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Baltic Sea and suffering from pathological impairments, retinyl palmitate levels showed a
negative correlation with POP loads (Nyman et al. 2003). These authors proposed that the
depletion of vitamin A stores may be used as a potential effect biomarker. On the other
hand, PCBs did not affect the retinol status in polar bears (Braathen et al. 2004), and no sig-
nificant relationships were noted between serum, liver, and blubber retinol concentrations,
and serum and blubber OC concentrations in the bowhead whale (
Balaena mysticetus
) (Rosa
et al. 2007). In the first case, the PCB concentrations were nevertheless high enough to affect
five thyroid hormone variables in female polar bears. In the second case, it may be because
bowhead whales have relatively low concentrations of OCs, a threshold effect that has also
been documented in gray heron (
Ardea cinerea
) hatchlings (Jenssen et al. 2001).
Retinoids have been also extensively studied in fish (see review by Rolland 2000),
amphibians (e.g., Boily et al. 2009; Mann et al. 2009), and birds (e.g., Champoux et al. 2006)
including Arctic birds reviewed by Letcher et al. (2010).
4.2.6
δ
-Amino Levulinic Acid Dehydratase
The presence of anthropogenic lead in aquatic systems is largely due to the burning of leaded
fuels, metal smelters, and mining activities. The effect of the removal of lead from gasoline
is clear from numerous studies in urban and remote settings in Europe and North America
(Mahler et al. 2006). However, according to these authors, lead continues to contribute the
largest amount of contamination among the most frequently investigated metals on the basis
of comparison to predicted environmental concentrations, particularly in dense urban water-
sheds. For the marine environment, lead is one of the metals identified by OSPAR as chemi-
cals for priority action. Concentrations in fish, shellfish, and sediments have generally fallen
since 1990 (OSPAR Commission 2009). As much of the reduction in inputs of metals occurred
before 2000, changes in environmental concentrations have been relatively small since 1998 as
concentrations approach, but have not reached, background levels in large parts of the OSPAR
area. Thus, it remains useful to monitor the presence and effects of lead in aquatic biota.
Lead causes a dose-dependent inhibition of δ-amino levulinic acid dehydratase (ALAD),
which is an essential enzyme for the synthesis of hemoglobin in hemopoietic tissue. ALAD
inhibition is recognized as a good indicator of lead exposure, which is quite specific and has
been used in freshwater and marine fish, birds, and mammals. It is thus recommended in the
JAMP Guidelines for Contaminant-Specific Biological Effects (OSPAR Agreement 2008-09).
Lead's effects on ALAD have been also reported for amphibians (Arrieta et al. 2000) and rep-
tiles (Overmann and Krajicek 1995). Although hemoglobin is not synthesized in most bivalves,
ALAD activity is generally negatively correlated with Pb concentration in both freshwater
(Company et al. 2008) and marine bivalve species (Kalman et al. 2008; Company et al. 2011).
4.3 Histocytological Biomarkers
Interest in histocytological biomarkers has been evident for at least two decades as shown
by the early reviews published for invertebrates and fish (Hinton 1993a, 1993b; Yevich and
Yevich 1994). The most commonly used of these biomarkers are externally visible fish dis-
ease, internal fish disease, histopathology of gills and digestive glands in mollusks, and
cytopathology (Table 4.3). They have been widely used in order to reveal biological impacts
of a variety of contaminants/stresses in field studies.
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