Fluid-preserved zoological specimens in Portuguese Natural History collections: a historical overview and implications to collection management and research

Fluid preservation has been one of the most common methods to preserve zoological specimens since the late 17 th century. During the last centuries, different formulae, methods and techniques have been used to preserve specimens in fluid and several “naturalist” instructions have been published by museums and other natural history related institutions to help collectors, collections managers and curators achieve the best results. However, these different methods may influence the scientific use of the specimens and impact on their long-term conservation and management. Here, we present a first review of the fluid preservation techniques used in Portuguese natural history institutions since the 18 th century. We retrieved data of 36 different publications, dating from 1779 to 1972. Details on the methods of fluid fixation and preservation, as well as the type of fluids used to euthanise, fix and preserve specimens are presented for each of the different publications. These instructions encompass the major epochs in Portuguese natural history and its most important natural history museums. We also identified specimens that were prepared under these different instructions that are still extant in Portuguese collections. Finally, we present an overview of the main challenges affecting the main Portuguese natural history museums and their fluid-preserved specimens.