Amphidromy and marine larval phase of ancestral Gobioids Rhyacichthys guilberti and Protogobius attiti (Teleostei: Rhyacichthyidae).

Even if amphidromous fish species contribute most to the diversity of fish communities in the tropical insular
rivers, their biological cycle remain poorly known. For the first time, the otolith elemental composition and microstructure
of two ancestral gobioids, Rhyacichthys guilberti and Protogobius attiti, were investigated to describe their biological
cycle and pelagic larval duration (PLD). The otolith analysis using a femtosecond laser ablation coupled to an inductively
coupled plasma–mass spectrometer (fs-LA-ICP-MS) revealed an amphidromous life history for R. guilberti and it
suggested a progressive habitat shift from a marine habitat to a freshwater environment for P. attiti. For the first time, an
endemic species, P. attiti, showed longer and more variable PLD (55.213.5 days) than did a widespread one
(R. guilberti: ,30 days). These results need to be confirmed by analysing more samples but suggest that factors other
than the PLD control endemism and dispersal processes. In association with this first description of the biological cycle for
both species, such an approach is a prerequisite for the management and conservation of both patrimonial species.