Table 10. Experimental and control liver glycogen 

 concentrations of hogchokers exposed for 

 5 days in 1.24 g 1"-^ fuller's earth. -^ 



Group 



Individuals 

 CNo.} 



Glycogen 

 Cmg 100 mg"^) 



Experimental 



10 



10.772 

 ±3.2 



Control 



10 



15.17 

 ±3.6 



■"■Mean values are expressed ± standard deviation. 

 2p < 0.01 (t = 2.889, d.f. = 18). 



Rates of glycogen mobilization in fish may be used to estimate the 

 energy utilization rate during starvation (Prosser and Brown, 1961; Kamra, 

 1966; Beamish, 1968; Swallow and Fleming, 1969). Thus, one interpretation 

 of the rapid glycogen utilization in hogchokers exposed to suspended sedi- 

 ments is that the sediment stress resulted in an increased energy require- 

 ment. Several observations support this hypothesis. Hogchokers have a 

 daily activity rhythm that persists in the laboratory (O'Connor, 1972). 

 Those exposed to fuller's earth did not restrict their activity to specific 

 parts of the daily cycle as did control fish. Therefore, an increase in 

 locomotor activity may account for an increase in energy utilization during 

 exposure to fuller's earth suspensions. 



Fish in fuller's earth suspensions may use more reserve energy for 

 compensatory hematological responses. Hogchokers exposed to suspended 

 solids showed evidence of significant alterations in basic hematological 

 parameters (Section II), indicating an increase in the oxygen exchange 

 capacity of the blood. Compensatory physiological alterations demand 

 energy which must come from existing internal storage during starvation. 



V. EFFECTS OF SUSPENDED SOLIDS ON RESPIRATION OF ESTUARINE FISH 



1 . Introduction . "^ 



The gills of fish are in constant contact with water. Water flowing 

 across the gill surface helps supply the oxygen necessary for metabolism. 

 Any materials dissolved or suspended in the water may come in contact with 

 the gill surfaces. 



This section assesses the effects of suspended solids on oxygen con- 

 sumption of estuarine fish. Fuller's earth suspensions were used to test 

 the particle effects of clean clay. Patuxent River sediment suspensions 

 were used to test the effects of naturally occurring particulate matter 

 and associated substances on fish respiration. 



28 



