44
3. Toxic Effects of Selenium in Fish
podocytes, endothelial and tubular cells, and both capillary and central veins (which collect and transport urine). The livers of Belews
Lake green sunfish that had accumulated high levels of selenium
showed focal intracapillary proliferative glomerulonephritis (Sorensen
et al. 1984). In this condition, excessive numbers of mesangial cells
are present along with an abnormally abundant matrix and
periglomerular fibrosis (which can lead to a hardening of the tissue).
Numerous tubular casts were present, and tubular epithelium was
desquamated, vacuolated, and often destroyed (which can render the
tubular system of the mesonephros incapable of functioning properly).
These renal changes in Belews Lake fish were consistent with symptoms of chronic selenium poisoning in other vertebrates (Sorensen et
al. 1984).
Heart
A clear pathological pattern occurred in the hearts of fish from Belews
Lake. The pericardial spaces surrounding the heart were filled with
inflamatory cells which were not present in fish from reference locations. This condition was diagnosed as severe pericarditis. Numerous
inflamatory cells were also present within the ventricular myocardial
tissue, a condition known as myocarditis. The occurrence of pericarditis and myocarditis was attributed to the direct action of selenium on
heart tissue, coupled with indirect effects of selenium on the kidney
(ie, selenium-induced glomerulonephritis and associated uremia)
(Sorensen et al. 1984).
Ovary
Ovaries of fish from Belews Lake contained numerous swollen, necrotic, and ruptured mature egg follicles, especially in gravid individuals. No such pathology was observed in fish from reference
locations (Sorensen et al. 1984). These toxic symptoms were primary
factors contributing to reproductive failure of fish in Belews Lake. Nineteen species were affected, and the aquatic ecosystem was severely
altered for over a decade (Lemly 1985, 1997).
Eyes
One of the lesser known symptoms of selenium poisoning in fish is
the occurrence of selenium-induced cataracts. This condition, which
can affect both the lens and cornea, has been induced experimentally
in mammals by dietary exposure to selenite (Shearer et al. 1987). Numerous fish from Belews Lake had corneal cataracts on their eyes
3. Toxic Effects of Selenium in Fish
podocytes, endothelial and tubular cells, and both capillary and central veins (which collect and transport urine). The livers of Belews
Lake green sunfish that had accumulated high levels of selenium
showed focal intracapillary proliferative glomerulonephritis (Sorensen
et al. 1984). In this condition, excessive numbers of mesangial cells
are present along with an abnormally abundant matrix and
periglomerular fibrosis (which can lead to a hardening of the tissue).
Numerous tubular casts were present, and tubular epithelium was
desquamated, vacuolated, and often destroyed (which can render the
tubular system of the mesonephros incapable of functioning properly).
These renal changes in Belews Lake fish were consistent with symptoms of chronic selenium poisoning in other vertebrates (Sorensen et
al. 1984).
Heart
A clear pathological pattern occurred in the hearts of fish from Belews
Lake. The pericardial spaces surrounding the heart were filled with
inflamatory cells which were not present in fish from reference locations. This condition was diagnosed as severe pericarditis. Numerous
inflamatory cells were also present within the ventricular myocardial
tissue, a condition known as myocarditis. The occurrence of pericarditis and myocarditis was attributed to the direct action of selenium on
heart tissue, coupled with indirect effects of selenium on the kidney
(ie, selenium-induced glomerulonephritis and associated uremia)
(Sorensen et al. 1984).
Ovary
Ovaries of fish from Belews Lake contained numerous swollen, necrotic, and ruptured mature egg follicles, especially in gravid individuals. No such pathology was observed in fish from reference
locations (Sorensen et al. 1984). These toxic symptoms were primary
factors contributing to reproductive failure of fish in Belews Lake. Nineteen species were affected, and the aquatic ecosystem was severely
altered for over a decade (Lemly 1985, 1997).
Eyes
One of the lesser known symptoms of selenium poisoning in fish is
the occurrence of selenium-induced cataracts. This condition, which
can affect both the lens and cornea, has been induced experimentally
in mammals by dietary exposure to selenite (Shearer et al. 1987). Numerous fish from Belews Lake had corneal cataracts on their eyes