150
S.M. Adams
temperatures because of warm epilimnetic water and anoxic bottom water. In
addition, lipid dynamics and recruitment success of striped bass were compromised in a thermally enriched reservoir in Virginia. In comparison with the
condition of the fish in the reference reservoir, ovary weights, condition factor,
and concentrations of vitello-triglyceride of the impacted fish were significantly
reduced in the thermal reservoir (Grimes, 1993). Results of this study suggest that
environmental stress, such as altered thermal regimes, affects the condition of
ovarian tissue possibly through the catabolism of vitelline substrates. Reproductive success and recruitment were affected by thermal conditions, which qualitatively altered profiles of vitello-compounds important in egg hatching and fry
survival.
Direct effects of increased temperature have also been reported for a variety of
species living in aquatic systems heated by power station effluents and other
industrial facilities discharging heated water to the environment. Largemouth bass
from a thermally enriched power plant cooling reservoir had lower body condition
(condition factor) and lower fat reserves than fish from unheated areas (Gibbons
et aI., 1978). From this same system, Eure and Esch (1974) found that the number
of parasites per host were significantly higher in fish from heated water sites than
in fish from cooler areas. Increased loading of parasites and other disease organisms in fish living in conditions above their range of optimal temperatures occurs
not only because such organisms are more prolific under warmer conditions but
also because the immune system of fish can be more easily compromised when
lipid levels are low (GUIT, 1983; Shul'man, 1974). Chronic malnutrition and
reduced lipid reserves, as reflected by decreased condition, were also noted by
Graham (1974) for four sunfish species residing in a power plant cooling impoundment. Total body lipids and serum triglycerides were drastically reduced in
sunfish residing downstream of an industrial complex discharging thermal
effluents and a mixture of contaminants (Adams et aI., 1992). Lower energy
reserves were attributed to increased metabolic demands due to both contaminant
exposure and thermal additions. These fish also had increased parasite loads and
infection areas (macrophage aggregates) in the liver and spleen, which were
explained by the weakened condition of the fish as a result of low energy reserves
and a compromised immune system (Rice et aI., 1996).
Temperature regimes can also affect the condition. energy dynamics, and survival of fish during their migration run. Glebe and Leggett (1981) studied depletion of energy reserves during the freshwater migration of American shad, Alosa
sapidissima. and found that the magnitude of postspawning mortality was linked
to the migratory energy demands. Shad migrating late in the run at significantly
higher temperatures expanded energy at a greater rate and thereby experienced
more extensive overall lipid depletion. Previous studies had found that 56% of the
annual variability in postspawning survival of shad was due to differences in
adverse river water temperature during the migration. Because temperature itself
was not directly lethal, the greater energy use at higher temperatures was assumed
to be an important survival regulator for this species.
S.M. Adams
temperatures because of warm epilimnetic water and anoxic bottom water. In
addition, lipid dynamics and recruitment success of striped bass were compromised in a thermally enriched reservoir in Virginia. In comparison with the
condition of the fish in the reference reservoir, ovary weights, condition factor,
and concentrations of vitello-triglyceride of the impacted fish were significantly
reduced in the thermal reservoir (Grimes, 1993). Results of this study suggest that
environmental stress, such as altered thermal regimes, affects the condition of
ovarian tissue possibly through the catabolism of vitelline substrates. Reproductive success and recruitment were affected by thermal conditions, which qualitatively altered profiles of vitello-compounds important in egg hatching and fry
survival.
Direct effects of increased temperature have also been reported for a variety of
species living in aquatic systems heated by power station effluents and other
industrial facilities discharging heated water to the environment. Largemouth bass
from a thermally enriched power plant cooling reservoir had lower body condition
(condition factor) and lower fat reserves than fish from unheated areas (Gibbons
et aI., 1978). From this same system, Eure and Esch (1974) found that the number
of parasites per host were significantly higher in fish from heated water sites than
in fish from cooler areas. Increased loading of parasites and other disease organisms in fish living in conditions above their range of optimal temperatures occurs
not only because such organisms are more prolific under warmer conditions but
also because the immune system of fish can be more easily compromised when
lipid levels are low (GUIT, 1983; Shul'man, 1974). Chronic malnutrition and
reduced lipid reserves, as reflected by decreased condition, were also noted by
Graham (1974) for four sunfish species residing in a power plant cooling impoundment. Total body lipids and serum triglycerides were drastically reduced in
sunfish residing downstream of an industrial complex discharging thermal
effluents and a mixture of contaminants (Adams et aI., 1992). Lower energy
reserves were attributed to increased metabolic demands due to both contaminant
exposure and thermal additions. These fish also had increased parasite loads and
infection areas (macrophage aggregates) in the liver and spleen, which were
explained by the weakened condition of the fish as a result of low energy reserves
and a compromised immune system (Rice et aI., 1996).
Temperature regimes can also affect the condition. energy dynamics, and survival of fish during their migration run. Glebe and Leggett (1981) studied depletion of energy reserves during the freshwater migration of American shad, Alosa
sapidissima. and found that the magnitude of postspawning mortality was linked
to the migratory energy demands. Shad migrating late in the run at significantly
higher temperatures expanded energy at a greater rate and thereby experienced
more extensive overall lipid depletion. Previous studies had found that 56% of the
annual variability in postspawning survival of shad was due to differences in
adverse river water temperature during the migration. Because temperature itself
was not directly lethal, the greater energy use at higher temperatures was assumed
to be an important survival regulator for this species.