| Abstract |
Marine metal pollution may lead to ecosystem degradation, toxic effects on sealife and
potential public health risks. Bioindicators are species used to assess ecosystem pollution
and its consequences. Fish can serve as bioindicators since they accumulate metals.
However, this trait of theirs is also the reason why assessment of risks and benefits from
their consumption becomes essential. Fish bioaccumulation depends on various factors that
ought to be investigated.
In the current study, the presence of several metals and elements (Li, Na, Mg, P, Ca, V,
Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Mo, Pd, Cd, Cs, Ba, Hg, Tl, Pb, U) in the tissues of
sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) is investigated with a view
to 1) assessing whether they can be used as bioindicator species of marine metal pollution,
2) conducting public health risk and benefits assessment and finally, 3) investigating sitespecific,
species-specific, size-specific impact and proximate composition influence on metal
bioaccumulation. Sampling took place in 6 areas along the Greek coastline: Thermaikos Gulf,
Amvrakikos Gulf, Inner Saronikos Gulf (Elefsina), Strymonian Gulf, Thracian Sea and
Artemisium Straits.
Sardine and anchovy provided a thorough view of marine metal load in accordance with
local pollution sources in each site investigated. They accurately depicted site-specific
differences, showed positive correlation to metal concentrations measured in seawater and
met several other assessment criteria. Thus, sardine and anchovy can be evaluated as
appropriate, reliable and particularly useful bioindicator species that can contribute to the
quantification of marine metal pollution, to identifying its sources, to conducting spatial
comparisons and public health risk-benefits assessment.
Health benefits arising from fish metal content seem to outweigh the risks, since various
parameters assessed indicated safe consumption of the studied species. Weekly
consumption of 480,76 g of sardine and anchovy poses minor risks (due to increased levels
of essential elements like Fe and Zn in some cases) but great benefits regarding intake of
essential elements like Mg, Fe, Cu, Zn, Mo, Ca, P, Se. Traces of potentially toxic inorganic As
were detected in Artemisium Straits but were well below all safety limits. Hg toxicity
symptoms are not likely to appear and Se benefits are not likely to be compromised.
Despite the statistically significant differences in metal pollution among the studied sites,
it was the essential elements Na, P, Ca, Mg, Fe and Zn that were found in higher
concentrations in all cases. The wide range of pressures (urban, industrial, port and
agricultural) applied in Inner Saronikos Gulf and Thermaikos Gulf is depicted not only in the
kind of elements found in maximum levels but also in the large number of these elements
reaching maximum concentrations among sites. On the contrary, in the rest of the sites, only
a few or very few elements were found in maximum levels, either due to the fact that
pressures applied were low or arising from agricultural activities, or due to local morphology,
water circulation or dilution. In several cases maximum concentrations resulted from high
background metal levels.
Statistical analysis revealed both species- and site-specific metal bioaccumulation. The
impact of both of these factors on metal accumulation can be seen at the same time without
overshadowing or explaining each other. A clear trend towards larger bioaccumulation in
anchovy compared to sardine was observed for most of the metals studied. The main drivers
of the species-specific differences in metal bioaccumulation seem to be proximate
composition, size, diet and trophic level. Proximate composition (lipids, proteins, ash,
moisture) and size (length, weight) influence on bioaccumulation is not standard but
strongly dependent on the species and the metal studied. General trends towards positive
correlation to most metals were observed for proteins and ash, a general trend towards
negative correlation was observed for size, while negative correlations or absence of
correlation prevail for lipids and moisture, depending on the species.
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Εκτίμηση της ρύπανσης του θαλάσσιου περιβάλλοντος από μέταλλα με τη χρήση γαύρου (Engraulis encrasicolus) και σαρδέλας (Sardina pilchardus) ως βιοδεικτών, εκτίμηση κινδύνων και οφελών στη δημόσια υγεία και διερεύνηση παραγόντων που επηρεάζουν τη βιοσυσσώρευση μετάλλων
