Controlled Ecosystem Pollution Experiment (CEPEX) 



CEPEX is an international, cooperative, field research 

 project that involves trapping water and natural pelagic marine 

 communities in large plastic enclosures (10 m diameter by 23 

 m deep) and assessing the effects of selected pollutants on 

 these ecosystems. The field site is located in Saanich Inlet, 

 Vancouver Island, British Columbia. The projects in this pro- 

 gram are listed in table 5. 



Generally, all pollutants introduced to the experimental 

 containers to date show similar first effects on the organisms 

 present. Specifically, the effects of metals and petroleum on 

 bacteria are transient and short-term owing to the population's 

 rapid adaptation (about 3 days) to imposed stress. Conse- 

 quently, measurements of heterotrophic activity are probably 

 not reliable as potential indicators of pollutant stress after the 

 first few days of exposure. 



Phytoplankton also adapt to stress quickly (less than 15 

 days). In mixed populations of bacteria and phytoplankton, 

 measures of standing crop (chlorophyll, ATP, carbon) and 

 rate functions (carbon-14 and nutrient uptake kinetics, etc.) 

 provide little information on the effects of pollutants at the 

 ecosystem level. 



Some physiological measurements (respiration, excretion 

 rates) show little relation to pollution stress in zooplankton. 

 Other indices of metabolic well-being (egg production, feed- 

 ing rate) are sensitive indicators of stress at sublethal levels. 

 In general, small zooplankton, regardless of species, are more 

 sensitive than larger organisms (except jellyfish). The conse- 

 quences of pollution on higher trophic levels, for the most part, 

 remain unsolved. 



The Mercury III experiment was run in the large bags for 

 71 days during summer 1976. On day 9, mercury was added 

 to the two experimental bags at concentrations of 1 and 5 

 parts-per-billion (ppb). On three occasions (day 24, 37 and 



Large CEPEX bags in Saanich Inlet 



52), water and sediment were pumped from the bottom of 

 the bags to reseed the surface layer. Nutrients were also added 

 on day 37 and 52. During the experiment, the 1 ppb and con- 

 trol bags showed a close rephcation in dominance and abund- 

 ance of phytoplankton and zooplankton species. The centrate 

 diatoms, initially captured in all three bags, were almost gone 

 before addition of the mercury. They were replaced by flagel- 

 lates and dinoflagellates after the first and second upwelling 

 and silicoflagellates after the third upwelling. A wide variety 

 of zooplankton species was captured initially. The copepod 

 populations showed no decline and reached 40,000 to 50,000, 

 m'. The plankton predators were low in number in all bags. 



Table 5.-U.S. institutions, investigators, and projects In Controlled Ecosystem Pollution Experiment 



Institutions 



Investigators 



Projects 



University of Alaska, 

 Marine Science Institute 



University of California at San Diego, 

 Institute of Marine Resources 



University of Georgia, 



Skidaway Institute of Oceanography 



University of Miami, Rosenstiel School of 

 Marine and Atmospheric Science 



J. J. Goering and 

 A. Hattori 



J. R. Beers 



R. W. Eppley 

 W. H. Thomas 

 F. Azam 

 D. W. Menzel 



H. L.Windom 



M. R. Reeve 



Nitrogen and Silicon Regeneration in Controlled 

 Aquatic Ecosystems 



The Role of Microzooplankton in an Environmental 

 Effects Program 



Kinetics of Nutrient Assimilation by Phytoplankton 



Effects of Pollutants on Marine Phytoplankton 



Role of Bacteria in Polluted Marine Ecosystems 



Integrated Field Studies and Operations 



Heavy Metal Variations in Natural and Polluted 

 Ecosystems 



The Role of Zooplankton in an Environmental 

 Effects Program 



Woods Hole Oceanographic Institution 



G. W. Grice 



Zooplankton Population Assessment 



