Tras los pasos de Frenguelli en los Esteros del Iberá: el rol de las nuevas tecnologías en la revalorización de las colecciones biológicas históricas

In 1923 Joaquin Frenguelli took part in an expedition to the Ibera Region (NE Argentina) organized within the context of a major national program known as the Mollard Project. The details of this trip were documented in several publications that provided precise technical and landscape descriptions of the localities visited, particularly those where samples were collected. A joint collaboration between the Museo de La Plata and the University of Colorado (USA), aimed at studying the freshwater diatom flora of Argentina, led to undertaking a new field trip to the region in May 2019, almost 100 years after Frenguelli's expedition, offering the unique experience of going over his itinerary. The main purpose of this work was to locate the original sites visited by Frenguelli using modern technologies, such as satellite images and geographic information systems, in order to collect new materials to serve as references to evaluate the changes occurred during the 97 years elapsed between the two expeditions. To accomplish this, a schematic map published in 1924 was digitized based on the descriptions in bibliographical sources, the locations visited by Frenguelli were georeferenced by approximation, adjusting their location to the actual terrain by interpreting the author’s descriptions of those places. In addition, new samples were collected at the same sites and their geographic coordinates were recorded using GPS. Finally, satellite images captured close to the date of the field trip were obtained and processed, in order to analyze current land use and vegetation coverage throughout the study area. The comparative analysis of all these materials allowed us to establish that although large areas are still preserved in quite pristine conditions, other areas of the region have undergone marked changes associated with the expansion of urban areas, the development of roads and routes, and especially, significant changes in land use related mostly to forestry. These results represent baseline information, currently very scarce, that will enable the development of future environmental studies in the region.