Marine Ecosystems under Toxic Pressure - Vulnerability of Coastal Ecosystems and Adaptation - page 23

The behavior of living organisms is susceptible to being affected
by the presence of toxic substances in the environment [WEI 01].
Disturbances in organisms' locomotive activities can lead to
deficiencies in their capacity to flee when faced with predators and an
increase in the time required to search for prey as well as
modifications in migratory activities indirectly affecting their
reproduction [TRI 97, WEI 02, WEI 04]. Several studies have also
indicated that pollutants can decrease the alimentary activity of fish.
Finally, the presence of undesirable molecules can lead to
modifications in behavior linked to reproduction (display, choice of
partner and parental care). All these behavioral changes result from
modifications in the biochemical and physiological processes on an
individual level and can have significant effects on the equilibrium of
populations and communities. In effect, the contaminants can cause
behavioral or defensive responses, which can modify biological
interactions or even intensify the effect of a contaminant.
Three general types of pollutant influence on the behavior have
been observed:
-reduced rates of predation: although numerous studies
demonstrate that ingestion or rates of predation by various animals can
be diminished by contaminants, very few identify a behavioral
mechanism associated with the hunt for food. Smith and Weis
[SMI 97], however, have stated that exposure to mercury has been
shown to correlate with a decrease in the predation intensity of the
killifish ( Fundulus heteroclitus ); Temara et al. [TEM 99] have
described changes in the predatory behavior of a starfish exposed to
soluble fractions of crude oil;
- an increased sensitivity to predation: exposure to contaminants
can inhibit a prey's specific behavior used to avoid a predator. This
effect can lead to an increase in rates of encounters between predators
and prey. As an example, Hinkle-Conn et al. [HIN 98] have found
evidence of a decrease in several species of invertebrates' capacity to
dig holes in contaminated sediments, increasing their exposure to
predators. Many other examples of increased sensitivity to predation,
triggered by a variety of contaminants, are identified in several studies