TROPHIC NETWORKS OF THE SOFT-BOTTOM FISH COMMUNITY IN THE LAGOON OF NEW-CALEDONIA

Trophic networks of the New Caledonian soft bottom fish communities are studied in a wide lagoon (the North Lagoon) and a coastal bay (St Vincent Bay). The greater part of the energy used by these fishes comes from the upper levels of the food web. The benthic carnivorous fishes dominate the communities, forming more than 75 % of the overall biomass. Two other energy sources, zooplankton and detritus linked to the alluvial deposits and mangroves in the coastal bays, are important for the soft bottom fishes in coastal areas but are of only limited use for the rest of the lagoon. The main energy path is the same in the North Lagoon and St Vincent Bay: benthos-->benthic macro-carnivores-->piscivores. Two secondary paths are also important The first path, benthos-->benthic micro-carnivores--> piscivores, is important both in the North Lagoon and St Vincent Bay, The second path, zooplankton-->zooplanktivores--> piscivores, is important in St Vincent Bay only. The photosynthetic and organic detrital matter is directly assimilated through three minor paths. The path benthic algae--> herbivores-->piscivores in the North Lagoon, and the paths phytoplankton-->phytoplanktivores-->piscivores and detritus-->detritus feeders-->piscivores in St Vincent Bay.