LETHAL EFFECTS OF SUSPENDED SEDIMENTS ON ESTUARINE FISH 
by 
J.M. O'Connor, D.A. Newnann, and J.A. Sherk, Jr. 
I. INTRODUCTION 
Previous reports on the lethal effects of suspended particulate matter 
on estuarine fish have dealt with fine particles of commerical prepara- 
tions such as kaolinite or fuller's earth (Rogers, 1969; Sherk and 
O'Connor, 1971; Sherk, O'Connor, and Neumann, 1972; Sherk, O'Connor, and 
Neumann, 1976), or with suspensions of fine particles of varied and 
undetermined compositions such as incinerator fly ash (Rogers, 1969). 
Studies of the effects of natural suspended solids on fish usually were 
concerned with growth, yield, or abundance-diversity determinations in 
natural communities (Ellis, 1936, 1937; Stickney, 1972; European Inland 
Fisheries Advisory Commission, 1964). 
The primary objective of this study was to differentiate the effects 
of suspended natural sediments from the effects of suspended mineral parti- 
cles on estuarine fish. The results of bioassay tests conducted with 
five species of estuarine fish exposed to suspensions of fuller's earth 
and resuspended natural sediments are presented (see also Sherk and 
O'Connor, 1971; Sherk, O'Connor, and Neumann, 1972; Sherk, O'Connor, and 
Neumann, 1976). 
The fish species tested in suspensions of mineral solids and natural 
sediments were: White perch (Morone americana), spot (Letostomus 
sxanthurus), menhaden (Brevoortia tyrannus), striped killifish (Fundulus 
majalts), and mummichog (F. heteroclitus). Represented within this group 
are the common littoral or shallow-water estuarine fish (striped killifish 
and mummichog), filter-feeding fish which use the estuary primarily as a 
nursery ground (menhaden), and two pelagic (open water) fish (white perch 
and spot). Fish in this range of diverse habitats and feeding habits were 
chosen to provide (a) an estimate of the range of tolerance among different 
estuarine fish exposed to highly turbid waters, and (b) the differing 
effects of fine commercial, industrial, or natural particles on typical 
estuarine fish. 
II. MATERIALS AND METHODS 
1. General. 
The lethal effects of suspended solids on fish were determined by 
static bioassay test procedures. Test groups were simultaneously exposed 
to four different concentrations of suspended solids and one group was a 
control (no added suspended solids). Particle concentration varied, 
depending upon the species tested and the duration of the test (12, 18, 
20, 24, and 48 hours). 
