Endemism and amphidromy in freshwater fishes of insular Melanesia: critical species groups and processes for aquatic conservation
Based on the results of extensive field surveys between 2000 -2006 and compilation of new data, this study presents the current state of knowledge on species diversity and levels of endemism within the insular freshwater fish faunas of Solomon Islands, Fiji, Vanuatu and New Caledonia. Current levels of inventory, faunal uniqueness and endemism density (endemics per unit land area) are discussed. Gobiioid fishes exhibiting amphidromous life cycles (particularly within the sub-family Sicydiinae) are shown to be the major contributors to overall diversity of fish communities in insular systems of the region, including the highest proportion of island or archipelagic group endemics. These species are also shown to be significantly threatened due to key aspects of the specialized lifecycle that result in sensitivity to hydrological regime change and a widespread cultural phenomenon of harvesting the fish larvae en masse during critical migration periods. Clear trends of declining proportions of amphidromous fishes and local extirpation of endemic species in relation to deforestation are shown from the Fijian archipelago. It is suggested that by establishing landscape-seascape corridors or mosaics of managed areas containing nearshore marine, estuary and buffered river habitats, that critical elements of this dominant life cycle strategy can be managed to protect and restore endangered fish populations and the overall ecological integrity of the watershed and near shore marine areas.