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S.M. Adams
base of the sucker. Thus, in this case, contaminants had an indirect effect on lipid
dynamics in fish by suppressing food availability, resulting in nutritional and fat
storage deficiencies.
Changes in salinity regimes have also been implicated in causing lipid changes
in fish. Roche et al. (1983) exposed sea dace, Dicentrarchus labrax, to salinities
ranging from 4 to 40 ppt and noted changes in total lipids and triglycerides in liver
and muscle. As salinity increased from 4 to 40 ppt, total lipids increased in both
liver and muscle. Dramatic increases were observed as salinity was raised from 4
to 18 ppt, but no increases were noted after 18 ppt. Salinity changes caused
alterations in the phospholipids, particularly phosphatidyIcholine and phosphatidylethanolamine. Thus, a hypo-osmotic medium seems to cause decreased biosynthesis of some lipid compounds in this species.
The ability of fish to tolerate increased acidification stress in aquatic systems
affected by acid rain is largely dependent on the starvation and lipid status of the
organism. Cunningham and Shuter (1986) found that starvation and low fat levels
led to progressive weakening of the osmoregulatory system, thereby reducing the
tolerance of young small mouth bass to reduced pH. Not only did starvation and
low pH have an interactive effect on total body lipid composition, but chronic
exposure to low pH tended to significantly increase metabolic costs that further
reduced lipid levels. Thus, the toxicity of reduced pH on juvenile smallmouth bass
appears to be related to the level of emaciation as expressed by lipid stores (K wain
et aI., 1984). The occurrence of starvation at the end of winter is a critical factor in
the life cycle and survival of small mouth bass in acidified systems.
Summary and Future Initiatives. Environmental stressors can alter both the quantity and quality of lipids in fish. Exposure to contaminants such as pesticides,
heavy metals, and PCBs can increase or decrease total lipids and triglycerides,
depending on the species of fish and the concentrations and duration of contaminant exposure. The decrease in lipid levels of fish experiencing many types of
stress suggests that free fatty acids are mobilized to yield extra energy for the
purpose of mitigating or ameliorating the effects of that stress. For lipophilic
contaminants, lipids can serve as a protective reservoir helping to prevent toxicants from reaching and affecting target organs. Varying thermal regimes can
affect lipid dynamics in fish by increasing metabolism, by altering foraging and
breeding behavior, or by increasing susceptibility to disease and parasites. Energy
allocation patterns in fish have also been shown to be influenced by not only
contaminants such as paper mill effluents but also by ecological factors such as
food and habitat availability. Therefore, when evaluating the effects of environmental stressors such as contaminants on lipid dynamics, the influence of other
environmental factors should also be accounted for. Although some stressors exert
direct effects on lipid dynamics in fish, other stressors such as contaminants can
have indirect effects on lipid dynamics by suppressing food availability for predatory species.
Stressors of all kinds, including natural and anthropogenic sources, have been
shown to affect lipid dynamics in various fish species. Much of what we under-
S.M. Adams
base of the sucker. Thus, in this case, contaminants had an indirect effect on lipid
dynamics in fish by suppressing food availability, resulting in nutritional and fat
storage deficiencies.
Changes in salinity regimes have also been implicated in causing lipid changes
in fish. Roche et al. (1983) exposed sea dace, Dicentrarchus labrax, to salinities
ranging from 4 to 40 ppt and noted changes in total lipids and triglycerides in liver
and muscle. As salinity increased from 4 to 40 ppt, total lipids increased in both
liver and muscle. Dramatic increases were observed as salinity was raised from 4
to 18 ppt, but no increases were noted after 18 ppt. Salinity changes caused
alterations in the phospholipids, particularly phosphatidyIcholine and phosphatidylethanolamine. Thus, a hypo-osmotic medium seems to cause decreased biosynthesis of some lipid compounds in this species.
The ability of fish to tolerate increased acidification stress in aquatic systems
affected by acid rain is largely dependent on the starvation and lipid status of the
organism. Cunningham and Shuter (1986) found that starvation and low fat levels
led to progressive weakening of the osmoregulatory system, thereby reducing the
tolerance of young small mouth bass to reduced pH. Not only did starvation and
low pH have an interactive effect on total body lipid composition, but chronic
exposure to low pH tended to significantly increase metabolic costs that further
reduced lipid levels. Thus, the toxicity of reduced pH on juvenile smallmouth bass
appears to be related to the level of emaciation as expressed by lipid stores (K wain
et aI., 1984). The occurrence of starvation at the end of winter is a critical factor in
the life cycle and survival of small mouth bass in acidified systems.
Summary and Future Initiatives. Environmental stressors can alter both the quantity and quality of lipids in fish. Exposure to contaminants such as pesticides,
heavy metals, and PCBs can increase or decrease total lipids and triglycerides,
depending on the species of fish and the concentrations and duration of contaminant exposure. The decrease in lipid levels of fish experiencing many types of
stress suggests that free fatty acids are mobilized to yield extra energy for the
purpose of mitigating or ameliorating the effects of that stress. For lipophilic
contaminants, lipids can serve as a protective reservoir helping to prevent toxicants from reaching and affecting target organs. Varying thermal regimes can
affect lipid dynamics in fish by increasing metabolism, by altering foraging and
breeding behavior, or by increasing susceptibility to disease and parasites. Energy
allocation patterns in fish have also been shown to be influenced by not only
contaminants such as paper mill effluents but also by ecological factors such as
food and habitat availability. Therefore, when evaluating the effects of environmental stressors such as contaminants on lipid dynamics, the influence of other
environmental factors should also be accounted for. Although some stressors exert
direct effects on lipid dynamics in fish, other stressors such as contaminants can
have indirect effects on lipid dynamics by suppressing food availability for predatory species.
Stressors of all kinds, including natural and anthropogenic sources, have been
shown to affect lipid dynamics in various fish species. Much of what we under-