Page 19 - EER-2-2

Explora: Environment
and Resource Trace elements in Mediterranean mussels

species in the tissues of living organisms – to biomagnify by industrial human activities, as evidenced in Table 2,
along the trophic webs. 38-40 which summarizes the maximum values recorded in
Nevertheless, it has been noted that in cases of acute different Mediterranean areas, according to the original
and chronic contamination resulting from natural or investigations. 29,43-47 It is evident that in heavily polluted
anthropogenic causes, elevated mercury levels can be industrial areas, mercury levels in mussels can reach
detected even in the lowest trophic levels, such as bivalve concentrations up to two orders of magnitude higher
mollusks. 41-43 Bruno et al. proposed a large dataset of than the normal ranges observed in reference populations
44
mercury concentrations in the tissues of M. galloprovincialis (Table 1).
to investigate the sources, distribution, and bioaccumulation For instance, Kaštela Bay (Split, Croatia), located on the
of this element in the Mediterranean, observing several central Adriatic coast, has experienced significant mercury
factors that contribute to mercury accumulation in mussels. pollution due to the historical operation of a chlor-alkali
As expected, natural sources, such as volcanic activity and plant. 45,48 This industrial activity led to the accumulation
geological anomalies, play a significant role, particularly of high levels of mercury in the sediment, which can be
in the Tyrrhenian Sea. However, anthropogenic activities, remobilized and become bioavailable to marine organisms.
including mining, industrial processes, and urban runoff, Biomonitoring studies have been conducted in this area
are also major contributors. They also observed that using M. galloprovincialis as a sentinel species. Mussels
mercury bioaccumulation in mussels is influenced by water were transplanted from clean areas to different stations
temperature, salinity, and the availability of organic matter. within the bay to monitor their uptake of mercury and
Significant spatial and temporal variations in mercury levels its methylated form, methylmercury. Mussels efficiently
in mussels have also been observed: higher concentrations accumulate both total mercury and methylmercury
were reported from coastal areas with intense human from the contaminated environment, and inorganic
activities, such as industrial zones and ports. However, even mercury was observed to be the predominant form. As it
in relatively pristine areas, elevated mercury levels were is relatively well known that inorganic mercury in nature
found, confirming the influence of natural sources and can be rapidly converted to methylmercury by numerous
long-range atmospheric transport. Climate change can alter anaerobic organisms, 39,49 the bioaccumulation of high
the distribution and fate of mercury in the environment, levels of inorganic mercury suggests the presence of active
potentially leading to increased exposure. 44 and ongoing contamination. A strong positive correlation
Nevertheless, the highest mercury concentrations in was observed between mercury concentrations in mussel
mussels have been observed in regions severely affected tissues and sediment, suggesting that sediment-bound

Table 2. Maximum mercury levels in whole mussel tissues from Mediterranean sites affected by severe anthropogenic pressure or
natural enrichment due to geological anomalies, according to original investigations 29,43-47
Site Area Main source of contamination Hg (µg/g)
Kaštela bay (Split, Croatia) Central Adriatic Sea Industrial pollution 27.34
Leghorn harbour (Italy) Ligurian Sea Industrial pollution 19.99
Gulf of Naples (Italy) Tyrrhenian Sea Volcanic activity 10.02
Mouth of the Gromolo torrent (Genoa, Italy) Ligurian Sea Mount Amiata cinnabar anomaly 6.69
Gulf of Trieste (Trieste, Italy) Northern Adriatic Sea Industrial pollution 6.62
Tremiti Islands (Italy) Southern Adriatic Sea Maritime traffic and urban pollution 5.31
Augusta Bay (Eastern Sicily, Italy) Tyrrhenian Sea Industrial pollution 5.00
Marano Lagoon (Udine, Italy) Northern Adriatic Sea Industrial pollution 4.85
Portoscuso (South Sardinia, Italy) Tyrrhenian Sea Industrial pollution 3.58
Bosphorus Canal (Turkey) Marmara Sea Maritime traffic and urban pollution 2.94
Oran coast (Western Algeria) West Mediterranean Mining activities 2.27
S.Benedetto-Pescara coast (Italy) Central Adriatic Sea Maritime traffic and urban pollution 1.93
Po Delta (Italy) Northern Adriatic Sea Industrial and urban pollution 1.70
Ancona harbour (Italy) Central Adriatic Sea Maritime traffic and urban pollution 1.20
Note: Data are expressed in µg/g (dry weight).
Abbreviation: Hg: Mercury.

Volume 2 Issue 2 (2025) 9 doi: 10.36922/eer.8078