Abstract: In this paper we present the sex and age-at-death structure of the Aquihuecó archaeological burial site and discuss its implications for the population dynamics of northwestern Argentinian Patagonia at the beginning of the Late Holocene. The site is located on a sand-dune in the Curi Leuvú River valley (Neuquén Province) and has been defined as a burial site with a chronology that spans from 4304 ± 59 to 3650 ± 70 years BP. A minimum number of 64 individuals was estimated, including fragmentary bone remains spread on surface, and a mortality curve was built based on 43 skeletons in situ. Both sexes and all age categories, except the range 15-19.9 years, are represented in the sample. The mortality curve is characterized by a bimodal pattern with two peaks corresponding to the ranges 0-4.9 years (20.92%) and 25-29.9 (11.63%). The Juvenile/Adult Ratio and the Mean Childhood Mortality were calculated in order to characterize the population dynamics. Although both indices indicate a biased sample, other evidences (i.e. molecular, radiocarbon, isotopic and zooarchaeological) suggest it is growing population. The mortality curve was compared with those obtained for sites located in neighboring areas. The pattern is similar, but no statistically significant correlations were found.

Resumen: En este trabajo se presenta la estructura sexo-etaria del sitio Aquihuecó y se discuten sus implicancias para la dinámica poblacional del noroeste de Patagonia argentina a comienzos del Holoceno Tardío. El sitio se encuentra emplazado en un médano sobre el Río Curí Leuvú (Prov. del Neuquén) y ha sido definido como un sitio de entierro con una cronología que abarca desde 4304±59 hasta 3650±70 años AP. Se estimó un número mínimo de individuos de 64, incluyendo elementos desarticulados y fragmentarios de superficie y se confeccionó una curva de edades de muerte en base a los 43 esqueletos hallados in situ. Los resultados indican la representación de ambos sexos y todas las categorías de edad, excepto el rango 15-19,9 años. La curva está caracterizada por un patrón bimodal con dos picos correspondientes a los rangos 0-4,9 años (20,92%) y 25-29,9 (11,63%). Se calculó la proporción juveniles/adultos y la mortalidad promedio en la niñez con el fin de caracterizar la dinámica poblacional. Ambos índices señalan que se trata de una muestra sesgada aunque en base a otras líneas (i.e. molecular, radiocarbónica, isotópica y zooarqueológica) se sugiere que podría corresponder a una población creciente. La curva se comparó con otras obtenidas para sitios de áreas vecinas. Si bien el patrón general es similar, no se encontraron correlaciones estadísticamente significativas.

Limnoperna fortunei (Dunker, 1857), during its invasion process in South America, has caused severe impacts both on natural environments altering native biodiversity, ecosystem structure and function-, and on man-made structures causing economic looses. Twenty-one samples were taken from the right bank of the Uruguay River, from tributaries of the Uruguay and Paraná Rivers, the drainage of the Esteros del Ibera Wetland. Based on this fieldwork, the presence of larvae and adults of L. fortunei was determined. Also, through the comparison of environmental characteristic with the known tolerance limits for the species, the possibility of its establishment in environments not yet invaded was determined. Most of the sampling stations have features that allow the development of stable populations L. fortunei, including the rivers that drain the Esteros del Ibera, allowing access of this invasive species to this important wetland.