Molecular and Histocytological Biomarkers - Ecological Biomarkers: Indicators of Ecotoxicological Effects - page 90

4.3.1 Responses to Organic Contaminants
Monitoring of oil spills may be based on both invertebrates and fish models. Histological
and ultrastructural studies may provide useful information on the effects of pollutants
on fauna, especially in acute exposures, as reported by Giari et al. (2012). Following the
wreck of the Amoco Cadiz in Brittany, France, responsible for the spillage of 223,000 tons
of petroleum, histological abnormalities were shown in oysters for many years (Berthou
et al. 1987). Neoplasia was observed in soft-shell clams Mya arenaria collected from oil-
impacted sites (Yevich and Barszcz 1977 cited by Yevich and Yevich 1994). Biomonitoring
studies assessing the residual biological effects of pollution caused by the wreck of the
Haven in 1991 on marine organisms in the Ligurian Sea (Italy) were carried out in 1997
(Viarengo et al. 2007) and 1999 (Pietrapiana et al. 2002). Fish with different habitats and
feeding habits were collected from two differently impacted areas and a control site:
Lepidorhombus boscii , Mullus barbatus , Merluccius merluccius , Boops boops , and Uranoscupus
scaber . In addition to this, mussels ( Mytilus galloprovincialis ) were caged along the coast
affected by the Haven disaster. Significant biological responses were observed in lyso-
somal membrane stability, neutral lipid and lipofuscin accumulation, and micronucleus
frequency in mussels caged at two sites close to the Haven wreck (Viarengo et al. 2007).
By using hepatic tissue damage such as the presence of necrotic and tumor-like aspects
(Pietrapiana et al. 2002) as biomarkers of oxidative stress and genotoxicity (Viarengo et al.
2007), it was shown that benthic fish displayed a stress syndrome, whereas few biological
effects were noted in species that had no direct contact with the bottom. However, the
fact that M. barbatus (swimming near the sediment-water interface and eating benthic
prey) remained unaffected suggested interspecific differential sensitivity (Pietrapiana et
al. 2002). The determination of PAH content of mussel and fish tissues and/or the assess-
ment of EROD activity were very useful in order to be able to point out the sources of
biological effects, either the residual effects of the oil spill or chronic habitat pollution
(Viarengo et al. 2007).
An important study of the chemical exposure of fish ( Pleuronectes vetulus, Platichthys
stellatus, Genyonemus lineatus , and Pleuronectes americanus ) was carried out on Pacific
and Atlantic North American coasts using liver toxicopathological lesions (Myers et al.
1998). Risk factors were noticeably enhanced for numerous pollutants (particularly PAHs,
DDT, chlordanes). The hepatotoxicity threshold for PAHs was determined at 940 (680-
1200) μg kg -1 and, in the most polluted sites, prevalence reached 40% of the individuals.
Histopathological examination of fish is relevant to document the presence or absence of
toxicopathological liver lesions involved in hepatocarcinogenesis in English sole ( Parophrys
vetulus ), and these have been causally related to exposure to PAHs (Myers et al. 2008 and
literature quoted therein). Lesions that occur early in the histogenesis of liver neoplasia
can occur in young of the year (<1 year of age) from PAH-contaminated sites, whereas
preneoplastic and neoplastic hepatic lesions are rarely detected in English sole less than 3
years of age. Such lesions are therefore considered effective long-term biomarkers of PAH
exposure.
Yuen et al. (2007) examined morphofunctional changes in the intestine of juvenile
carnivorous fish ( Epinephelus coioides ) upon dietary exposure to environmentally realis-
tic concentrations of the model PAH B[ a ]P for 4 weeks. Significant hyperplasia of basal
enterocytes of mucosal folds was detected shortly after 3 days' exposure to 12.5 μg B[ a ]
P g -1 body weight. These impairments were reversible in the fish upon the abatement of
dietary B[ a ]P. Yuen et al. (2007) concluded that “realistic levels of food borne B[ a ]P could
induce sublethal toxicity in E. coioides. ” Recently, Xing et al. (2012) have reported that,