Sponges of the New Caledonian lagoon - IRD

18
Sponges
of the New
Caledonian
Lagoon
advent of scuba diving and underwater photography this new world finally became
more accessible, and our knowledge of these shallow seas has since increased
dramatically.
Today there is a vast library of specialised publications concerning the biology,
physics and chemistry of the sea, but unfortunately many of these documents are
unintelligible or at best difficult to comprehend for the non-specialist audience.
There are also many popular, more general books on coral reefs, but these are
often too simple, too general, and usually only display the more obvious or spectacular
reef species, concentrating in particular on mobile animals. Reef fishes were the
first to attract public interest, with their beautiful colours, shapes and behaviours,
and there are now many popular books on these animals. Corals, the reef builders,
were considered only as background scenery to these mobile animals, and most of
this "scenery" remained relatively poorly known to all but specialists. Visitors to
aquariums rarely stop to contemplate a fish-free pool, even if this pool contained a
rich assemblage of corals and other sedentary fauna - it is probable that we are
first attracted by motion and not immediately by beautiful colours or curiosity as to
"what are those"?
Gradually, divers became more interested in the "scenery", and started studying the
sedentary fauna which they had at first ignored. Subsequent developments in
underwater macrophotography and more structured collection protocols eventually
produced a superb documentation of many species within these faunas. We are
slowly but surely discovering further aspects of their biology, their preferred places
to live, their roles and interactions within ecological systems, and other characteristics
not preViously possible before the advent of scuba. Without doubt, for this "scenery"
of corals and other shallow water sedentary fauna, the use of scuba has
contributed more than any other technique to our scientific knowledge.
But the submarine world is not only a showcase! AS in the aerial world it contains a
number of distinct ecosystems. In these ecosystems, such as coral reefs, the liVing
animals, plants and microbial organisms interact with each other. These interactions
are varied and complex. Coral reefs are large ecological systems but we now
recognise that they are composed of innumerable smaller, distinct parts or subsystems,
each with their own particular faunas (e.g. soft bottom habitats on the lagoon
floor, deep canals or spur-and-grooves on outer reefs with their many small caves).
Nevertheless, each discrete part contributes to the entire reef system. Similarly,
relationships between coral reefs and other external systems are also of major
interest, particularly areas that are now subject to increasing human impact and