h 2 o 
AIR INPUT INFLOW FOOD INPUT 
h 2 o OUTFLOW 
AIRSTONE 
WATER 
CURRENTS 
PETRIE DISH COVER 
SPRING 
WATER LEVEL 
GLASS OUTER SLEEVE 
GLASS INNER SLEEVE 
NYLON MESH 
SILASTIC TUBING 
CLAMP 
Figure 14-1. The 2 8 Flow-Through Beaker System. 
NOTE: Designed by Dr. W. B. Vernberg under E.P.A. Grant R 802071 and 
modified for use in the culture of larval and juvenile Palaemonetes vulgaris. 
All surviving juvenile P. vulgaris (about 140) were transferred on day 22 
(post hatch) to the 20 8 “hatching jar”“ commonly used in hatching and 
rearing larval fish (Figure 14-2). This 30 cm diameter, clear acrylic tank, was 
modified from the manufacturer’s design by placing a 400 jum nylon mesh 
across the outflow ramp, thereby eliminating the need for a mesh over the top 
of the entire system. This smaller outflow area effectively decreased the 
chances of impinging larvae on the mesh. Gentle aeration and a water flow of 
50 ml/min created a satisfactory circulation pattern. This hatching jar system 
“Midland Plastics Co., Brookfield, Wl. 
208 
