Behavioral Ecotoxicology - Ecological Biomarkers: Indicators of Ecotoxicological Effects - page 255

of, dissemination of, and reaction to chemosignals are often hormone dependent, espe-
cially for those that have links with reproductive functions (for more details, see review
by Adkins-Regan and Weber in Dell'Omo 2002). In male parr of brown trout Salmo trutta ,
the pyrethroid pesticide cypermethrin had effects on endocrine responses to female odors
and reproductive behavior (Jaensson et al. 2007).
Different pollutants can influence behavior through effects at the interface between an
organism and the ambient medium. In fish and invertebrates, chemoreceptors—but also
light receptors and mechanoreceptors—may be affected by chemicals. Toxicants can act
directly at the surface or indirectly by diffusion through teguments, thus reducing or
modifying the information that reaches the brain (Scarfe et al. 1982; Blaxter and Hallers-
Tjabbes 1992; Scott and Sloman 2004). Subsequent changes in the response of effectors
have potential to influence behavioral performance. Thus, in the Norway lobster Nephrops
norvegicus , several mechanisms may be involved in the effect of manganese exposure on
foraging behavior (Krång and Rosenqvist 2006). This metal may compete with natural
odorants for binding sites on chemosensory receptors, thereby masking chemical sig-
nals from food, as has been shown with mercury in coho salmon Oncorhynchus kisutch . In
hypoxic areas, precipitation of manganese dioxide onto the surface of the antennules could
decrease the permeability of cuticle and thereby disturb odor stimuli diffusion and per-
ception. Manganese could also affect chemoreception by blocking neural signals involved
in odor transduction, as shown in another crustacean, Panulirus argus . In N. norvegicus , the
effect of manganese on antennular chemosensory neurons is unknown, but a blocking
effect on calcium-activated steps in the neuromuscular system has been reported (Krång
and Rosenqvist 2006 and literature cited therein).
Impact of metals on the neuromasts of the lateral line induces an inability in fish to
perform appropriate responses to water currents. However, the cadmium dose needed
to induce such damage in the sea bass Dicentrarchus labrax was 10 times higher than the
concentration occurring in highly polluted estuaries (Faucher et al. 2006). In zebrafish
embryos, the lowest copper dose (68 μg L -1 ) responsible for both histological and behav-
ioral impairment (Johnson et al. 2007) is in the same order of magnitude of environmen-
tal concentrations corresponding to low densities of fish populations in Michigan lakes
(34.0 μg L -1 ) (Ellenberg et al. 1994). For comparison again, in Norway, freshwater fish are
present only when the dissolved copper concentration is less than 60.0 μg L -1 and some
humic acids are present (Eisler 2007).
Many studies have demonstrated the ability of copper to result in olfactory impairments
in fish, particularly salmonids (Hansen et al. 1999a; Sandahl et al. 2007; McIntyre et al.
2008; Green et al. 2010; Baldwin et al. 2011). Carreau and Pyle (2005) showed that exposure
to copper at the embryonic stage of fish Pimephales promelas affects their ability to answer
chemical alarm stimuli later in their life. Because many populations of Pacific salmon
( Oncorhynchus spp.) are listed as threatened or endangered species under the Endangered
Species Act, protectiveness of water quality criteria for copper in United States waters is
focusing on avoidance and olfactory responses to copper by fish (Meyer and Adams 2010;
Deforest et al. 2011).
Many studies have been devoted to the effects of metals, but impairments may also be
induced by a surfactant (linear alkylbenzene sulfonate) in fish (Olsén and Höglund 1985),
by pesticides in zooplankton (Hanazato 2001) and fish (Moore and Waring 1996, 1998, cited
by Scott and Sloman 2004; Moore et al. 2007), polychlorobiphenyls (PCBs) in fish larvae
(McCarthy et al. 2003), and silver nanoparticles in fish (Bilberg et al. 2011). In fish larvae
contaminated by the organochlorine pesticide DDT through parental transfer via the egg
yolk, chemical and visual signals and locomotion were impaired (Faulk et al. 1999).