Chemical analysis has shown that various components of oils can accumulate within marine invertebrates. Several mechanisms by which this may occur have been conjectured. This paper offers experimental verification of a mechanism by which a commercially important bivalve. Mya arenaria, can accumulate oil within its tissues. The paper also documents the behavioral response of Mya arenenaria and deleterious ecological side effects resulting from oil accumulation.

Young Mya (25–35 mm) were exposed to #2 fuel oil and an oil soluble dye (Oil Red 0) which were ultrasonically emulsified in water. The concentrations tested were 50 ppm, 100 ppm and 150 ppm. Exposures were done in both natural and artificial seawater at 4°C and 22°C. Exposure periods ranged from 3 hours to 4 days.

Macroscopic observations were performed to determine the effects of the dyed oil contacting the gill surfaces and the means by which the oil was either ingested or ejected. Definite patterns of response to the dyed oil were established. Essentially, the clams treat oil micelles and globules as food or detritus particles. The smallest oil micelles are passed by ciliary currents directly to the stomach. Larger globules are bound by mucus secreted by the gill ctenidia. Gas chromatography and mass spectrometry confirmed the binding of oil-mucus. The oil-mucus is ingested or rejected by means of the clam ciliary pathways. Implications of the oil-mucus mechanism and the ejection of this mucus into the environment are discussed.

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