Other experiments used morphological, physiological, and 

 biological criteria to assess the effects on two species of clams 

 (Mercenaria mercenaria and Mya arenaria) of selected hydro- 

 carbons (pentachlorophenol, hexachlorobenzene, and benzene) 

 which are dissolved in acetone and injected into the clams. 



Histological examination by light microscopy reveals necrosis 

 and inflammation at the injection site owing to acetone dam- 

 age; test hydrocarbons have no detectable effect. Pentachloro- 

 phenol injections increase hemolymph concentrations of acid 

 phosphatase and alkaline phosphatase in both Mya and Mer- 



cenaria; hexachlorobenzene causes a slight increase in alkaline 

 phosphatase. Electrophoresis of hemolymph protein shows 

 changes in protein patterns for both clams. 



Additional effects studies using phthalate ester plasticizers, 

 a new class of marine pollutants, were made to determine 

 their toxicity to marine organisms. Moderate effects on growth, 

 development, and mortality were detected when adult killifish, 

 larval grass-shrimp, and mud crabs were exposed to phthalate 

 ester plasticizers. However, toxic effects did occur in certain 

 phytoplankton species including blue-green algae, green algae, 



2 4 6 8 10 12 14 



CONCENTRATIONS % of 20 ppm 



16 



Figure 10. — Growth of an isopod (Sphaeroma quadridentatum) in the water soluble fraction of No. 2 fuel oil. 



13 



