDO740515 



As part of the CEPEX program, this investigator is cur- 

 rently analyzing the results of three experiments conducted 

 from April to October 1974 at the CEPEX site at Saanich 

 Inlet, B. C: a replication study and two copper experiments 

 in which Cu (as CuSO') was introduced to produce concen- 

 trations of 10 and 50 ppb and 5 and 10 ppb, respectively. The 

 studies were performed in polyethylene cyclinders (CEEs), each 

 containing approximately 66 m' of seawater. 



The replication experiment was designed to assess the pre- 

 cision and accuracy with which zooplankton population abun- 

 dance could be estimated within a CEE. Two sampling devices 

 were tested: a 20-cm modified Bongo net (202 /im) for col- 

 lecting integrated samples from 14 m to the surface, and a 

 Schindler trap for obtaining discrete samples from 14 m, 7 m, 

 and just below the surface. Samples from these two devices 

 were compared with samples collected by pumping all of the 

 water from the CEE through a 202 /j.m net. Statistical analysis 

 of the samples showed that both Bongo and Schindler samplers 

 provide an acceptable level of precision and accuracy for the 

 determination of population size and fluctuations. It was con- 

 cluded that Bongo collections are the best means of estimating 

 zooplankton densities in a CEE. while the Schindler trap can 

 be used to investigate vertical distribution and other aspects of 

 plankton patchiness. 



Analysis of samples from the first copper experiment has 

 recently been completed. Total counts show that the zooplank- 

 ton in control CEEs declined during the month-long experi- 

 ment, probably as a result of grazing by ctenophores and me- 

 dusae. Zooplankton decrease in the two experimental (10, 50 

 ppb copper) CEEs was, however, significantly more rapid than 

 in the control CEEs. The effect was more pronounced in the 

 CEE with the addition of 50 ppb Cu than in the one with an 

 addition of 10 ppb. 



Diversity indices were computed for all samples, but no sig- 

 nificant trends were evident, despite both a marked decline in 

 total numbers and changes in speces dominance. Samples were 

 also compared by similarity index. A dendrogram constructed 

 by cluster analysis of similarity coefficients for unweighted 

 paired samples showed that the samples are divided into two 

 groups, polluted and unpolluted. Samples from the two control 

 CEEs, and samples from the experimental enclosures prior to 

 the addition of copper are more closely related to one another 

 than to samples obtained from the experimental CEEs after the 

 addition of copper. 



Organizaion: Woods Hole Oceanographic Institution 



Investigator: Ralph F. Vaccaro 



Project title: The Complementary Role of Heterotrophic 



Microbial Measurements in an Environmental Effects 



Program (CEPEX) 

 Grant No.: GX-39147 



Readily available species of "C-labelled organic substrates 

 at trace concentrations are used to experimentally assess hetero- 

 trophic microbial activity. Studies are being conducted in the 



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