Ecotoxicology and Genotoxicology by Larramendy Marcelo L; Rico-Martinez Roberto; Waters Michael D

Author:Larramendy, Marcelo L; Rico-Martinez, Roberto; Waters, Michael D
Language: eng
Format: epub
Publisher: Royal Society of Chemistry
Published: 2017-06-21T04:00:00+00:00

Figure 11.12 Map demonstrating example study areas receiving pollutants from different sources and the potential fish sampling points for assessment of aquatic genotoxicity in river (A: upstream; B: downstream), sea (C: contaminated; D: reference) and lake (E: contaminated; F: reference) waters (drawing by T. Cavas).

In sea and lake environments, the sampling stations are selected on the basis of pollution levels, such as at or near discharge points of domestic and industrial effluents or close to agricultural areas (Figure 11.12C, E), whereas control stations must be considerably far from these points and lack such discharges or activities (Figure 11.12D, F). In a study performed by Cavas and Ergene-Gozukara, analysis of micronucleus frequencies in erythrocytes of M. cephalus sampled from Mediterranean coast of Turkey revealed higher genotoxic damage in fish captured from Mersin and Karaduvar harbors receiving discharges from chromium, manure and soda factories in comparison to those captured from Erdemli area about 45 km west of the Mersin and Karaduvar harbors, which receives no industrial point source discharges and is a relatively unpolluted area.47 Recently, Hyllanda et al. performed a large scale analysis in marine environments using dab (Limanda limanda) as a sentinel species and the Comet assay as a genotoxicity endpoint.85 Fish samples were collected at five stations in the North Sea that were influenced by inputs from industrial and maritime activities as well as oil and gas platforms. On the other hand, two other stations in Iceland were selected as reference areas and fish collected from these areas served as controls. The authors reported that the genotoxic response was higher in fish collected from polluted locations in comparison to those collected in reference areas. Furthermore, Simonyan et al. performed an in situ genotoxicity analysis in the basin of Lake Sevan (Armenia) using the Comet assay on erythrocytes of Carassius auratus gibelio.86 Fish were sampled from three polluted and a relatively unpolluted location approximately 10 km from the affected area. The obtained data revealed higher DNA damage in fish collected from areas polluted with agricultural and urban wastes.

An inherent weakness of an in situ study using wild fish is the lack of a true negative control. In fact, finding a suitable negative control might not always be possible when assessing the effects of genotoxic pollution on native fish populations under field conditions. This is mainly due to factors such as seasonality, migration, unavailability of certain species or lack of sufficient/homogeneous specimens.14,47,50,61 To overcome this problem, two approaches can be used. First, in situ exposure of caged fish. Second, transfer and recovery of field-collected native fish in clean water under laboratory conditions.

The use of the in situ caging approach has advantages as it provides the opportunity to conduct more controlled experiments under field conditions.14,87–89 Fish from the same species/sex/age groups can be used as well as exposures can be performed at the desired location and duration. Furthermore, the cages can be placed at the desired depth according to the study design (i.e. surface water or sediment exposure) or to the biology of the selected species (Figure 11.

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