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Second, the possible influence of contaminants with CYP1A-
inhibiting potency, such as heavy metals (56, 57), certain di-
ortho PCBs congeners (58), and organotins (59, 60), cannot be
disregarded. Possible organotin contamination in parts of the
MPA is suggested by the results of a study by Terlizi et al. (61),
who recorded signs of imposex, a genital disorder widely used as
a sensitive and specific biomarker of TBT exposure (62), in
specimens of marine snail (Hexaplex trunculus) handpicked in
Zone A of the Egadi Islands MPA. However, levels of imposex
recorded in specimens from the Zone A island of Marettimo
were among the lowest observed in organisms from Italians
MPAs.
Third, teleost MFO responses to aquatic pollutants depend
on many factors: fish sex (63–65), age (66, 67), nutritional and
reproductive status (64, 68), diet (69), water temperature (65, 66,
70), and time course (71, 72) and route (73) of exposure to
chemicals. Temporal fluctuations in the above endogenous and
exogenous factors, as well as variations exposure to pollutants,
have different individual effects on fish MFO activities (74) and
may therefore be useful for interpreting partial discrepancies in
differential degrees of protection applied to each area and
CYP1A activities in C. julis specimens from the MPA. From this
perspective, standardized sampling protocol applied in the
present study led to analysis of homogeneous groups of
specimens, minimizing some of the possible factors of variability.
Last, human impact at each site depends not only on
pollution magnitude and distance from contamination sources,
but also on the hydrodynamics in the area. Although there have
been various oceanographic studies on large-scale circulation of
water bodies in the Mediterranean (for a recent compendium on
the Sicilian Channel and the central Mediterranean, see Astraldi
et al. [75] and Be´ ranger et al. [76]), there have been few
intermediate-scale studies (77), and to our knowledge, nothing
on the Egadi.
At the scale of our study, prevailing winds, which on a small
scale determine surface currents and dispersal of contaminants
(78), may be an important factor for interpreting the present
results. In the Mediterranean, especially in the Tyrrhenian Sea
from north to south as far as the westernmost part of the Sicilian
channel and the Egadi, the prevailing winds are northerlies and
westerlies, especially in winter (Aereonautica Militare Italiana
daily weather and sea forecasts for ships in Italian waters [79]). It Marettimo; Station 5B, Favignana; Station 3B, Levanzo;
is therefore reasonable to expect certain hydrodynamic condi-
tions in the various sites. At Marettimo, Stations 2B (south-
westerly aspect) and 1C (easterly aspect) should be the least
affected by hydrodynamics. Of the four stations near this island,
Station 2B would therefore presumably be the one in which
contaminants transported by currents would be found as a result
of its low hydrodynamics. Personal observations and informa-
tion from local people also indicate that Zone 2B has heavier
trawler and pleasure-boat traffic. Because of the type of bottom,
nets are most often cast in the southern part of the island. Heavy
boat traffic presumably causes additional hydrocarbon contam-
ination. These factors suggest that Zone 2B may be more subject
to anthrogenic impact than the other sites around the island
(Zones 1A, 1B, and 1C).
Of the two areas classified in Zone C, the one surrounding
Marettimo has higher hydrodynamics. Personal observations
and information from local sources indicate that southeasterlies
(Scirocco) may often be so strong that ferries cannot reach the
island. This may be why MFO activities at Station 1C
(Marettimo) were significantly lower than those in Station 1N.
The same considerations apply to the other islands, with
some exceptions that result from coastal morphology and
differing human impact. The port and Cala Rossa at Favignana
face north-northeast, but the former is theoretically one of the
most contaminated in the archipelago as a result of sewage
312 Ó Royal Swedish Academy of Sciences 2007
http://www.ambio.kva.se
outfall and the harbor, whereas the latter is sheltered from all
wind and therefore has lower hydrodynamics, regardless of
prevailing winds. This may explain why EROD activity at
Station 3C was similar to that at Station 1N.
To sum up, the results suggest that hepatic microsomal
EROD and BaPMO activities in C. julis are potentially useful
tools for the assessment of water quality in this MPA. Our
inferences are also supported by the weak but significant
correlation observed between EROD and BaPMO activities in
individual specimens (r ¼ 0.624; p , 0.05) (Fig. 4).
Our results suggest that the MPA may be divided into areas
of different environmental quality (Fig. 1): Stations 1A, 2A, and
1C, inferred as least affected by organic contamination arising
within the MPA; Station 1N, which is presumably the most
threatened by pollution (putatively originating in Favignana
Harbor), but which requires further research for confirmation;
and all the other stations, where environmental quality may be
inferred as being intermediate between the above two groups
and as not differing significantly even between stations subject
to different degrees of protection. This result is in line with a few
studies carried out in Italian MPAs that showed little or no
effect of protection on marine environmental quality (61, 80).
Patella caerulea
Enzyme activities in the two invertebrates are reported in Table
1. As regards enzyme activities in P. caerulea, the highest
NADH–ferry red activities were recorded in specimens from
Station 1B (Marettimo Island Zone B). Values were double, and
significantly higher than, those measured in the other sampling
sites. Enzyme induction in specimens from Station 1B may be
due to exposure to MFO-inducer compounds such as PAHs and
PCBs. Comparison of NADH–ferry red activities between
zones of the MPA showed different trends: half the sites showed
activities that were double those of the other half. This ranking
seemed unrelated to the division into Zones A, B, and C.
Similar results were seen for NADH–cyt c red activity, which
was higher in specimens from Station 1B (Marettimo Island
Zone B) and from Station 1N of Favignana than in limpets
from the other sites. Comparison between zones showed that
limpets from all sites in Zone B except Station 1B (Station 2B,
Station 4B, Formica) had similar average activities without
statistically significant differences between them. The most
interesting observation arose from comparison of the two
reductase activities in each of the four islands, which revealed
remarkably parallel trends.
The present results do not enable us to identify pollution
gradients related to the protection gradient expressed as Zones
A, B, and C. The only previous study in which enzyme activities
in P. caerulea were used in a biomonitoring project was
conducted by our research group in a moderately polluted
marine coastal area of Tuscany (Italy), close to the mouth of the
Arno River. The results of that study showed that NADH–ferry
red activity in the limpet did not correlate with the moderate
levels of PCBs detected in whole body of limpets (Bonacci et al.,
unpublished data). On the other hand, recent in vivo exposure
experiments suggest that reductase activities in the limpet are
potential biomarkers for aquatic environmental quality. Cyto-
chrome P450 catalytic phase I enzymes (such as NADH
ferricyanide reductase and NAD[P]H cytochrome c reductase)
and total P450 content were investigated in the Mediterranean
limpet by in vivo exposure to model CYP1A inducer 2,3,7,8-
TCDD at 5 ppm nominal concentration and to dangerous
aquatic pollutant B(a)P at 0.1, 1, 5, and 10 ppm. A significant
increase (p , 0.05) in all P450 activities and total P450 content
was observed in limpet exposed to 5 ppm of 2,3,7,8-TCDD for
Ambio Vol. 36, No. 4, June 2007