815 



Heeb, M. A. 1973. 



Large molecules and chemical control of feeding behavior in the starfish 

 Asterias forbesi. Helgol. Wiss. Meeresunters. 24(1-4): 425-435. 



A. forbesi has a chemically mediated behavioral response suitable for use as 

 a bioassay in studies of chemoreception. Protein extracts from Crassostrea 

 virginica and Meroenaria meroenaria chemically induced humping reflex in 

 seastars. Extracts from clam were always more active. The highest molecular 

 weight-range fraction from clam tissue was the most active. In laboratory 

 and field tests, higher molecular weight fractions induced searching activity 

 in seastars at speeds of up to 8 cm/min. - modified author's summary - J.L.M. 



816 



Heffernan, W. Paul, and Victor J. Cabelli. 1970. 



Elimination of bacteria by the northern quahaug (Meroenaria meroenaria) : 

 Environmental parameters significant to the process. J. Fish. Res. Bd. 

 Canada 27(9): 1569-1577. 



Clams were contaminated artificially in the laboratory with Escherichia coli 

 in concentrations ranging from 10^ to 10^ cells/100 ml for accumulation 

 periods of 1 to 14 days. Clams were then transferred to seawater free of 

 E. ooli for 48 to 72 hrs. Elimination of bacteria to low residual levels 

 depended on initial E. coli content, which was a function of the organism in 

 contaminated water. Extending the contamination period from 6 hrs to 14 days 

 did not adversely affect ability of clams to cleanse themselves. After 48 

 hrs of depuration, numbers of E. coli in excess of 17 colony-forming units/100 

 g (sensitivity level of the assay method) were not found. Clams were able to 

 cleanse themselves within 48 to 72 hrs just about as well at 10°C as at 20°C. 

 At salinities 25 to 31°/oo cleansing was acceptable in 48 hrs. At 20°/°° 

 elimination was poor. Most clams closed their valves when salinity was 

 reduced to 22°/<>o. After 4 wks conditioning at 20°/°° elimination proceeded 

 equally well at salinities of 20 to 30°/oo, but not at 15°/oo. At water flow 

 rates below 13 ml/min/animal (about 1 gal/min/bu) elimination of E. coli was 

 reduced. Increasing water turbidity reduced accumulation of bacteria by 

 clams, until at 25 Jackson turbidity units of bentonite few clams could 

 accumulate to levels higher than the surrounding water. Increased turbidity 

 appeared to enhance depuration. The greater the initial contamination, the 

 longer it took to depurate to a particular level. When ambient temperature 

 of water from which clams were collected prior to contamination was less than 

 10°C elimination of E. coli was decreased. In the depuration process, 

 variability in response of individual clams must be considered. The results 

 of this study were similar to studies of elimination of poliovirus, although 

 viral elimination is less effective at temperatures below 15°C. - J.L.M. 



817 



Heffernan, W. Paul, and Victor J. Cabelli. 1971. 



The elimination of bacteria by the northern quahaug: Variability in the 

 response of individual animals and the development of criteria. Proc. Natl. 

 Shellf. Assn. 61: 102-108. 



Distributions of residual ET coliform levels in individual quahaugs after 

 depuration were dependent on initial level of contamination and on the 

 manner by which they were polluted. Higher residual levels were obtained 

 with naturally polluted clams than with those artificially contaminated with 

 E. ooli. This means that tests made with artificially contaminated clams 

 are suspect. About 1% of clams cannot be expected to reduce appreciably 

 their level of ET coliforms. Therefore, depuration should be restricted to 

 moderately polluted clams. It is possible that in heavily polluted water 

 clams deposit coliform organisms at some site which is less accessible than 

 the digestive gland to elimination of organisms via normal feeding-cleansing 

 mechanisms. This raises questions about the validity of a bacterial system 

 as an indicator of viral depuration. This needs investigation. Fifteen 

 trials showed that depuration of moderately contaminated quahaugs produced 

 a product that in terms of coliform organisms was as good or better than 

 that currently accepted from certified grounds. - J.L.M. 



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