EFFECTS OF NO. 2 HEATING OIL 



ON FILTRATION RATE OF BLUE MUSSELS, 



MYTILUS EDULIS LINNE 



J. G. Gonzalez, D. Everich, J. Hyland, and B. D. Melzian 



U.S. Environmental Protection Agency 



Environmental Research Laboratory 



Narragansett, Rhode Island 02882 



ABSTRACT 



Reductions in gill filtration rates were observed for adult blue mussels, 

 Mytilus edulis, that were exposed in a continuous flow-through dosing system, 

 to three concentrations of the water-accommodated fraction of No. 2 fuel oil. 

 The oil concentrations were measured routinely by infrared spectrometry, and 

 averaged 0.019 ppm, 0.06 ppm, and 0.64 ppm throughout the exposure period. 

 Filtering rates for healthy, unexposed mussels ranged from 7.2 to 30.9 ml/min, 

 depending on ambient water conditions. In comparison to controls, filtering 

 rates decreased as the oil concentration increased, with significant reductions 

 occurring at all dose levels within 48 hours of exposure. Continued oil 

 exposure up to two weeks produced progressively higher reductions in filtering 

 rate. When returned to uncontaminated water for two weeks, the mussels 

 resumed their normal feeding rates, revealing that the effect was reversible. 

 Mussels collected from a small oil spill site exhibited similar responses. 



INTRODUCTION 



Bivalve mollusks are of considerable value to ecologists studying the effects 

 of pollution, because many of the species are sedentary filter feeders, and are 

 likely to accumulate contaminants from their surroundings. Mytilus edulis, the 



blue mussel, has become one of the most widely studied members of the group 

 since it has a worldwide distribution; it is easy to maintain in the laboratory; 

 and it is exploited commercially, particularly in European countries. Also, 

 Mytilus, because of its intertidal existence, is particularly vulnerable to oil 

 exposure. 



Several investigators have demonstrated a reduced feeding rate in mollusks 

 exposed to environmental stress. Galtsoff et al (3) reported fifty percent 

 reduction in gill ventilation rate of oysters exposed to an extract of crude oil. 



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