7. Role of Lipids in Fish Populations
153
stand, however, about lipid response to specific stressors such as contaminants is
derived from controlled laboratory or microcosm studies in which a single stressor
is usually involved. In nature, however, fish may experience simultaneously a
variety of stressors such as various types of contaminants, fluctuating temperature
or hydrologic regimes, or variations in food or habitat availability. All these
factors, individually or in concert, can influence the health and lipid dynamics of
fish. Studies are needed, therefore, that focus on the incremental role or contribution of influential ecological factors in altering lipid dynamics in fish. For example, even if fish are exposed to high levels of contaminants in a field situation,
factors such as food availability and competition can both modulate or exacerbate
the influence of the stressor of concern. Studies are needed that address the
influence of multiple stressors on lipid dynamics of fish and how available energy
is partitioned within the organism under different types of stressors such as
organic contaminants, heavy metals, and temperature. Within this context, it is
important to distinguish between the direct effects of environmental stress on fish
that can be realized through metabolic pathways and the indirect effects of
stressors that can be mediated through the food chain affecting the quality and
quantity of energy available to consumer species. In addition, research effort
should be directed toward determining causal relationships between stress responses in fish at the lower levels of biological organization (i.e., biochemical/
physiological) and lipid storage and dynamics (i.e., Fig. 7.2). Although more
efforts have focused on this aspect of establishing causal relationships between
stress and fish health, additional studies are necessary to refine our understanding
of the relationship between seasonal levels of lipid reserves and ecological significant responses such as reproductive performance and population success. Just as
knowledge of critical lipid levels is needed to help define the success of overwinter survival and reproductive performance, a better understanding of the influence
of stressors on critical lipid levels in relation to increased susceptibility to disease,
predation, and reduced foraging ability is also needed. Environmental stressors
that alter the quality (i.e., phospholipids and cell membrane integrity) or quantity
of lipids weaken fish, render them more susceptible to disease and predation, and
also decrease behavioral and reproductive performance. In summary, understanding the lipid dynamics of fish as influenced by different types and levels of
environmental stressors should help provide effective environmental regulation
and management guidelines for maintaining healthy and successful fish populations in various types of aquatic ecosystems.
Acknowledgment. This chapter is publication 4671, Environmental Sciences
Division, ORNL.
References
Adams, S.M. Status and use of bioindicators for evaluating effects of chronic stress on fish.
Am. Fish. Soc. Sym. 8: 1-8; 1990.
Adams, S.M.; DeAngelis, D.L. Indirect effects of early bass-shad interactions on predator
153
stand, however, about lipid response to specific stressors such as contaminants is
derived from controlled laboratory or microcosm studies in which a single stressor
is usually involved. In nature, however, fish may experience simultaneously a
variety of stressors such as various types of contaminants, fluctuating temperature
or hydrologic regimes, or variations in food or habitat availability. All these
factors, individually or in concert, can influence the health and lipid dynamics of
fish. Studies are needed, therefore, that focus on the incremental role or contribution of influential ecological factors in altering lipid dynamics in fish. For example, even if fish are exposed to high levels of contaminants in a field situation,
factors such as food availability and competition can both modulate or exacerbate
the influence of the stressor of concern. Studies are needed that address the
influence of multiple stressors on lipid dynamics of fish and how available energy
is partitioned within the organism under different types of stressors such as
organic contaminants, heavy metals, and temperature. Within this context, it is
important to distinguish between the direct effects of environmental stress on fish
that can be realized through metabolic pathways and the indirect effects of
stressors that can be mediated through the food chain affecting the quality and
quantity of energy available to consumer species. In addition, research effort
should be directed toward determining causal relationships between stress responses in fish at the lower levels of biological organization (i.e., biochemical/
physiological) and lipid storage and dynamics (i.e., Fig. 7.2). Although more
efforts have focused on this aspect of establishing causal relationships between
stress and fish health, additional studies are necessary to refine our understanding
of the relationship between seasonal levels of lipid reserves and ecological significant responses such as reproductive performance and population success. Just as
knowledge of critical lipid levels is needed to help define the success of overwinter survival and reproductive performance, a better understanding of the influence
of stressors on critical lipid levels in relation to increased susceptibility to disease,
predation, and reduced foraging ability is also needed. Environmental stressors
that alter the quality (i.e., phospholipids and cell membrane integrity) or quantity
of lipids weaken fish, render them more susceptible to disease and predation, and
also decrease behavioral and reproductive performance. In summary, understanding the lipid dynamics of fish as influenced by different types and levels of
environmental stressors should help provide effective environmental regulation
and management guidelines for maintaining healthy and successful fish populations in various types of aquatic ecosystems.
Acknowledgment. This chapter is publication 4671, Environmental Sciences
Division, ORNL.
References
Adams, S.M. Status and use of bioindicators for evaluating effects of chronic stress on fish.
Am. Fish. Soc. Sym. 8: 1-8; 1990.
Adams, S.M.; DeAngelis, D.L. Indirect effects of early bass-shad interactions on predator