Author(s):
Carrola, João 
; Santos, Nádia ; Rocha, Maria J. ; Fontainhas-Fernandes, António ; Pardal, M. A. ; Monteiro, Rogério A. F. ; Rocha, Eduardo
Date: 2014
Persistent ID: http://hdl.handle.net/10316/25773
Origin: Estudo Geral - Universidade de Coimbra
Subject(s): Fish; Blood; Erythrocytes; Micronuclei; Toxicology; Biomarkers
Description
Fish are bioindicators of water pollution, and an
increased rate of their erythrocyte nuclear morphological abnormalities
(ENMAs)—and particularly of erythrocyte
micronuclei (EMN)—is used as a genotoxicity biomarker.
Despite the potential value of ENMAs andMN, there is scarce
information about fish captured in Iberian estuaries. This is the
case of the Portuguese estuaries of the Mondego, Douro and
Ave, suffering from different levels of environmental stress
and where chemical surveys have been disclosing significant
amounts of certain pollutants. So, the aim of this study was to
evaluate genotoxicants impacts and infer about the exposure
at those ecosystems, using the greymullet (Mugil cephalus) as
bioindicator and considering the type and frequency of nuclear
abnormalities of erythrocytes as proxies of genotoxicity.
Sampling of mullets was done throughout the year in the
important Mondego, Douro and Ave River estuaries (centre
and north-western Portugal). The fish (total n=242) were
caught in campaigns made in spring–summer and autumn–
winter, using nets or fishing rods. The sampled mullets were
comparable between locations in terms of the basic biometric
parameters. Blood smears were stained with Diff-Quik to assess
the frequencies of six types of ENMAs and MN (given per
1,000 erythrocytes). Some basic water physicochemical parameters
were recorded to search for fluctuations matching the
ENMAs. Overall, the most frequent nucleus abnormality was
the polymorphic type, sequentially followed by the blebbed/
lobed/notched, segmented, kidney shaped, vacuolated,MNand
binucleated. The total average frequency of the ENMAs ranged
from 73‰in the Mondego to 108‰in the Ave. The polymorphic
type was typically ≥50 % of the total ENMAs, averaging
about 51‰, when considering all three estuaries. The most
serious lesion—the MN—in fish from Mondego and Douro
had a similar frequency (≈0.38‰), which was significantly
lower than that in the Ave (0.75‰). No significant seasonal
differences existed as to the MN rates and seasonal differences
existed almost only in the Douro, with the higher values in AW.
In general, the pattern of ENMAs frequencies was unrelated
with the water physicochemical parameters. Considering the
data for both the total ENMAs and for each specific abnormality,
and bearing in mind that values of MN in fish erythrocytes
>0.3‰ usually reflect pollution by genotoxicants, it is suggested
that mullets were likely being chronically exposed to
such compounds, even in the allegedly less polluted ecosystem
(Mondego). Moreover, data supported the following pollution exposure gradient: Mondego<Douro<Ave. The scenario and
inferences nicely agree with the published data from chemical
monitoring. This work was partially supported by the European
Regional Development Fund (ERDF) funds through the Competitiveness
and Trade Expansion Program (COMPETE), and by National Funds
provided by Fundação para a Ciência e a Tecnologia (FCT), via the
research projects PTDC/MAR/70436/2006, PEst-C/MAR/LA0015/
2011, PEst-C/MAR/LA0015/2013, and also by the PhD grant
SFRH/BD/25746/2005.
