## 3 Results
### Total Hg in Biota
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**EUFG** & **Species** & **Year** & **Ltot (cm)** & \begin{tabular}{c} **THg** \\ **(mg kg\({}^{-1}\))** \\ \end{tabular} & **Ltot (cm)** & \begin{tabular}{c} **THg** \\ **(mg kg\({}^{-1}\))** \\ \end{tabular} & **Ltot (cm)** & \
\begin{tabular}{c} **THg** \\ **(cm)** \\ \end{tabular} & **Ltot** &
\begin{tabular}{c} **THg** \\ **(mg kg\({}^{-1}\))** \\ \end{tabular} \\ \hline Estuarine & _Atherina boyeri_ & 2012 & 7.8–8.6 & 0.17–0.28 & **7.6–8.1** & **0.23–0.78** & _8.4_ & _0.72_ \\  & _Salaria pavo_ & 2010/2011 & 8.2 & 1.74 & **8.3** & **1.6** & _nd_ & _nd_ \\  & _Zaestersson phicyclnulus_ & 2010/2011 & 7.4–12.6 & 0.16–0.49 & **nd** & **nd** & _10.2_ & _0.61_ \\  & _Aphanus fasciatus_ & 2010/2011 & 4.1 & 0.21 & **nd** & **nd** & _4.4–4.8_ & _0.4–0.74_ \\  & _Pomatoschistus canestrini_ & 2010/2011 & 4.4 & 0.04 & **nd** & _nd_ & _nd_ & _nd_ \\  & _Alosa fillax_ & 2010/2011 & 28.5 & 0.76 & **nd** & _nd_ & _nd_ & _nd_ \\  & _Engranulis encrasicchio_ & 2010/2011 & 9 & 0.07–0.17 & **nd** & **nd** & _nd_ & _nd_ \\  & _Chlon auratus_ & 2021 & 24.6–30.9 & 0.1–0.18 & **24.3–29.5** & **0.23–0.5** & _21_ & _0.39_ \\ \hline \hline \end{tabular} Note: **in bold** are the results on individuals collected in the Grado Lagoon, and _in italics_, are those collected at Val Cavanata (FM1). n.d.: not determined.  
\end{table} 
Table 5: Total Hg concentrations in selected fishes collected in the Marano and Grado Lagoons. ranges between 5-20, and the sedimentary habitat is without vegetation [113; 114]. Moreover, it is included in Annex II of the Habitat Directive [115]. This species was recorded only in the most confined areas of the Marano basin close to the river mouths [112], and the THg data obtained in this work represents a novelty for adult male specimens of this species. The Mediterranean banded killifish (_Aphanius fasciatus_) is a typical euryhaline fish species that inhabit the brackish environment, lagoons, estuaries, and salina. It is rarely found in freshwater habitats [116]. It is also included in Annex II of the Habitat Directive, and, due to its euryhaline characteristics, it was constantly recorded in every WB type of the MGL, being particularly abundant at FM1 [112]. THg concentrations were significantly higher in FM1 specimens than in Marano specimens. Unfortunately, specimens from Grado were not collected, but it should be noted that, based on data published by [PERSON] [69], individuals of 4-4.5 cm TL caught in a fish farm in the eastern area of the Grado Lagoon showed THg values ranging from 0.49 to 1.7 mg kg\({}^{-1}\). The peacock blenny (_S. pavo_) is typical in the intertidal zone and very shallow water (from 0 to 2 m), and it is a euryhaline species commonly found in brackish waters such as lagoons [117]. Only two adult specimens were analysed and both of them revealed the highest THg values recorded (1.6 and 1.7 mg kg\({}^{-1}\) ww). The grass goby (_Z. ophioccephalus_) is a brackish goby widely distributed in the estuarine and lagoon environments of the Mediterranean basin [118; 119] and is particularly abundant in the northern Adriatic Sea, Black Sea, and the Sea of Azov [120]. In the largest northern Adriatic lagoons (Venice and Marano--Grado Lagoon), where its exploitation has occurred since the twelfth century, it is one of the most important target species of artisanal fisheries [119]. The sexual maturity of _Z. ophioccephalus_ occurs in the first year of life when individuals reach a size of approximately 7.5 cm in TL [119]. The TL of the specimens examined in this study ranged from 7.4 to 12.6 cm, and, as with other species, the highest values of THg peaked at FM1 (0.61 mg kg\({}^{-1}\) ww), whereas the minimum value (0.16 mg kg\({}^{-1}\) ww) was recorded in the smaller individual (7.4 cm TL) caught in the Marano basin. Nevertheless, the general assumption of the occurrence of a significant positive relationship between TL and THg, at least for this species, cannot be assumed.