APPENDIX A 



LIVER GLYCOGEN CONCENTRATIONS IN FOUR ESTUARINE FISH 

 AND LIVER GLYCOGEN DEPLETION RATES IN WHITE PERCH 



1. Introduction . 



To derive useful data from studies of glycogen utilization in response 

 to suspended solids, several species of estuarine fish were screened and 

 "natural" liver glycogen values were established under field conditions. 

 Glycogen depletion studies were conducted to establish the expected rates 

 of glycogen mobilization in the selected species. 



Liver glycogen determinations were performed on four species: White 

 perch, striped bass, hogchokers, and spot. A glycogen depletion study 

 was conducted at two temperatures with white perch. 



2. Materials and Methods. 



Liver glycogen was determined for each of the four species within 8 

 hours of capture. Glycogen was extracted according to the method of Good, 

 Kramer, and Somogyi (1933) and quantified by the phenolsulfuric acid 

 method (Montgomery, 1957) . 



Glycogen mobilization of white perch is dependent on the breakdown of 

 glycogen (a long-chain polymer of glucose) to glucose 6-phosphate (Black, 

 Robertson, and Parker, 1961; Ingram, 1970). This enzymatic reaction is 

 highly dependent on temperature. 



Glycogen depletion in white perch was determined at 10 ± 2° and 

 20 ± 2° Celsius. On the day of capture, white perch were divided into 

 two groups of 60 fish and placed in separate holding tanks maintained at 

 either 10° or 20° Celsius by immersion in a water bath. Ten fish were 

 removed at random from each group at the initiation of the experiment and 

 after 2, 3, 7, and 8 days in the holding tanks. Liver glycogen was deter- 

 mined according to the methods previously described. 



3. Results and Interpretation . 



Mean liver glycogen values for white perch, striped bass, and spot 

 resembled one another on the day of capture (Table A-1) . Liver glycogen 

 values for hogchokers were significantly greater than those for the other 

 three species. The precision of liver glycogen determinations was satis- 

 factory in perch, bass, and hogchokers (Table A-1). In spot the variation 

 was greater; however, the standard error of the mean was only 15.5 percent 

 of the mean. These data show that levels of glycogen reserves were rela- 

 tively constant in a population. 



The rate of glycogen mobilization in starved white perch increased 

 with temperature. At 10° Celsius, glycogen stores decreased by 59.7 



59 



