48 U. S. BUREAU OF FISHERIES 



Physiological experiments consisted of studies of the eti'ects of 

 l^iilp mill effluents on the respiration and feeding of oysters. Con- 

 tinuous records of the pumping activity of oysters show marked 

 reductions in the amount of water pumped in concentrations of 1 

 part per thousand or stronger of liquor from the diffuser building. 



Studies employing the carmine cone and drop counting methods 

 of measuring the ciliary activity of oysters showed that very dilute 

 concentrations of the effluent from the diffuser building brought 

 about depression in ciliary motion. In some instances concentra- 

 tions as low as 1 part in 4,000 of tlie effluent in sea water reduced 

 the rate of flow after exposure of 2 to 4 hours. 



Using the drop counting method additional experiments were per- 

 formed at Woods Hole, Mass. Employing the oysters and sea water 

 •of this region results were obtained showing reductions in rate of 

 pumping Avhen diffuser building liquor was added to the water sup- 

 plied to the oysters. The reductions observed were similar to those 

 found at Yorktown with the oysters and sea water of that region. 

 It was also found from tests at Solomons Island, Md., and Beaufort, 

 ^. C, that the reductions in rate of flow of water through the oysters 

 caused by the addition of pulp mill effluents were essentially the same 

 as in the exi^eriments carried on at Yorktown. These experiments 

 were completed by the carmine cone technique. 



Comparative studies of the physiological effects of the three main 

 sewer outlets of the pulp and paper mill at West Point on oysters 

 :show that the most toxic is the effl,uent from the diffuser building; 

 the next place is occupied by the paper mill effluent, while the dis- 

 charge of the sludge pond is least toxic. 



Tests with dried and ashed effluent of the diffuser building indicate 

 that the material causing reduction in the rate of pumping by oysters 

 is organic, for drying at low temperature and then redissolving in 

 water materially decreases its toxicity. It was indicated by a series 

 of experiments that aeration of the effluent for a month did not appre- 

 ciably alter its toxicity. This is of particular interest since ponding 

 of the effluent for slow oxidation is the plan of a new pulp mill being 

 put into operation at Franklin, Va., in its endeavor to render the 

 waste nontoxic to aquatic life. 



The effects on oysters of fractions of the effluent and pure com- 

 pounds known to occur in pulp mill wastes were tested to determine 

 the active material of the effluent. Incomplete results indicate that 

 the turpentine condensate resulting from the recovery of turpentine 

 from the liquor is not particularly toxic to the oyster, nor was pure 

 phenol under the experimental conditions employed. Observations on 

 phenol salts, resins, and soaps are being continued. 



Field and laboratory investigations have demonstrated that pulp 

 jmill effl[uent is toxic to oysters and that its discharge into the York 

 Eiver is primarily responsible for the decline of the oyster industry 

 in this area. 



Studies on the sporozoan parasite of the oyster. — Studies on the 

 :sporozoan parasite of the oyster whicli is very generally distributed 

 in coastal regions from Maryland and Virginia to Louisiana were 

 continued by Dr. H. F. Prytherch at Beaufort, N. C. Spores of this 

 parasite were found in the tissues of the muscle, gills, and mantle, 

 the number per oyster frequently amounting to several million. The 



