Estuaries and saltmarshes play a fundamental role in the life cycle of many crab species. Diverse studies show that temperature and salinity modulate abundance, size frequency distribution (SFD), sex ratio and growth in crustaceans. These population parameters are usually challenging to estimate due to the high environmental variability of estuaries. Monthly samples of the estuarine crab Hemigrapsus crenulatus were taken from October 2003 to October 2004 (except July 2004) in the Tubul estuary, central Chile. We quantified temporal changes in abundance, size distribution, sex ratio and monthly growth through the annual cycle. A total of 1025 individuals were collected. Sizes ranged from 7.72–33.51 mm carapace length (CL) with a growth rate ranging between 2.13–30.5% mm CL mo−1. Size and growth rates were greater in spring-summer, suggesting a faster growth of younger crabs correlated with increasing sea temperatures in the austral summer. Overall, sex ratio was 1.75:1 in favour of males. Modal analysis identified at least seven cohorts cohabiting throughout the annual cycle. Growth parameters for males and females were the following, respectively: L∞ = 33.6 and 29.6, k = 0.69 and 0.91, t0 = –0.39 and −0.28. Changes in size distribution suggested a recruitment period during autumn and winter seasons when there are lower salinities and temperature fluctuations stresses. Generalized linear models indicated that sea temperature, salinity and chlorophyll were the environmental variables that better predicted the annual patterns in the population structure.

El análisis del patrón de asentamiento en sociedades no jerárquicas tiene un gran potencial para abordar su variabilidad, en la medida que sus niveles de integración tienen una expresión física en los espacios corresidenciales y en la distancia entre ellos. A partir de una prospección intensiva en la microrregión de Angostura, Chile central, se compara la organización espacial de los asentamientos habitacionales de los periodos alfareros del área. Se trabajó con el tamaño y densidad de los 19 sitios detectados en el área, así como su distribución espacial. Se los delimitó por medio de redes de pozos de sondeo, a partir de cuya densidad se estimó la extensión y estructura de los sitios. La asignación cronocultural se realizó a partir de la clasificación del material alfarero y por 150 fechados por termoluminiscencia. La comparación indica que los periodos Alfarero temprano e Intermedio tardío presentan tanto similitudes como diferencias. En ambos momentos el patrón de asentamiento es disperso y la principal diferencia radica en la estructura interna de los sitios. Los asentamientos del Intermedio tardío tienen una menor cantidad de concentraciones y la densidad tiende a ser mayor, lo que sugiere que la composición de las unidades residenciales es distinta, estando compuestas por un mayor número de personas en el momento más tardío.

We report multiproxy analyses of a sediment core obtained from Laguna Aculeo that spans the past 7500 years. Laguna Aculeo (33°50′S, 70°55′W) is one of the few natural inland lakes located in the Mediterranean zone of Central Chile, near the northern margin of the influence of the southern westerlies. The record shows elevated pollen counts of halophytes and seasonally drying of the lake basin prior to 5700 cal yr B.P., indicating severe aridity and warmer-than-present conditions. This was followed by the establishment of a fresh-water lake, along with an increase in arboreal and herbaceous plant diversity between 5700 and 3200 cal yr B.P. An intensification of this trend started at 3200 cal yr B.P., along with the abrupt decrease of halophytes until 100 cal yr B.P. Within this humid period, pollen accumulation rates show large-amplitude fluctuations, coeval with numerous turbidite layers, suggesting a highly variable and torrential rainfall pattern. This intense and variable precipitation regime is probably associated with the El Niño–Southern Oscillation (ENSO) phenomenon. We suggest that the modern Mediterranean climate of Central Chile was established at ∼3200 cal yr B.P. Paleovegetation and paleolimnological changes starting at 100 cal yr B.P. correlate with documented human activity surrounding the lake.