An experiment using cages was designed to demonstrate herbivore consumption
of Posidonia oceanica (L.) Delile reproductive structures, in a north-west
ern area of the Mediterranean Sea. The percentages of mature inflorescences
and those damaged by herbivores in caged vs, uncaged (control) vs. partial
ly caged plants (artefact control) were compared. Inflorescences damaged by
herbivores were 84.3 +/- 3.1% in the control and 79.5 +/- 3.2 % in partial
cages. Significantly more mature inflorescences were found in caged (37.5
+/- 2.4%) vs. uncaged (10.1 +/- 2.9 %) and partially caged plants (6.7 +/-
0.9 %). The real contribute of herbivores to the loss of fertilised inflore
scences of P. oceanica was approximately 27 %, as the differences between m
ortality in caged and in uncaged plants. These results suggest that herbivo
res could affect sexual reproduction in P. oceanica, but further investigat
ion is needed to investigate biotic interactions in the meadows.