A number of important ecological questions were covered by this
preliminary study: (i) Are there large variations in environmental
conditions that could explain the differences in microbial communities
at regional scale? (ii)What microbial groups (bacteria, archae,
picoeukaryotes) are characteristic of these “pristine” ecosystems
and distinguish them from ecosystems subject to anthropogenic
effects (iii)? What is the main factor controlling bacterial dynamics
(nutrient limitation versus HNF predation)?
To answer these questions, the abundances of microbial communities
(virus, bacteria, protists and phytoplankton) and metazooplankton
in the lagoon and ocean sites around each island were
determined and the relationships between environmental conditions
and biological components at regional scale were studied.
PCR-DGGE analysiswas used to characterize the genetic diversity of
the main groups of picoplankton. To gain insight into the potential
consequences of nutrient enrichment in these ecosystems, the effects
of nutrient enrichment on bacterial dynamics were determined
experimentally