## 3 Results and Discussion
### Total Fatty Acid (TFA) Analysis  
In addition to the determination of total fat (%), a more detailed analysis and identification of the contained fatty acids were carried out for all the samples using gas chromatography. The results are presented in Figures 4 and 5. As can be seen in Figures 5 and 6, which depict the total fatty acids detected in the samples, for the Evoikos Gulf, it is observed that palmitic acid (C16:0) was detected in the largest amount compared to the other fatty acids throughout the year. It is also observed that the highest fatty acid concentrations were found in autumn (C16:0 = 16.53%, C18:0 = 13.34%, C22:2 = 11.63%, etc.). For the Saronic Gulf, fatty acids C18 (18.03%) and C22:6n3 (16.58%) were detected in the highest concentrations. In addition, it was also observed here that the highest concentration was measured in autumn. Figure 4: Mean values of moisture content of oyster samples in relation to season and location. The sampling was performed from autumn 2019 to summer 2020. Superscripts letters denote statistically significant different values (\(p<0.05\)) between different seasons for each location. Figure 5: Summary chart of the fatty acid composition of samples from the Evoikos Gulf. The sampling was performed from autumn 2019 to summer 2020. Figure 7 shows the seasonal distribution of grouped fatty acids based on the existence of double bonds in their molecules. From this diagram, it is observed that overall, the polyunsaturated facts were the ones that were detected in the highest amounts for each month and for each location, apart from spring in the Evoikos Gulf, where the monounsaturated fats had a higher value. The values of the grouped fatty acids are also presented in Table 2, where it is verified from their statistical analysis that no statistically significant differences were detected for each category of acids between the locations and seasons. Moreover, in Table 2, the ratios of polyunsaturated to saturated fatty acids are presented, as these parameters are very important indicators of the nutritional quality of seafood [29]. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Location** & **Season** & \(\Sigma\)**SFAs** & \(\Sigma\)**MUFAs** & \(\Sigma\)**PUFAs** & \(\Sigma\)**PUFAs/ESFAs** \\ \hline \multirow{4}{*}{Evoikos Gulf} & Autumn & 31.55 \({}^{\pm}\) 5.096 & 30.33 \({}^{\pm}\) 6.125 & 44.34 \({}^{\pm}\) 14.56 & 1.380 \({}^{\pm}\) 0.235 \\  & Winter & 27.33 \({}^{\mathrm{a,b}}\) \(\pm\) 2.028 & 21.25 \({}^{\pm}\) 9.639 & 29.56 \({}^{\mathrm{b}}\) \(\pm\) 6.128 & 1.083 \({}^{\pm}\) 0.226 \\ \cline{1-1}  & Spring & 19.04 \({}^{\mathrm{b}}\) \(\pm\) 2.937 & 30.60 \({}^{\pm}\) 3.506 & 26.11 \({}^{\mathrm{b}}\) \(\pm\) 14.03 & 1.321 \({}^{\pm}\) 0.561 \\ \cline{1-1}  & Summer & 24.86 \({}^{\mathrm{a,b}}\) \(\pm\) 2.868 & 25.26 \({}^{\mathrm{a}}\) \(\pm\) 2.673 & 32.80 \({}^{\mathrm{a,b}}\) \(\pm\) 6.416 & 1.328 \({}^{\mathrm{a}}\) \(\pm\) 0.304 \\ \hline \end{tabular}
\end{table} 
Table 2: Content (%) of the samples in saturated (\(\Sigma\)SFAs), monounsaturated (\(\Sigma\)MUFAs), and polyunsaturated (\(\Sigma\)PUFAs) fatty acids and ratio of polyunsaturated/saturated (\(\Sigma\)PUFAs/\(\Sigma\)SFAs) fatty acids for the two studied locations for a whole year. Figure 6: Summary chart of the fatty acid composition of samples in the Saronic Gulf. The sampling was performed from autumn 2019 to summer 2020. Figure 7: Summary chart of the fatty acid composition of samples in both studied locations. The sampling was performed from autumn 2019 to summer 2020. From the polyunsaturated fatty acids, docasapentanoic acid (DPA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are very important ingredients for nutrition with proven beneficial properties in the treatment of heart diseases, cancer, etc. [2]. For this reason and as shown in Figure 8, they were also studied separately from the rest of the fatty acids.