Behavioral Ecotoxicology - Ecological Biomarkers: Indicators of Ecotoxicological Effects - page 266

adaptations that occur during smolting, thereby contributing to impairments of migra-
tory behavior as shown in another species Salvelinus alpinus . This is in agreement with
the hypothesis that PCBs could be one of the factors contributing to the decline of wild
populations of Atlantic salmon as well as failures in salmon restoration (Lerner et al. 2007
and literature quoted therein). Denoël et al. (2012a) have used sets of behavioral biomark-
ers (lying, swirling, and feeding) to assess short-term effects of pesticides on frog tadpoles
( Rana temporaria ). Their results suggest that endosulfan is toxic to amphibians at environ-
mental concentrations.
Field experiments offer an additional step with a view to increasing environmental
realism. We have already discussed (Section 10.3) the method of postexposure feeding
depletion. Similar approaches were carried out to examine escape behavior in crabs Uca
pugnax exposed in the field to an oil spill (Krebs and Burns 1977) or social behavior in
fish ( Gambusia sp.) exposed to pulp and paper mill effluents including compounds with
androgenic properties (Toft et al. 2004). Another possibility is the deployment of in situ
tests to show the effects of local contamination. This strategy was able to reveal the effects
of oiled sediments on the predation rate of crabs Cancer magister on bivalves Protothaca
staminea (Pearson et al. 1981); effects of effluents on locomotion, activity phases, and feed-
ing rate of amphipod crustaceans Gammarus pulex (Gerhardt 1996; Maltby et al. 2000, 2002);
effects of contaminated sediments on feeding behavior of worms Hediste diversicolor and
crabs Carcinus maenas (Moreira et al. 2006a, b; Kalman et al. 2009; Fossi Tankoua et al. 2012);
effects of water from streams differing by their levels of chemical contaminants on swim-
ming velocity of Salmo trutta f . fario (Triebskorn et al. 1997).
10.4.2 From Individuals to Communities: Cascading
Effects of Behavioral Impairments
Avoidance of contaminated water, sediment, or food is frequently observed (Table 10.1)
and can have a beneficial effect for wild populations (Figure 10.1). Even if the presence of
a toxicant is detected, avoidance is not automatic as a consequence of interferences with
other environmental factors. Many species are reactive to lighting levels; for instance,
a given species can prefer a habitat highly contaminated but corresponding to its light
preferendum to another clean habitat that does not meet this preferendum (e.g., Scherer
and McNicol 1998). Beneficial at the individual level, avoidance may be responsible for
local extinction of certain species at the ecosystem level. For instance, in North America,
salmonids highly susceptible to metals have probably abandoned habitats in which the
water quality was inadequate. According to Hansen et al. (1999b), the greater sensitivity of
rainbow trout ( Oncorhynchus mykiss ) to metal mixtures may explain, in part, why rainbow
trout populations appear to be more severely affected, compared to brown trout ( Salmo
trutta ) populations in the Clark Fork River (Montana) subjected to historical contamination
by mining and smelting operations.
Feeding impairment is a general stress response exhibited by a variety of organisms in
response to various classes of chemical contaminants (Table 10.1). The amphipod crusta-
cean Gammarus pulex is an important shredding detritivore in many streams. Inhibition of
the in situ feeding rate of G. pulex deployed downstream of a variety of point-source dis-
charges and experimental evidence of a correlation with leaf decomposition rate suggest
that reductions in shredder feeding activity will also translate into reductions in detritus
processing rates in riverine ecosystems (Maltby et al. 2002).
Several behavioral alterations have been observed in mysid crustaceans Neomysis inte-
ger exposed to an inhibitor of AChE activity or to a toxic metal (Figure 10.4). Potential