Unravelling the life history of Amazonian fishes through otolith microchemistry

Amazonian fishes employ diverse migratory strategies, but the details of these behaviours remain poorly studied despite numerous environmental threats and heavy commercial exploitation of many species. Otolith microchemistry offers a practical, cost-effective means of studying fish life history in such a system. This study employed a multi-method, multi-elemental approach to elucidate the migrations of five Amazonian fishes: two ‘sedentary’ species (Arapaima sp. and Plagioscion squamosissimus), one ‘floodplain migrant’ (Prochilodus nigricans) and two long-distance migratory catfishes (Brachyplatystoma rousseauxii and B. filamentosum). The Sr : Ca and Zn : Ca patterns in Arapaima were consistent with its previously observed sedentary life history, whereas Sr : Ca and Mn : Ca indicated that Plagioscion may migrate among multiple, chemically distinct environments during different life-history stages. Mn : Ca was found to be potentially useful as a marker for identifying Prochilodus's trans...