FIGURE 2.— Photograph of blue crab with section removed from vertically cracked carapace. 



sterile containers. The blue crab gills were ho- 

 mogenized in a blender for 2 min at high speed 

 and further prepared for bacterial analysis fol- 

 lowing the standard procedure for oysters. Blue 

 crab gills and oysters were analyzed on a wet- 

 weight basis (50 g), but sediments were analyzed 

 on a volume-to-volume basis (50 ml) because of 

 the great differences in sediment densities found 

 in the environment. The initial dilution was 

 made by volume displacement of the diluent by 

 the sediment in a calibrated container as pre- 

 viously described (Babinchak et al. 1977). All 

 dilutions were made using sterile 0.1% peptone 

 (Difco Laboratories, Detroit, Mich.) saline solu- 

 tion (1.5% NaCl). 



Total viable, aerobic, heterotrophic bacterial 

 counts for all samples were determined, using 

 the spread-plate technique and a modification of 

 a low-nutrient, artificial seawater plating med- 

 ium (ASWLN) of Litchfield et al. (1975) con- 

 taining the following ingredients per liter of 

 half-strength artificial seawater (Rila Marine 

 Mix, Teaneck, N.J.): 0.5 g peptone (Difco), 0.5 g 

 yeast extract (BBL Microbiology Systems, 



Cockeysville, Md.), 0.1 g sodium glycerophos- 

 phate (MCB Manufacturing Chemist, Inc., Cin- 

 cinnati, Ohio), and 20 g agar (BBL). Three repli- 

 cates of each dilution were plated, and the 

 inoculated plates incubated at 20°C for 14 d. 



Fecal coliform counts in all samples were esti- 

 mated by the three-tube most-probable-number 

 (MPN) procedure prescribed for seawater and 

 tissues (American Public Health Association 

 1970, 1976). Lauryl sulfate tryptose broth (BBL) 

 was used in the presumptive test, with confirma- 

 tion in EC broth (BBL) incubated at 44.5°C in a 

 circulating water bath. 



Vr6Wo-like organisms were enumerated on 

 thiosulfate citrate bile salts agar (TCBS; BBL) 

 using the spread-plate technique for all samples. 

 Fifteen to thirty colonies, representing all coloni- 

 al types, as determined with oblique or darkfield 

 illumination through a stereomicroscope, were 

 picked only from the blue crab gill-inoculated 

 TCBS plates. The cultures were purified and 

 then characterized biochemically using the API 

 20E system (Analytab Products, Inc., Plainview, 

 N.Y.). 



887 



