534 



Eisler, Ronald, and Melvin P. Weinstein. 1967. 



Changes in metal composition of the quahaug clam, Mercenaria mercenaria , 

 after exposure to insecticides. Chesapeake Sci. 8(4): 253-258. 



Adult quahaugs survived for 96 hrs when exposed to malathion concentrations 

 as high as 37,000 ppb and methoxychlor as high as 1,100 ppb. Each clam 

 regularly extended its siphon and showed its mantle edge at least once 

 daily. Behavior showed no detectable difference from that of controls. 

 Thus, hard clams are more resistant to these insecticides than many marine 

 fish and crustacean species. Clams will concentrate these substances in 

 their tissues. Quahaugs in 19 1 of seawater containing 4 ppb methoxychlor 

 accumulated residues, wet weight, of 1,300 ppb in gills and 75 ppb in 

 mantle. At concentrations of 22 to 1,100 in the medium absolute amounts of 

 methoxychlor increased, but at a greatly reduced rate. Normal outward 

 appearance and behavior of quahaugs containing whole body residues of 1,600 

 ppb methoxychlor suggests that clams may not be capable of detecting this 

 insecticide at those levels. Analysis of whole animal and selected tissues 

 showed that pesticide-exposed clams had different concentrations of certain 

 metals in their tissues than controls. Quahaugs exposed to 1,100 ppb 

 methoxychlor showed greatest differences from controls in levels of mantle 

 Zn (+42%), muscle Ca (-42%), muscle K (+36%), mantle Ca (-35%), muscle Na 

 (+32%), whole clam Ca(-31%), muscle Mg (+23%), and mantle K (+16%). The 

 greatest changes shown when exposed to malathion were in mantle Zn (+61%), 

 mantle Ca (-36%) , and muscle Ca (-29%) . Unlike clams exposed to 

 methoxychlor, those exposed to 37,000 ppb malathion contained less K in 

 mantle (-32%) than controls. Graphic profiles based on metal shifts among 

 tissues might be used to identify unfavorable environmental conditions 

 before obvious morphological or physiological changes occur. - J.L.M. 



535 



Eisler, R. , G. R. Gardner, R. J. Hennekey, G. LaRoche, D. F. Walsh, and P. P. 

 Yevich. 1972. 



Acute toxicology of sodium nitrilotriacetic acid (NTA) and NTA-containing 

 detergents to marine organisms. Water Research, Pergamon Press 6(9): 1009- 

 1027. 



Phosphates in detergents are useful water softeners, but excessive amounts 

 contribute to eutrophication of natural waters. The monohydrated sodium 

 salt of nitrilotriacetic acid (NTA) is an effective chelating agent, used 

 alone or as partial replacement for polyphosphates in heavy-duty detergents. 

 NTA is degraded only partially by activated sludge columns. Thus, discharge 

 of large quantities of NTA into the environment is a matter of concern. 

 Eleven invertebrate and fish species, including Mercenaria mercenaria , were 

 used to screen toxicity of NTA and NTA-containing syndets . Quahaug and bay 

 mussel were most resistant to sodium nitrilotriacetic acid (TL50, 168 hr 

 values) 10,000 mg/l . Quahaugs were more sensitive to syndet Ch and syndet 

 Ga. No histopathological effects were observed. NTA was most toxic at 

 comparatively low salinities. It was concluded that NTA might be hazardous 

 to marine teleosts and higher invertebrates and that additional research 

 should be done. - J.L.M. 



536 



Eissinger, Richard A. 1975. 



Progress in central California shellfish seed production. Proc. Natl. 

 Shellf. Assn. 65: 7(abstract). 



International Shellfish Enterprises, a 4-yr old company, is presently 

 expanding facilities to sell large quantities of oyster and clam seed. Clam 

 seed of 3-7 mm will be available for planting. The hatchery and nursery tank 

 farm will use warm water from a Moss Landing, Calif., power plant. - J.L.M. 



149 



