PRELIMINARY RECORDS OF ABUNDANCE AND MORPHOMETRY OF THE TIGER CRAB, AEGLA CONCEPCIONENSIS (SCHMITT, 1942) (ANOMURA, AEGLIDAE) IN A LAKE OF SOUTHERN CHILE

The tiger crab, Aegla concepcionensis, is a threatened endemic freshwater decapod of Chile, distributed throughout small areas of the Mediterranean region of Central Chile (37 degrees 30 similar to -38 degrees 00 similar to S). Its habitat includes streams and lakes with riparian areas dominated by native plants, with little or null human intervention. To our knowledge, the tiger crab's distribution is limited and human stressors (e.g., water withdrawal, exotic tree plantations and climate change) have led to degradation of its habitat. Based on the presence of these stressors and the virtual lack of knowledge of its ecology, the tiger crab has been categorized as Endangered (EN). This study presents a preliminary description of the species' ecology based on its abundance and its morphometrics, as well as on its feeding habits in Caburgua lake, South Central Chile. We established 16 sampling points, half of which in the shallow bathymetric stratum (0-10 m depth) of the lake itself, and half in the Lumaco stream, one of the lake's tributaries. We used baited traps to capture specimens. A. concepcionensis appeared to be found in the lake's shallow bathymetric stratum, but not in the stream. Individuals showed negative allometric growth, males were larger than females, and they showed scavenger feeding behaviour. Our findings provide useful information to help with tiger crab conservation, although more extensive surveys will be required to collect sufficient data for establishing a robust conservation program for the species in the study area.