Travelling in Microphis (Teleostei: Syngnathidae) otoliths with 2D XRF maps: twists and turns on the road of strontium incorporation - Data collection/Paris

Indo-Pacific tropical island streams are home to freshwater fish, including pipefish species (Microphis spp.). A diadromous life cycle comprising a marine transition phase would be expected, being a compelling response to cope with hostile features of labile and fragmented habitat for species sustainability. Otoliths, as reliable keepers were used to uncover life history traits in four pipefish at stake species, one of which is endemic to New Caledonia. All meet the same methodological challenge with small, fragile and mute otoliths for any landmarks using basic ob-servation tools. Synchrotron based X-ray fluorescence is an effective method to unravel fine reso-lution two-dimensional mapping of strontium distribution in the otolith. Strontium, calcium sub-stituent driven by salinity conditions, is useful to study diadromous migrations. By studying four species we uncovered plasticity in their life cycle: all individuals were amphidromous, apart from some freshwater residents. Delving deeper into the strontium pattern throughout 2D fine scale otolith images outlined unexpected strontium distribution granularity. In addition to the trivial environmental ionic conditions driving incorporation, an unusual mosaic arrangement of Sr dis-tribution is depicted that we hypothesized the trade-off expression between biological control and chemical driving forces in the otolith strontium incorporation. Related publication : Clara Lord, Vincent Haÿ, Kadda Medjoubi, Sophie Berland and Philippe Keith, in press - Travelling in Microphis (Teleostei: Syngnathidae) otoliths with 2D XRF maps: twists and turns on the road of strontium incorporation, Biology, 13.