fish also showed a significant increase in osmolality during the same time 

 period. The increased microhematocrit may reflect a concentration of 

 blood components due to loss of body water (Hall, Grdy, and Lepkovsky, 

 1926; Forster and Berglund, 1956). 



Toadfish held in 14.6 g 1"-^ of suspended natural sediment for 72 hours 

 exhibited no significant differences from a control group in hematological 

 values (Table 8). Mean hemoglobin concentrations for control and experi- 

 mental fish were 3.67 and 3.73 g 100 g"-^, respectively. Red blood cell 

 count and mean microhematocrit for experimental fish were 19.90 X 10^ 

 mra~2 and 21.67 percent, respectively. Values for control fish were 

 17.78 X 10^ mm"^ and 20.10 percent, respectively. Osmolality was 246.63 

 milliosmoles per kilogram (mOsm kg"-') for experimental fish and 251.69 

 mOsm kg"-' for control fish. 



The hematological parameters were measured in spot exposed to 14.68 

 to 16.96 g I"-' resuspended natural sediment over 7 days at 1-, 3-, and 

 7-day intervals. No significant changes in hematology were observed 

 (Table 9). 



A time-dependent study was conducted on white perch exposed to 2 g 1"-' 

 resuspended natural muds for 4-, 6-, and 14-day intervals. The mean values 

 of red blood cell count, microhematocrit, hemoglobin concentration, and 

 osmolality for experimental fish were greater than for control fish after 

 4 days of exposure, but the differences were not statistically significant 

 (0.07 > p > 0.05). Red blood cell count, microhematocrit, and hemoglobin 

 concentration of experimental fish increased after 6 days (0.05 > p > 

 0.01). Blood osmolality did not change (p > 0.5). Red blood cell count, 

 microhematocrit, hemoglobin concentration, and osmolality (0.5 > p > 0.1) 

 of the two groups were again similar after 14 days of exposure. 



Replicate experiments assessed the sublethal effects of resuspended 

 natural muds on striped bass. Studies were conducted at an arbitrary con- 

 centration because LCiqj LC50, and LCgg responses for this species were 

 not consistent. Hematological analysis revealed that exposure of striped 

 bass to concentrations of 1.5 to 6 g I"-' of natural muds for 6 days caused 

 no detectable differences between experimental and control groups. In 

 striped bass, a comparison of the effect of concentrations of 1.5 to 6 

 g 1"^ and 6 to 8 g I"-' natural mud suggested that a threshold level may 

 exist between 6 and 8 g I'-'. Below 6 g l"-*- survival is essentially 100 

 percent; no sublethal hematological effects occurred over a period of 6 

 days at 2 to 6 g I"-'. Above 6 g I"-', bass suffer mortality during 6 days 

 of exposure. 



Fish exposed to sublethal concentrations of suspended solids showed 

 the same basic hematological responses as fish deprived of sufficient 

 oxygen-- increased red blood cell count, increased hematocrit, and increased 

 hemoglobin concentration in peripheral blood. The hematological responses 

 to sublethal concentrations of suspended solids seen in white perch, 

 hogchokers, and striped killifish were similar to responses observed in 



16 



