Toxic Effects of Hydrogen Sulfide to
Juvenile Fish and Fish Eggs
LLOYD L. SMITH, JR., Professor
DONAVON M. OSEID, Associate Scientist
Department of Entomology, Fisheries, and Wildlife
University of Minnesota
St. Paul, Minnesota
INTRODUCTION
The importance of hydrogen sulfide in polluted and natural waters has been
underestimated in the evaluation of suitable water quality for aquatic organisms.
Because it has a short half life in the presence of oxygen and instrumentation has
been inadequate, it has not been detected in many environmental situations where it
is important in limiting fish occurrance or production. Lethal levels of H2S often
occur near the soil-water interface where organic material is undergoing decomposition and where early life stages of fish and aquatic insects must be passed. The
decomposable materials may be from either domestic or industrial sources and decaying plant material in unpolluted waters may also produce H2S levels detrimental to
fish production.
Colby and Smith (1) showed that high concentrations (0.02 - 0.20 ppm) of
H2S occurred within 1 to 20 millimeters of the bottom in a Minnesota river when
they were undetectable above these strata. Such concentrations occurred at all seasons. Similarly Adelman (2) has shown lethal levels of H2S in northern pike rearing
ponds near the mud-water interface. Smith and Kramer (3) and Colby and Smith (1)
showed that walleye pike eggs (Stizostedion vitreum vitreum) could not survive when
placed on a river bottom where H2S was known to be evolved, but at the same
location eggs suspended 12 in. above the bottom survived in normal numbers.
The demonstrated occurrance of H2S and low fish-egg survival led to the series
of short term bioassays (96 hr) on fish eggs, fry, and juveniles reported here. These
studies were conducted at the University of Minnesota and were supported in part by
the National Institute of Health and the Federal Water Pollution Control Agency.
TEST CONDITIONS
All tests were conducted in apparatus adapted from the short term bioassay
equipment developed by Colby and Smith (1). Test chambers consisted of acrylic
cylinders with nylon screens placed to support eggs near the bottom inlet or in 4 in.
X 4 in. X 1 in. plastic boxes in which eggs were supported on nylon screens so that
test water flowed around them at a rate of 300 ml/min. The hydrogen sulfide
solution was passed over the eggs within 60 to 100 sec after the gas was introduced
to oxygen free water and immediately after it was mixed with oxygenated water.
Determination of H2S content made at both inlet and outlet to chambers showed no
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