Proceedings of the Second Mediterranean Symposium on Marine

Table 1: Mercury concentration (in ng.g -1 <strong>of</strong> dry weight) in <strong>the</strong> scales, <strong>the</strong> rhizomes (Rhiz.) and <strong>the</strong>
belowground part (Below. p.) <strong>of</strong> Posidonia oceanica – Lepid. year: lepidochronological year; Maci.:
Macinaggio. Confidence intervals are indicated on 95% threshold.
Lepid. year 1997 1998 1999 2000 2001 Mean
Scales
Rhiz.
Below. p.
Bastia 82.6±15.0 68.9±7.5 68.1±9.7 76.4±11.6 54.5±8.1 69.7±5.2
Lumio 58.0±12.3 51.8±5.7 59.7±16.6 42.9±4.9 44.3±5.2 51.2±4.7
Maci. 51.0±6.4 56.8±8.3 60.4±6.9 56.4±6.1 48.3±10.7 54.6±3.6
Mean 62.7±8.0 58.8±4.8 62.6±6.8 58.6±6.7 49.0±4.9 58.2±2.9
Bastia 57.1±10.3 54.5±5.2 75.6±13.3 79.4±12.4 98.5±12.9 72.1±6.7
Lumio 58.5±16.2 45.0±7.5 71.8±12.1 66.4±9.5 81.6±6.5 63.9±5.9
Maci. 58.7±13.6 48.4±5.8 74.3±11.4 77.3±10.9 89.1±10.7 68.6±6.2
Mean 58.1±7.6 49.3±3.8 73.8±6.8 73.9±6.4 90.1±6.6 68.1±3.6
Bastia 71.8±13.0 63.1±6.6 70.8±11.0 77.3±11.8 61.8±8.9 69.0±5.7
Lumio 58.2±14.0 49.2±6.4 64.9±14.6 51.0±6.5 50.3±5.4 54.7±5.9
Maci. 54.6±9.8 53.2±7.2 66.0±8.7 63.7±7.8 55.7±10.7 58.6±5.1
Mean 61.5±10.2 55.2±8.1 67.2±3.6 64.0±14.9 55.9±6.5 60.8±4.3
Finally, for each site, <strong>the</strong> mercury concentrations, all years mingled, are higher in <strong>the</strong>
rhizomes than in <strong>the</strong> scales, but this difference is significant only for <strong>the</strong> sites <strong>of</strong> Lumio
and Macinaggio (ANOVA, p = 0.0002 and p = 0.0001 respectively, Fig 2). Regarding
only <strong>the</strong> concentrations in <strong>the</strong> scales, all years mingled, <strong>the</strong> concentrations are
significantly higher in Bastia (ANOVA, p = 0.00001) than in <strong>the</strong> two o<strong>the</strong>rs sites (Fig. 2).
For <strong>the</strong> rhizomes, <strong>the</strong> tendency is <strong>the</strong> same but <strong>the</strong> differences between sites are not
significant (ANOVA, p = 0.0636; Fig. 2).
Fig. 2: Mercury concentration (in ng.g-1 dry weight) in scales and rhizomes <strong>of</strong> Posidonia oceanica in
function <strong>of</strong> <strong>the</strong> site, all years mingled.
• Influence <strong>of</strong> <strong>the</strong> site
The average mercury concentration in <strong>the</strong> belowground part is determined taking into
account <strong>the</strong> relative contribution <strong>of</strong> each tissue. The previously observed tendencies stay
valid. All years mingled, Bastia presents <strong>the</strong> highest concentrations compared to Lumio
and Macinaggio, which are little different one <strong>of</strong> <strong>the</strong> o<strong>the</strong>r (Table 1).
• Influence <strong>of</strong> <strong>the</strong> year
Annual differences <strong>of</strong> <strong>the</strong> mercury concentrations are recorded all sites and tissues
mingled (Table 1). The 1998 year presents <strong>the</strong> weakest concentrations, whereas <strong>the</strong>
maximal concentrations are observed for <strong>the</strong> year 1999.
ACTES DU DEUXIEME SYMPOSIUM MEDITERRANEEN SUR LA VEGETATION MARINE (ATHENES, 12-13 DECEMBRE 2003)
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