farm. According to correlation matrices, TOM was positively correlated with
all heavy metals except iron and lead (P ˂ 0.05). Liang et al. (2012) reported
that organic matter is the most important agent influencing the distribution of
heavy metals in the various mariculture sediments. All intertrace metal correlations were positive except for Cd and Pb, where there was correlation, but it
was statistically insignificant (P > 0.05), suggesting that these metals are not
associated with each other and that their transport behavior is not identical in
the marine environment. In addition, a positive correlation was observed
between Fe vs. Cu, Zn, Cd, Pb, and TOM, but no significance (P > 0.05) was
found between Fe and TOM or other heavy metals, suggesting that these
metals are not associated with each other; these correlations indicate that
these heavy metals could have different anthropogenic and natural sources
in the sediments of the study area.
Heavy metal assessment and ecological risk in sediment
The enrichment factor (EF), geo-accumulation index (Igeo), adverse effects
index (AEI), and the mean effects range medium quotient (MERM-Q)
were used to evaluate the ecotoxicological status of fish farm sediment
(Table 4).
The geo-accumulation index (Igeo) provides a direct measure of the degree
of enrichment by heavy metals in the sediment (Alves, Ferreira, and Soares
2018). The geo-accumulation index (Igeo) values calculated in this study
showed that all heavy metals were in the uncontaminated class (Igeo < 0).
These results were in harmony with Ustaoğlu and Tepe’s (2019) results.
The EF values were observed to be higher than 1 for all metals around the
fish cages. Outside this area, the observed EF values of Zn and Pb were above 1.
Enrichment factor (EF) is an appropriate tool to distinguish between anthropogenic and natural events (Gao et al. 2015). This suggests that the main
source of metals comes from anthropogenic activities, considering the proximity of the fish farm to the harbor and tourist complexes; those contaminants
are mainly trapped and deposited in the marine sediments of the investigated
sites. Marine sediments under the fish cages were moderately enriched (EF
> 2) with Zn and Pb. Moderate enrichment is observed in all marine sediment
of the study zone for Pb and Zn, except in reference site for Zn, which is in
agreement with the results of Benson et al. (2017). This leads us to classify the
Azeffoun fish farm as an unpolluted area.
To interpret the content of metals in sediments in the context of their
potential biological effect, AEI and MERM-Q were calculated. In all monitored
zones AEI values were lower than 1 for all metals. The concentration of metals
in the sample is not high enough to cause adverse effects on biota along the
monitoring area. In addition to that, the mean ERM quotient is an approach
that has proven useful in determining the potential biological effect of
8
R. LOUNAS ET AL.
all heavy metals except iron and lead (P ˂ 0.05). Liang et al. (2012) reported
that organic matter is the most important agent influencing the distribution of
heavy metals in the various mariculture sediments. All intertrace metal correlations were positive except for Cd and Pb, where there was correlation, but it
was statistically insignificant (P > 0.05), suggesting that these metals are not
associated with each other and that their transport behavior is not identical in
the marine environment. In addition, a positive correlation was observed
between Fe vs. Cu, Zn, Cd, Pb, and TOM, but no significance (P > 0.05) was
found between Fe and TOM or other heavy metals, suggesting that these
metals are not associated with each other; these correlations indicate that
these heavy metals could have different anthropogenic and natural sources
in the sediments of the study area.
Heavy metal assessment and ecological risk in sediment
The enrichment factor (EF), geo-accumulation index (Igeo), adverse effects
index (AEI), and the mean effects range medium quotient (MERM-Q)
were used to evaluate the ecotoxicological status of fish farm sediment
(Table 4).
The geo-accumulation index (Igeo) provides a direct measure of the degree
of enrichment by heavy metals in the sediment (Alves, Ferreira, and Soares
2018). The geo-accumulation index (Igeo) values calculated in this study
showed that all heavy metals were in the uncontaminated class (Igeo < 0).
These results were in harmony with Ustaoğlu and Tepe’s (2019) results.
The EF values were observed to be higher than 1 for all metals around the
fish cages. Outside this area, the observed EF values of Zn and Pb were above 1.
Enrichment factor (EF) is an appropriate tool to distinguish between anthropogenic and natural events (Gao et al. 2015). This suggests that the main
source of metals comes from anthropogenic activities, considering the proximity of the fish farm to the harbor and tourist complexes; those contaminants
are mainly trapped and deposited in the marine sediments of the investigated
sites. Marine sediments under the fish cages were moderately enriched (EF
> 2) with Zn and Pb. Moderate enrichment is observed in all marine sediment
of the study zone for Pb and Zn, except in reference site for Zn, which is in
agreement with the results of Benson et al. (2017). This leads us to classify the
Azeffoun fish farm as an unpolluted area.
To interpret the content of metals in sediments in the context of their
potential biological effect, AEI and MERM-Q were calculated. In all monitored
zones AEI values were lower than 1 for all metals. The concentration of metals
in the sample is not high enough to cause adverse effects on biota along the
monitoring area. In addition to that, the mean ERM quotient is an approach
that has proven useful in determining the potential biological effect of
8
R. LOUNAS ET AL.