APPENDIX C 



PRELIMINARY OBSERVATION ON THROUGH- GUT TRANSPORT OF 

 SUSPENDED SOLIDS BY ESTUARINE FISH 



1. Introduction . 



The objective of this study was to determine the accumulation of par- 

 ticulate matter on the gills and in the alimentary canal of fish exposed 

 to sublethal concentrations of suspended solids. Observations were made 

 on white perch, striped bass, and hogchokers. 



2. Materials and Methods . 



The following suspended solids were used: 



(a) Kaolinite clays: 



(1) Hydrite MP, median particle size 9 micrometers. 



(2) Hydrite Flat-D, median particle size 4,5 

 micrometers. 



(3) Hydrite-10, median particle size 0.55 micrometer. 



(b) Fuller's earth, median particle size 0.50 micrometer. 



(c) Natural bottom muds taken from Long Point, Patuxent River, 

 Maryland. 



The particle-size distribution of the natural Patuxent River mud is shown 

 in Figure C-1. 



Fish were captured by otter trawl in the Patuxent River estuary and 

 transported to the laboratory in a flow-through system of river water. 

 All specimens were starved 72 to 96 hours before exposure to suspended 

 solids, and were not fed during an exposure. 



Groups of 6 to 10 fish, dependent upon size and species, were exposed 

 to graded concentrations of suspended solids for 24 hours. The gills, 

 stomach, and intestine of each individual were examined to determine the 

 accumulation of suspended solid following an exposure. 



Accumulation of solids on the gills, in the stomach, and in the intes- 

 tine was scored on a scale from (no accumulation) to 4 (continuous coat- 

 ing of particulate matter). Scoring was based on visual observation by a 

 single, trained observer. Mean accumulation fpr each group of fish exposed 

 to each concentration was plotted as a histogram. 



Replicate exposures of each species to graded concentrations of each 

 solid were not done. Data are from the preliminary observations. 



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