following
the extensive coral bleaching event in 1998, and only a few studies
have considered the biodiversity, structure and functioning of the
marine microbial communities in these islands (for example, the
nutrient status was studied by Riaux-Gobin et al. (2011)).
Ecological baselines for the structure and functioning of ecosystems
in the absence of human activity can provide essential
information for conservation and restoration. The lack of “reference
environments” raises serious problems: (1) limited knowledge
about the diversity and functions of microbial communities from
unaffected coastal sites, (2) lack of knowledge on the sensitivity of
reference communities (e.g. bacteria, phyto-and zooplankton) to
local environmental forcing (nutrient inputs, organic and mineral
pollution, etc).
As part of the international program “Eparses 2011e2013”, a
survey was carried out from April 5 to 23, 2011 by several scientific
teams aboard the R/V Marion Dufresne II, the TAAF supply vessel, to
collect data on many aspects of terrestrial and marine biodiversity
in the Iles Eparses. This study focused on plankton microorganisms,
based on a single sample for each lagoon and ocean stations in each
of the five islands (16 stations in all, see Table 1), as well as from a
station in Mayotte lagoon, which suffers from anthropogenic impacts
as the result of a population explosion (Gourbesville and
Thomassin, 2000).
A number of important ecological questionswere covered by this
preliminary study: (i) Are there large variations in environmental