A multi-biomarker approach for
freshwater wetland pollution monitoring - an application to Pateira de
Fermentelos (Portugal)
Maria Ana Santos, Mário Pacheco, Iqbal Ahmad Vera Lúcia Maria & Mariana Teles
CESAM
(Centre for Environmental and
Marine Studies) &
Department of Biology
University
of Aveiro, Portugal
Artificial lakes such as dams where still waters are
found, due to their specific configuration and water dynamics, are more prone
to receive and accumulate anthropogenic discharges resulting from domestic,
municipal and industrial effluents as well as agriculture runoff. Hence,
organisms’ synergistic/antagonistic responses to
a mixture of contaminants are hardly interpreted and predicted exclusively by
chemical analysis of those contaminants. In this context, the use of biomarkers
has been demonstrated to be a suitable alternative for monitoring and
management of these aquatic ecosystems. Pateira de Fermentelos (Portugal) is an
important fishing and recreation place, receiving effluents from different
origins namely, electroplating industrial effluents containing heavy metals,
domestic wastes, as well as pesticides and fertilizers from agriculture
activities. In this perspective, our research group carried out an in situ study along this impacted freshwater
wetland where adult eels (Anguilla anguilla L.) were caged and
plunged for 48 h at different sites (Figure 1 - A, B, C, D) differing in their
distances to the main known pollution source (Cértima River). Thus, three sets
of biomarkers concerning (i) genotoxicity, (ii) oxidative stress responses and
(iii) endocrine alterations were adopted.
Figure 1.
The presence of pro and/or genotoxic compounds was
detected as expressed in the DNA integrity loss induced in different target
tissues (gill, blood and liver), displaying a decreasing genotoxic gradient
from the initial to the ending part of the water body.
The activation of antioxidant enzymes (as observed in
gill) as well as their inhibition (as observed in kidney and liver) provided a
clear indication of pollution presence and environmental health degradation.
All the organs revealed a similar resistance to peroxidative damage (LPO),
suggesting that the antioxidants are more responsive biomarkers than LPO for
short-term exposures.
Endocrine and metabolic biomarkers revealed increased
plasma cortisol and glucose concentrations at all exposure sites, signalling
the presence of stressors. Thyroid metabolism disruption was detected at the
closest site to the main pollution source. In addition, the eel’s plasma
17β-estradiol increase was observed indicating water contamination by this
particular steroid.
Despite the complexity of fish overall responses to
mixtures of contaminants, the assessed biomarkers were able to express
site-specific responses, demonstrating their ability to detect the presence of
a wide range of chemicals. A. anguilla in
situ trial proved its high ability for freshwater monitoring, contributing to
a better knowledge of fish toxicological responses to mixtures of contaminants.
Moreover, the monitoring efficacy can be greatly improved by using batteries of
non-specific biomarkers comprising different biological levels.
Selected publications:
[1]
Maria, V.L., Pacheco, M. and Santos, M.A. 2006. Anguilla anguilla L. genotoxic responses after in situ exposure to freshwater wetland (Pateira de Fermentelos,
Portugal). Environment International 32(4): 510-515.
[2] Ahmad, I., Pacheco, M. and Santos, M.A. 2006. Anguilla anguilla L. oxidative stress
biomarkers: an in situ study of
freshwater wetland ecosystem (Pateira de Fermentelos, Portugal). Chemosphere
65(6): 952-962.
[3] Teles, M., Pacheco, M. and Santos, M.A. 2007.
Endocrine and metabolic responses of Anguilla
anguilla L. caged in a freshwater-wetland (Pateira de Fermentelos - Portugal).
The Science of the Total Environment 372(2-3): 562-570.
Research Team:
Maria Ana Santos, Full Professor at the University of Aveiro, Department of Biology
Mário Pacheco, Assistant Professor at the University of Aveiro, Department of Biology
Iqbal Ahmad, Post-doctorate Fellow
Vera Lúcia Maria, Post-doctorate Fellow
Mariana Teles, Post-doctorate Fellow