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

Abstract

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 (55.2 ± 13.5 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.